OCR GCSE Triple Science
Chemistry
Recall & Retrieval Questions
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Paper 1
C1: Particles
C1.1a Describe the main features of the particle model in terms of states of matter and change of state
What are the three states of matter?
How are particles arranged in a solid?
How are particles arranged in a liquid?
How are particles arranged in a gas?
What happens to particles during melting?
What happens to particles during boiling?
C1.1b Explain in terms of the particle model the distinction between physical changes and chemical changes
What is a physical change?
What is a chemical change?
Why is melting a physical change?
Why is burning magnesium a chemical change?
What happens to particles during a physical change?
What happens to particles during a chemical change?
C1.1c Explain the limitations of the particle model in relation to changes of state when particles are represented by inelastic spheres (e.g. like bowling balls)
What does the simple particle model represent particles as?
Which force between particles is not shown by the simple particle model?
Why does the simple particle model not fully explain changes of state?
What limitation does the simple particle model have when representing the size of particles?
What limitation does the simple particle model have when representing the space between particles?
State three limitations of the simple particle model.
C1.2a Describe how and why the atomic model has changed over time
Who proposed the first modern atomic model?
What did J. J. Thomson discover?
What did Rutherford conclude from the alpha particle scattering experiment?
How did Bohr improve the atomic model?
What evidence from the Geiger and Marsden experiment supported Rutherford's model?
Why has the atomic model changed over time?
C1.2b Describe the atom as a positively charged nucleus surrounded by negatively charged electrons, with the nuclear radius much smaller than that of the atom and with most of the mass in the nucleus
What is found in the centre of an atom?
What is the charge of the nucleus?
What is the charge of an electron?
Where are electrons found in an atom?
Where is most of the mass of an atom found?
How does the size of the nucleus compare with the size of the atom?
C1.2c Recall the typical size (order of magnitude) of atoms and small molecules
What is the typical radius of an atom?
What is the typical length of a chemical bond?
What is meant by an order of magnitude?
Approximately how many nanometres are in a metre?
Why are atoms not visible with the naked eye?
Why is the typical size of atoms useful when comparing them with everyday objects?
C1.2d Recall relative charges and approximate relative masses of protons, neutrons and electrons
What is the relative charge of a proton?
What is the relative charge of a neutron?
What is the relative charge of an electron?
What is the approximate relative mass of a proton?
What is the approximate relative mass of a neutron?
What is the approximate relative mass of an electron?
C1.2e Calculate numbers of protons, neutrons and electrons in atoms and ions, given atomic number and mass number of isotopes
What is the atomic number of an atom?
What is the mass number of an atom?
How can you calculate the number of neutrons in an atom?
How can you calculate the number of electrons in a positive ion?
What is an isotope?
An atom has atomic number 17 and mass number 37. How many protons, neutrons and electrons does it contain?
C2: Elements, Compounds and Mixtures
C2.1a Explain what is meant by the purity of a substance, distinguishing between the scientific and everyday use of the term 'pure'
What is a pure substance in chemistry?
How is the everyday meaning of the word 'pure' different from the scientific meaning?
Why is pure orange juice not considered a pure substance in chemistry?
Why is distilled water considered a pure substance?
Why are mixtures not considered pure substances?
How can the scientific definition of purity be used to classify a substance?
C2.1b Use melting point data to distinguish pure from impure substances
What happens to the melting point of a pure substance?
What happens to the melting point of an impure substance?
Why do impurities affect the melting point of a substance?
How can melting point data be used to identify a pure substance?
Which would have the sharper melting point: a pure substance or an impure substance?
A substance melts over the range 76–82 °C. Is it likely to be pure or impure?
C2.1c Calculate relative formula masses of species separately and in a balanced chemical equation
What is meant by relative atomic mass (Ar)?
What is meant by relative molecular mass (Mr)?
What is meant by relative formula mass?
How is the relative formula mass of a substance calculated?
Calculate the relative formula mass (Mr) of carbon dioxide (CO₂).
Calculate the total relative formula mass of the reactants in the equation 2H₂ + O₂ → 2H₂O.
C2.1d Deduce the empirical formula of a compound from the relative numbers of atoms present or from a model or diagram and vice versa
What is an empirical formula?
How is an empirical formula different from a molecular formula?
What is the empirical formula of H₂O₂?
What is the empirical formula of C₆H₁₂O₆?
A compound contains carbon and hydrogen in the ratio 1:2. What is its empirical formula?
A compound has the empirical formula CH₂. Give one possible molecular formula.
C2.1e Explain that many useful materials are formulations of mixtures
What is meant by a formulation?
Why are formulations made from mixtures rather than pure substances?
What is an alloy?
Why are alloys considered formulations?
Give one example of a formulation used in everyday life.
Why is stainless steel described as a formulation rather than a pure substance?
C2.1f Describe, explain and exemplify the processes of filtration, crystallisation, simple distillation and fractional distillation
Which separation technique is used to separate an insoluble solid from a liquid?
Which separation technique is used to obtain crystals from a solution?
Which separation technique is used to separate a solvent from a solution?
Which separation technique is used to separate a mixture of liquids with different boiling points?
Why does simple distillation work?
Why does fractional distillation separate liquids more effectively than simple distillation?
C2.1g Describe the techniques of paper and thin layer chromatography
What is paper chromatography used to separate?
What is thin layer chromatography (TLC)?
What is an aqueous solvent?
What is a non-aqueous solvent?
What is a locating agent used for in chromatography?
Why might a non-aqueous solvent be chosen instead of water for chromatography?
C2.1h Recall that chromatography involves a stationary and a mobile phase and that separation depends on the distribution between the phases
What is the stationary phase in paper chromatography?
What is the mobile phase in paper chromatography?
Which phase moves during chromatography?
Which phase remains fixed during chromatography?
Why do different substances travel different distances during chromatography?
Explain how the distribution between the mobile and stationary phases separates a mixture.
C2.1i Interpret chromatograms, including measuring Rf values
What does Rf stand for?
How do you measure the distance travelled by a substance on a chromatogram?
How do you measure the distance travelled by the solvent front?
Write the equation used to calculate an Rf value.
Calculate the Rf value if a spot travels 4.0 cm and the solvent front travels 8.0 cm.
Why should Rf values only be compared when the same solvent and experimental conditions are used?
C2.1j Suggest suitable purification techniques given information about the substances involved
Which purification technique would you use to separate an insoluble solid from a liquid?
Which purification technique would you use to obtain a pure dissolved solid from a solution?
Which purification technique would you use to obtain a pure solvent from a solution?
Which purification technique would you use to separate two liquids with different boiling points?
Which purification technique would you use to separate the components of a coloured mixture?
How would you choose the most suitable purification technique for a mixture?
C2.1k Suggest chromatographic methods for distinguishing pure from impure substances
Which three types of chromatography are named in the specification?
How many spots would a pure substance produce on a chromatogram?
How many spots would an impure substance produce on a chromatogram?
Which type of chromatography is commonly used to separate gases?
Which type of chromatography is commonly used in school laboratories to separate coloured substances?
How can chromatography be used to distinguish a pure substance from an impure substance?
C2.2a Describe metals and non-metals and explain the differences between them on the basis of their characteristic physical and chemical properties
What is a metal?
What is a non-metal?
State two physical properties of metals.
State two physical properties of non-metals.
What type of ions do metals usually form?
What is formed when a metal reacts with oxygen?
C2.2b Explain how the atomic structure of metals and non-metals relates to their position in the Periodic Table
Where are metals found in the Periodic Table?
Where are non-metals found in the Periodic Table?
Why do metal atoms tend to lose electrons?
Why do non-metal atoms tend to gain electrons?
How does the number of outer-shell electrons differ between metals and non-metals?
How does an element's position in the Periodic Table help you identify whether it is a metal or a non-metal?
C2.2c Explain how the position of an element in the Periodic Table is related to the arrangement of electrons in its atoms and hence to its atomic number
What does the atomic number of an element represent?
What does the group number tell you about an atom?
What does the period number tell you about an atom?
How many occupied electron shells does a Period 3 element have?
How many electrons are in the outer shell of a Group 2 element?
An element has atomic number 17. State its electron arrangement, group number and period number.
C2.2d Describe and compare the nature and arrangement of chemical bonds in: ionic compounds, simple molecules, giant covalent structures, polymers and metals
What type of bonding is found in ionic compounds?
What type of bonding is found in simple molecules?
What type of bonding is found in giant covalent structures?
What type of bonding is found in polymers?
What type of bonding is found in metals?
How does the arrangement of particles in a giant covalent structure differ from that in a simple molecular substance?
C2.2e Explain chemical bonding in terms of electrostatic forces and the transfer or sharing of electrons
What happens to electrons during ionic bonding?
What happens to electrons during covalent bonding?
What is meant by electrostatic attraction?
What causes the attraction between oppositely charged ions in an ionic compound?
What causes the attraction between the nuclei and the shared pair of electrons in a covalent bond?
Explain how electron transfer leads to ionic bonding.
C2.2f Construct dot and cross diagrams for simple covalent and binary ionic substances
What does a dot and cross diagram show?
Draw a dot and cross diagram for hydrogen (H₂).
Draw a dot and cross diagram for chlorine (Cl₂).
Draw a dot and cross diagram for water (H₂O).
Draw a dot and cross diagram for sodium chloride (NaCl).
Draw a dot and cross diagram for magnesium oxide (MgO).
C2.2g Describe the limitations of particular representations and models (dot and cross diagrams, ball and stick models and two- and three-dimensional representations)
What does a dot and cross diagram show?
Give one limitation of a dot and cross diagram.
What does a ball and stick model show?
Give one limitation of a ball and stick model.
Why are two-dimensional diagrams limited when representing molecules?
Why are models useful even though they have limitations?
C2.2h Explain how the reactions of elements are related to the arrangement of electrons in their atoms and hence to their atomic number
What determines the chemical properties of an element?
Why do elements in the same group have similar chemical properties?
Why are Group 1 metals very reactive?
Why are Group 7 elements reactive?
Why are Group 0 elements unreactive?
Explain how an element's atomic number is linked to its chemical reactions.
C2.2i Explain in terms of atomic number how Mendeleev's arrangement was refined into the modern Periodic Table
Who developed the first widely accepted Periodic Table?
How did Mendeleev arrange the elements?
What discovery allowed the Periodic Table to be refined?
How are elements arranged in the modern Periodic Table?
Why did Mendeleev leave gaps in his Periodic Table?
Explain how atomic number improved the arrangement of the modern Periodic Table.
C2.3a Recall that carbon can form four covalent bonds
How many covalent bonds can a carbon atom form?
Why is carbon able to form four covalent bonds?
What type of bond does carbon form with other non-metal atoms?
Draw a carbon atom showing how it can form four covalent bonds.
Why does carbon's ability to form four covalent bonds allow many different compounds to exist?
Give one example of a substance containing carbon atoms joined by covalent bonds.
C2.3b Explain that the vast array of natural and synthetic organic compounds occur due to the ability of carbon to form families of similar compounds, chains and rings
What is an organic compound?
Why can carbon form such a large number of different compounds?
What is meant by a family of similar compounds?
What is the difference between a carbon chain and a carbon ring?
Why can both natural and synthetic organic compounds exist in such large numbers?
Explain why carbon's bonding leads to a vast range of organic compounds.
C2.3c Explain the properties of diamond, graphite, fullerenes and graphene in terms of their structures and bonding
What type of structure does diamond have?
Why is diamond extremely hard?
Why can graphite conduct electricity?
What are fullerenes?
What is graphene?
Explain how the structures and bonding of diamond and graphite result in their different properties.
C2.3d Use ideas about energy transfers and the relative strength of chemical bonds and intermolecular forces to explain the different temperatures at which changes of state occur
What happens to energy when a substance melts or boils?
What happens to energy when a substance freezes or condenses?
What are intermolecular forces?
Why do substances with stronger intermolecular forces have higher melting and boiling points?
Why is less energy needed to melt a simple molecular substance than a giant covalent substance?
Explain why different substances change state at different temperatures.
C2.3e Use data to predict states of substances under given conditions
What information is needed to predict the state of a substance?
If the temperature is below the melting point, what state will a substance be in?
If the temperature is between the melting point and boiling point, what state will a substance be in?
If the temperature is above the boiling point, what state will a substance be in?
Use melting point and boiling point data to predict the state of a substance at a given temperature.
Explain how changes in temperature can cause a substance to change state.
C2.3f Explain how the bulk properties of materials (ionic compounds; simple molecules; giant covalent structures; polymers and metals) are related to the different types of bonds they contain, their bond strengths in relation to intermolecular forces and the ways in which their bonds are arranged
Why do ionic compounds generally have high melting and boiling points?
Why do simple molecular substances usually have low melting and boiling points?
Why do giant covalent structures have very high melting and boiling points?
Why do metals conduct electricity?
How does the bonding in polymers differ from that in simple molecular substances?
Explain how bonding, bond strength and structure determine the bulk properties of ionic compounds, simple molecules, giant covalent structures, polymers and metals.
C2.3g Compare 'nano' dimensions to typical dimensions of atoms and molecules
What does the prefix "nano" mean?
What is the approximate size of a nanoparticle?
How does the size of a nanoparticle compare with the size of an atom?
How does the size of a nanoparticle compare with the size of a molecule?
Why are nanoparticles described as being on the nanometre scale?
Compare the typical dimensions of nanoparticles, atoms and molecules.
C2.3h Describe the surface area to volume relationship for different-sized particles and describe how this affects properties
What happens to the surface area to volume ratio as particle size decreases?
Which has the larger surface area to volume ratio: a large particle or a small particle?
Why do smaller particles react more quickly than larger particles?
How does increasing surface area to volume ratio affect the rate at which a substance dissolves?
Why are powders often more reactive than large lumps of the same substance?
Explain how the surface area to volume ratio affects the properties of small particles.
C2.3i Describe how the properties of nanoparticulate materials are related to their uses
What is a nanoparticle?
Why do nanoparticles often have different properties from larger particles of the same substance?
Why are nanoparticles useful as catalysts?
Why are nanoparticles used in products such as sunscreens?
Give one other use of nanoparticulate materials.
Explain how the properties of nanoparticles make them suitable for their uses.
C2.3j Explain the possible risks associated with some nanoparticulate materials
Why are scientists investigating the safety of nanoparticles?
Why can nanoparticles enter the body more easily than larger particles?
Why are the long-term effects of some nanoparticles uncertain?
Give one possible risk associated with the use of nanoparticles.
Why should the benefits of nanoparticles be weighed against their risks?
Explain why more research is needed into the use of some nanoparticulate materials.
C3: Chemical Reactions
C3.1a Use chemical symbols to write the formulae of elements and simple covalent and ionic compounds
What is a chemical formula?
Write the chemical formula for water.
Write the chemical formula for magnesium oxide.
Write the chemical formula for calcium chloride.
A compound is made from calcium ions (Ca²⁺) and nitrate ions (NO₃⁻). What is its chemical formula?
A student writes the formula for aluminium oxide as AlO. Explain why this is incorrect and write the correct chemical formula.
C3.1b Use the names and symbols of common elements and compounds and the principle of conservation of mass to write formulae and balanced chemical equations and half equations
What does it mean for a chemical equation to be balanced?
State the law of conservation of mass.
Balance the equation: H₂ + O₂ → H₂O.
Write the balanced symbol equation for magnesium reacting with oxygen.
What is a half equation?
Write the half equation for the reduction of copper(II) ions to copper.
C3.1c Use the names and symbols of common elements from a supplied Periodic Table to write formulae and balanced chemical equations where appropriate
What is the chemical symbol for calcium?
Write the chemical formula for calcium oxide.
Write the balanced symbol equation for sodium reacting with chlorine.
Write the balanced symbol equation for calcium reacting with water.
A student writes K + Cl → KCl. Correct the equation.
Write the balanced symbol equation for aluminium reacting with oxygen.
C3.1d Use the formula of common ions to deduce the formula of a compound
What is the charge on a nitrate ion?
What is the charge on an oxide ion?
Calcium ions (Ca²⁺) and chloride ions (Cl⁻) form a compound. What is its formula?
Aluminium ions (Al³⁺) and oxide ions (O²⁻) form a compound. What is its formula?
Magnesium ions (Mg²⁺) and hydroxide ions (OH⁻) form a compound. What is its formula?
Iron(III) ions (Fe³⁺) and sulfate ions (SO₄²⁻) form a compound. What is its formula?
C3.1e Construct balanced ionic equations
What is an ionic equation?
What are spectator ions?
Write the ionic equation for the reaction between silver ions and chloride ions.
Write the ionic equation for the neutralisation of hydrochloric acid by sodium hydroxide.
Why are spectator ions omitted from ionic equations?
A student writes Na⁺ + OH⁻ + H⁺ + Cl⁻ → NaCl + H₂O as an ionic equation. Write the correct ionic equation.
C3.1f Describe the physical states of products and reactants using state symbols (s, l, g and aq)
What does the state symbol (aq) mean?
What state symbol is used for a gas?
Add the correct state symbols to: Mg + HCl → MgCl₂ + H₂.
Add the correct state symbols to: AgNO₃ + NaCl → AgCl + NaNO₃.
Why are state symbols included in chemical equations?
A student labels solid sodium chloride as NaCl(aq). Write the correct state symbol.
C3.1g Recall and use the definitions of the Avogadro constant (in standard form) and of the mole
What is the Avogadro constant in standard form?
What is one mole of a substance?
How many particles are in 2 moles of a substance?
How many moles are present in 1.204 × 10²⁴ particles?
One mole of carbon has a mass of 12 g. Calculate the mass of one carbon atom.
One mole of water has a mass of 18 g. Calculate the mass of one water molecule.
C3.1h Explain how the mass of a given substance is related to the amount of that substance in moles and vice versa
What equation links mass, moles and relative formula mass?
What is meant by the relative formula mass (Mr) of a substance?
Calculate the number of moles in 36 g of water (Mr = 18).
Calculate the mass of 0.5 mol of carbon dioxide (Mr = 44).
Calculate the number of moles in 49 g of sulfuric acid (Mr = 98).
A sample contains 3 mol of calcium carbonate (Mr = 100). Calculate its mass.
C3.1i Recall and use the law of conservation of mass
State the law of conservation of mass.
Why does the total mass remain constant during a chemical reaction?
If 24 g of magnesium reacts completely with 16 g of oxygen, what mass of magnesium oxide is produced?
Why must chemical equations be balanced?
A reaction starts with 15 g of reactants. What is the total mass of products after the reaction has finished?
A student claims atoms are destroyed during chemical reactions. Explain why this is incorrect.
C3.1j Explain any observed changes in mass in non-enclosed systems during a chemical reaction and explain them using the particle model
Why can the measured mass change during a reaction carried out in an open container?
Why does burning magnesium increase the mass of the product?
Why does heating calcium carbonate in an open container decrease the measured mass?
Explain, using the particle model, why these changes in mass occur.
Why would no overall mass change be observed if the same reactions were carried out in a sealed container?
A reaction in an open flask loses 4 g of mass. Explain why this does not break the law of conservation of mass.
C3.1k Deduce the stoichiometry of an equation from the masses of reactants and products and explain the effect of a limiting quantity of a reactant
What is meant by stoichiometry?
What is a limiting reactant?
Magnesium reacts with oxygen. 24 g of magnesium reacts completely with 16 g of oxygen. Deduce the balanced symbol equation.
In a reaction, one reactant is completely used up while another remains. Which reactant is the limiting reactant?
12 g of magnesium reacts with 12 g of oxygen. Identify the limiting reactant.
Explain how the limiting reactant affects the maximum amount of product that can be formed.
C3.1l Use a balanced equation to calculate masses of reactants or products
Why must a chemical equation be balanced before carrying out mole calculations?
What is the first step when calculating masses from a balanced equation?
Calculate the mass of magnesium oxide produced from 24 g of magnesium.
Calcium carbonate decomposes according to CaCO₃ → CaO + CO₂. Calculate the mass of carbon dioxide produced from 100 g of calcium carbonate (Mr: CaCO₃ = 100, CO₂ = 44).
Calculate the mass of oxygen required to react completely with 12 g of magnesium.
Hydrogen reacts with oxygen according to 2H₂ + O₂ → 2H₂O. Calculate the mass of water produced when 4 g of hydrogen reacts completely with excess oxygen.
C3.2a Distinguish between endothermic and exothermic reactions on the basis of the temperature change of the surroundings
What is an exothermic reaction?
What is an endothermic reaction?
During an exothermic reaction, what happens to the temperature of the surroundings?
During an endothermic reaction, what happens to the temperature of the surroundings?
A reaction causes the temperature of the surroundings to increase from 20°C to 29°C. Is the reaction exothermic or endothermic?
A reaction causes the temperature of the surroundings to fall from 22°C to 15°C. Explain whether the reaction is exothermic or endothermic using the temperature change of the surroundings.
C3.2b Draw and label a reaction profile for an exothermic and an endothermic reaction
What is a reaction profile?
What is meant by activation energy?
On a reaction profile, where are the reactants shown?
On a reaction profile, where are the products shown?
Draw and label a reaction profile for an exothermic reaction, including the reactants, products, activation energy and energy change.
Draw and label a reaction profile for an endothermic reaction, including the reactants, products, activation energy and energy change.
C3.2c Explain activation energy as the energy needed for a reaction to occur
What is activation energy?
Why must reacting particles have activation energy?
What effect does increasing temperature have on the number of particles with enough activation energy?
Why does heating a reaction usually increase its rate?
A reaction does not occur at room temperature but starts when heated. Explain why.
A catalyst is added to a reaction. Explain why the reaction can occur more easily.
C3.2d Calculate energy changes in a chemical reaction by considering bond making and bond breaking energies
Is energy absorbed or released when chemical bonds are broken?
Is energy absorbed or released when chemical bonds are formed?
State the equation used to calculate the energy change of a reaction using bond energies.
A reaction requires 480 kJ to break bonds and releases 620 kJ when new bonds form. Calculate the energy change.
A reaction requires 720 kJ to break bonds and releases 650 kJ when new bonds form. Calculate the energy change and state whether the reaction is exothermic or endothermic.
Hydrogen reacts with chlorine to form hydrogen chloride. The total energy needed to break bonds is 674 kJ and the total energy released when new bonds form is 862 kJ. Calculate the energy change and state whether the reaction is exothermic or endothermic.
C3.3a Explain reduction and oxidation in terms of loss or gain of oxygen, identifying which species are oxidised and which are reduced
What is oxidation in terms of oxygen?
What is reduction in terms of oxygen?
When magnesium reacts with oxygen to form magnesium oxide, is magnesium oxidised or reduced?
Copper(II) oxide is heated with carbon to produce copper and carbon dioxide. Is copper(II) oxide oxidised or reduced?
In the reaction 2Mg + O₂ → 2MgO, identify the species that is oxidised.
In the reaction 2CuO + C → 2Cu + CO₂, identify which species is reduced and which is oxidised.
C3.3b Explain reduction and oxidation in terms of gain or loss of electrons, identifying which species are oxidised and which are reduced (Higher Tier only)
What is oxidation in terms of electrons?
What is reduction in terms of electrons?
If an atom loses electrons, is it oxidised or reduced?
If an ion gains electrons, is it oxidised or reduced?
Magnesium forms Mg²⁺ by losing two electrons. Is magnesium oxidised or reduced?
Copper(II) ions gain two electrons to form copper atoms. Explain whether copper(II) ions are oxidised or reduced.
C3.3c Recall that acids form hydrogen ions when they dissolve in water and solutions of alkalis contain hydroxide ions
Which ion is formed when an acid dissolves in water?
Which ion is present in an alkali solution?
Which ion makes a solution acidic?
Which ion makes a solution alkaline?
Hydrochloric acid dissolves in water. Which ion is responsible for its acidity?
Sodium hydroxide dissolves in water. Explain why the solution is alkaline.
C3.3d Describe neutralisation as acid reacting with alkali or a base to form a salt plus water
What is a neutralisation reaction?
What two products are always formed when an acid reacts with an alkali?
What is formed when hydrochloric acid reacts with sodium hydroxide?
Can a base neutralise an acid?
Sulfuric acid reacts with potassium hydroxide. What two types of products are formed?
Explain why the reaction between an acid and an alkali is called neutralisation.
C3.3e Recognise that aqueous neutralisation reactions can be generalised to hydrogen ions reacting with hydroxide ions to form water
Which two ions react during neutralisation?
What is the product of H⁺ + OH⁻?
Write the ionic equation for neutralisation.
Why are spectator ions omitted from the ionic equation for neutralisation?
Hydrochloric acid reacts with sodium hydroxide. Which ions actually react?
Nitric acid reacts with potassium hydroxide. Write the ionic equation for the reaction.
C3.3f Recall that carbonates and some metals react with acids and write balanced equations predicting products from given reactants
What gas is produced when a metal reacts with an acid?
What gas is produced when a carbonate reacts with an acid?
Write the balanced equation for magnesium + hydrochloric acid.
Write the balanced equation for calcium carbonate + hydrochloric acid.
Nitric acid reacts with zinc. Predict the products.
Sulfuric acid reacts with sodium carbonate. Write the balanced symbol equation.
C3.3g Use and explain the terms dilute and concentrated (amount of substance) and weak and strong (degree of ionisation) in relation to acids (Higher Tier only)
What is meant by a concentrated acid?
What is meant by a dilute acid?
What is meant by a strong acid?
What is meant by a weak acid?
Which contains more acid particles per unit volume: a concentrated acid or a dilute acid?
A solution of ethanoic acid and a solution of hydrochloric acid have the same concentration. Explain why hydrochloric acid has the lower pH.
C3.3h Recall that relative acidity and alkalinity are measured by pH
What scale is used to measure acidity and alkalinity?
What pH value is neutral?
Is a solution with pH 3 acidic or alkaline?
Is a solution with pH 11 acidic or alkaline?
Which solution is more acidic: pH 2 or pH 5?
A solution has a pH of 8. Describe its acidity or alkalinity.
C3.3i Describe neutrality and relative acidity and alkalinity in terms of the effect of the concentration of hydrogen ions on the numerical value of pH (whole numbers only)
What is the pH of a neutral solution?
What happens to pH as the concentration of hydrogen ions increases?
Which solution has the higher hydrogen ion concentration: pH 2 or pH 4?
Which solution has the lower hydrogen ion concentration: pH 11 or pH 9?
A solution changes from pH 7 to pH 3. Has the hydrogen ion concentration increased or decreased?
Explain why a solution with pH 1 is more acidic than a solution with pH 4.
C3.3j Use the idea that as hydrogen ion concentration increases by a factor of ten, the pH value of a solution decreases by one
By what factor does hydrogen ion concentration change when pH decreases by one?
A solution changes from pH 6 to pH 5. How has the hydrogen ion concentration changed?
A solution changes from pH 4 to pH 2. By what factor has the hydrogen ion concentration changed?
Which has the greater hydrogen ion concentration: pH 3 or pH 6?
A solution has a hydrogen ion concentration ten times greater than another solution. How do their pH values differ?
Solution A has pH 2 and solution B has pH 5. How many times greater is the hydrogen ion concentration in solution A?
C3.3k Describe techniques and apparatus used to measure pH
What indicator gives a full range of pH colours?
What instrument gives the most accurate measurement of pH?
What colour is universal indicator in a neutral solution?
Why is a pH meter more accurate than universal indicator?
Which method would you use to measure the pH of a colourless solution to two decimal places?
A student needs to compare the pH of several unknown solutions accurately. Explain which apparatus they should use and why.
C3.4a Recall that metals (or hydrogen) are formed at the cathode and non-metals are formed at the anode in electrolysis using inert electrodes
What is formed at the cathode during electrolysis using inert electrodes?
What is formed at the anode during electrolysis using inert electrodes?
What is a positive ion called?
What is a negative ion called?
Molten lead bromide is electrolysed using inert electrodes. Which product forms at the cathode?
Molten sodium chloride is electrolysed using inert electrodes. Which product forms at the anode?
C3.4b Predict the products of electrolysis of binary ionic compounds in the molten state
Why must a binary ionic compound be molten before it can be electrolysed?
What are the products of electrolysis of molten sodium chloride?
What are the products of electrolysis of molten lead bromide?
What are the products of electrolysis of molten magnesium oxide?
Molten potassium bromide is electrolysed. Predict the product at each electrode.
Molten aluminium oxide is electrolysed. Predict the product at the cathode and the product at the anode.
C3.4c Describe competing reactions in the electrolysis of aqueous solutions of ionic compounds in terms of the different species present
What does the term competing reactions mean in electrolysis?
Why do competing reactions occur during the electrolysis of aqueous ionic solutions?
During the electrolysis of aqueous sodium chloride using inert electrodes, which gas is produced at the cathode?
During the electrolysis of aqueous copper(II) sulfate using inert electrodes, which metal is produced at the cathode?
Aqueous sodium chloride is electrolysed using inert electrodes. Predict the product at the anode.
Explain why different products are formed during the electrolysis of molten sodium chloride and aqueous sodium chloride.
C3.4d Describe electrolysis in terms of the ions present and reactions at the electrodes
What happens to positive ions at the cathode?
What happens to negative ions at the anode?
What is a half equation?
Write the half equation for the formation of sodium during the electrolysis of molten sodium chloride.
Write the half equation for the formation of chlorine during the electrolysis of molten sodium chloride.
Copper(II) sulfate solution is electrolysed using inert electrodes. Write the half equation for the reaction at the cathode.
C3.4e Describe the technique of electrolysis using inert and non-inert electrodes
What is an inert electrode?
Give one example of an inert electrode.
What is a non-inert electrode?
Why does an inert electrode not react during electrolysis?
Why can a non-inert electrode change during electrolysis?
Copper is purified by electrolysis using copper electrodes. Explain why a non-inert electrode is used instead of an inert electrode.
Paper 2
C4: Predicting and identifying reactions and products
C4.1a Recall the simple properties of Groups 1, 7 and 0
What are the Group 1 elements called?
What are the Group 7 elements called?
Why are the Group 0 elements also known as the noble gases?
State one physical property of Group 1 metals.
A student places sodium in water. Describe what is observed.
Chlorine gas is bubbled through potassium iodide solution. Predict what happens.
C4.1b Explain how observed simple properties of Groups 1, 7 and 0 depend on the outer shell of electrons of the atoms and predict properties from given trends down the groups
How many electrons are in the outer shell of a Group 1 atom?
How many electrons are in the outer shell of a Group 7 atom?
Why do Group 1 metals become more reactive down the group?
Why do Group 7 halogens become less reactive down the group?
Which is more reactive: potassium or sodium? Explain your answer.
Predict whether bromine or chlorine is more likely to gain an electron, and explain why.
C4.1c Recall the general properties of transition metals and their compounds and exemplify these by reference to a small number of transition metals
Name one general property of transition metals.
Compared with Group 1 metals, do transition metals have a higher or lower density?
Why are many transition metal compounds coloured?
Give one use of transition metals as catalysts.
Iron is used to make bridges instead of sodium. Explain why.
Copper(II) sulfate solution is blue. What does this tell you about transition metal compounds?
C4.1d Predict possible reactions and probable reactivity of elements from their positions in the Periodic Table
What information can the position of an element in the Periodic Table provide?
Which is more reactive: a Group 1 metal or a Group 0 element?
Predict whether calcium will react more vigorously with water than magnesium.
Predict whether fluorine or iodine is more reactive.
An unknown element is below sodium in Group 1. Predict how its reactivity compares with sodium.
An unknown element is below bromine in Group 7. Predict how its reactivity compares with bromine and explain your answer.
C4.1e Explain how the reactivity of metals with water or dilute acids is related to the tendency of the metal to form its positive ion
Why do metals react?
What happens to a metal atom when it forms a positive ion?
Why are more reactive metals more likely to react with dilute acids?
Why do more reactive metals react more vigorously with water?
Magnesium reacts with dilute hydrochloric acid faster than copper. Explain why.
Potassium reacts violently with water, whereas silver does not react. Explain this difference in terms of the tendency to form positive ions.
C4.1f Deduce an order of reactivity of metals based on experimental results
What is a reactivity series?
What does it mean if one metal displaces another from its compound?
Zinc displaces copper from copper sulfate solution. Which metal is more reactive?
Copper does not displace magnesium from magnesium sulfate solution. Which metal is more reactive?
A metal reacts vigorously with dilute acid, while another reacts only slowly. Which is higher in the reactivity series?
Metal X displaces Y, Y displaces Z, and Z does not displace X. Deduce the order of reactivity of X, Y and Z.
C4.2a Describe tests to identify selected gases
Which gas relights a glowing splint?
Which gas produces a squeaky pop with a lit splint?
What observation shows that carbon dioxide is present when bubbled through limewater?
Explain why chlorine gas bleaches damp blue litmus paper.
A colourless gas relights a glowing splint. Identify the gas.
A colourless gas turns limewater milky. Identify the gas.
C4.2b Describe tests to identify aqueous cations and aqueous anions
Which reagent is used to test for aqueous metal cations?
Which reagent is used to test for chloride, bromide and iodide ions?
Which reagent is used to test for sulfate ions?
Explain why dilute acid is added before testing for sulfate ions.
A white precipitate forms when sodium hydroxide is added to a solution. The precipitate dissolves in excess sodium hydroxide. Identify the cation.
What does a cream colour precipitate with aqueous silver nitrate indicate?
C4.2c Describe how to perform a flame test
Why is hydrochloric acid used to clean the wire before a flame test?
Which part of the flame should the sample be placed in?
Why must the wire be cleaned before testing another sample?
Explain why a clean nichrome wire is used in flame tests.
Describe how to carry out a flame test on an unknown solid.
A student forgets to clean the wire between tests. Explain how this could affect the results.
C4.2d Identify species from test results
What does a white precipitate with acidified silver nitrate indicate?
What does a green precipitate with sodium hydroxide indicate?
What does a white precipitate with acidified barium chloride indicate?
Explain what a light blue precipitate with sodium hydroxide shows.
A solution gives a brown precipitate with sodium hydroxide. Identify the cation.
A solution gives a white precipitate with acidified barium chloride. Identify the anion.
C4.2e Interpret flame tests to identify metal ions
Which metal ion produces a yellow flame?
Which metal ion produces a lilac flame?
Which metal ion produces a brick-red flame?
Explain how flame tests are used to identify metal ions.
A flame test produces a crimson-red flame. Identify the metal ion.
An unknown sample produces a blue-green flame. Identify the metal ion.
C4.2f Describe the advantages of instrumental methods of analysis
Name one advantage of instrumental methods of analysis.
Which is generally more accurate: chemical tests or instrumental methods?
Why are instrumental methods more sensitive than simple chemical tests?
Explain why instrumental methods are often preferred in industry.
A sample contains a very small amount of an impurity. Explain why an instrumental method is more suitable than a simple chemical test.
A laboratory needs to analyse hundreds of samples quickly. Explain why instrumental methods are the best choice.
C4.2g Interpret an instrumental result given appropriate data in chart or tabular form, when accompanied by a reference set of data in the same form
Which instrumental technique uses a mass spectrum?
What does the highest peak on a mass spectrum usually represent?
What information can a reference mass spectrum provide?
Explain how a mass spectrum can be used to identify an unknown substance.
A mass spectrum matches the reference spectrum for methane. Identify the unknown substance.
An unknown sample produces a mass spectrum identical to a reference sample. What conclusion can be made about the identity of the sample?
C5: Monitoring and controlling chemical reactions
C5.1a Explain how the concentration of a solution in mol/dm³ is related to the mass of the solute and the volume of the solution
What is meant by the concentration of a solution?
What is the unit of concentration used in chemistry?
Explain how increasing the mass of solute affects the concentration if the volume stays the same.
Explain how increasing the volume of solution affects the concentration if the mass of solute stays the same.
A solution contains 2.0 mol of sodium chloride in 0.50 dm³ of solution. Calculate the concentration.
A solution has a concentration of 0.40 mol/dm³ and a volume of 0.25 dm³. Calculate the amount of solute in moles.
C5.1b Describe the technique of titration
What piece of apparatus is used to accurately deliver the acid during a titration?
Why is an indicator added during a titration?
Explain why the conical flask is swirled while carrying out a titration.
Explain why the burette reading should be recorded before and after the titration.
Describe the steps needed to carry out an acid–alkali titration.
A student overshoots the end point during a titration. Explain why the result should not be used.
C5.1c Explain the relationship between the volume of a solution of known concentration of a substance and the volume or concentration of another substance that react completely together
What is the purpose of a titration?
What does it mean if two substances react completely together?
Explain why the balanced equation is needed for titration calculations.
Explain why knowing the concentration of one solution allows the concentration of another to be found.
25.0 cm³ of hydrochloric acid completely neutralises 25.0 cm³ of sodium hydroxide of concentration 0.10 mol/dm³. Calculate the concentration of the hydrochloric acid.
A titration shows that 20.0 cm³ of sodium hydroxide reacts exactly with 10.0 cm³ of sulfuric acid. The sodium hydroxide concentration is known. Explain how the sulfuric acid concentration can be determined.
C5.1d Describe the relationship between molar amounts of gases and their volumes and vice versa
What volume does 1 mole of any gas occupy at room temperature and pressure?
What is the unit used for molar gas volume?
Explain why equal numbers of moles of different gases occupy the same volume at room temperature and pressure.
Explain how the number of moles of a gas can be found from its volume.
Calculate the number of moles in 48 dm³ of oxygen at room temperature and pressure.
A sample contains 0.50 mol of carbon dioxide. Calculate its volume at room temperature and pressure.
C5.1e Calculate the volumes of gases involved in reactions using the molar gas volume at room temperature and pressure (assumed to be 24 dm³)
What molar gas volume should be used in GCSE calculations?
What volume is occupied by 2 moles of gas at room temperature and pressure?
Explain why balanced equations are needed before calculating gas volumes.
Explain how mole ratios are used to calculate gas volumes.
Calcium carbonate produces 0.50 mol of carbon dioxide. Calculate the volume of gas produced at room temperature and pressure.
48 dm³ of hydrogen reacts with chlorine to form hydrogen chloride. Calculate the volume of hydrogen chloride produced.
C5.1f Explain how the mass of a solute and the volume of the solution is related to the concentration of the solution
What happens to the concentration if more solute is dissolved in the same volume?
What happens to the concentration if more water is added to a solution?
Explain why doubling the volume of a solution halves its concentration if no solute is added.
Explain why concentration depends on both the amount of solute and the volume of solution.
A solution contains 10 g of solute in 250 cm³ of solution. Another contains 10 g in 500 cm³. Which is more concentrated?
Two solutions contain the same mass of solute. Solution A has half the volume of Solution B. Compare their concentrations.
C5.1g Calculate the theoretical mass of a product from a given mass of reactant
What is meant by the theoretical yield?
Why is a balanced equation needed to calculate theoretical yield?
Explain why the amount of reactant affects the theoretical yield.
Explain why the relative formula masses must be used in theoretical yield calculations.
Calculate the theoretical mass of magnesium oxide produced from 2.4 g of magnesium.
A reaction has a theoretical yield of 16 g of product. Explain how this value is determined.
C5.1h Calculate the percentage yield of a reaction product from the actual yield of a reaction
What is meant by percentage yield?
What is meant by the actual yield?
Explain why the percentage yield is usually less than 100%.
Explain the difference between actual yield and theoretical yield.
A reaction has a theoretical yield of 20 g and an actual yield of 15 g. Calculate the percentage yield.
A reaction has a percentage yield of 80%. If the theoretical yield is 50 g, calculate the actual yield.
C5.1i Define the atom economy of a reaction
What is atom economy?
Why is a high atom economy desirable?
Explain why reactions with a low atom economy produce more waste.
Explain why atom economy is important in industry.
Which reaction is likely to be more sustainable: one with an atom economy of 95% or 45%?
Explain why manufacturers aim to use reactions with a high atom economy.
C5.1j Calculate the atom economy of a reaction to form a desired product from the balanced equation
What information is needed to calculate atom economy?
Why must the chemical equation be balanced before calculating atom economy?
Explain why relative formula masses are used in atom economy calculations.
Explain why unwanted products reduce atom economy.
Calculate the atom economy for the reaction: CaCO₃ → CaO + CO₂ (desired product: CaO).
A reaction produces one desired product and one unwanted product. Calculate the atom economy using the balanced equation.
C5.1k Explain why a particular reaction pathway is chosen to produce a specified product given appropriate data
Name one factor that may be considered when choosing a reaction pathway.
What is meant by the term reaction pathway?
Explain why a reaction with a high percentage yield may be chosen.
Explain why a reaction with a high atom economy is often preferred.
Two reaction pathways produce the same product. One has a higher atom economy but a lower rate. Suggest which may be chosen if reducing waste is the priority.
Given data for two reaction pathways including yield, atom economy, reaction rate and useful by-products, decide which pathway should be chosen and justify your answer.
C5.2a Suggest practical methods for determining the rate of a given reaction
What is meant by the rate of a chemical reaction?
Name one practical method used to measure the rate of a reaction.
Explain how measuring the volume of gas produced can determine the rate of a reaction.
Explain how measuring the loss of mass can determine the rate of a reaction.
Suggest a suitable method to measure the rate of a reaction that produces carbon dioxide gas.
A reaction forms an insoluble precipitate. Suggest the most suitable method to measure its rate.
C5.2b Interpret rate of reaction graphs
What does the gradient of a rate graph represent?
What does a horizontal section on a rate graph show?
Explain why the gradient becomes less steep as a reaction proceeds.
Explain why a reaction stops increasing in mass loss after a certain time.
A graph shows a steeper initial gradient than another graph. Which reaction has the faster initial rate?
Two reactions produce the same final volume of gas, but one graph is steeper. Compare the two reactions.
C5.2c Describe the effect of changes in temperature, concentration, pressure and surface area on rate of reaction
What happens to the rate of reaction when temperature increases?
What happens to the rate of reaction when the concentration of a solution increases?
Explain why increasing the surface area of a solid increases the rate of reaction.
Explain why increasing the pressure of a reacting gas increases the rate of reaction.
Powdered calcium carbonate reacts faster with hydrochloric acid than marble chips. Explain why.
A gas reaction is carried out at twice the original pressure. Predict the effect on the rate of reaction.
C5.2d Explain the effects on rates of reaction of changes in temperature, concentration and pressure in terms of frequency and energy of collision between particles
What is meant by a successful collision?
What is activation energy?
Explain why increasing temperature increases the frequency of successful collisions.
Explain why increasing concentration increases the rate of reaction.
Explain why increasing the pressure of reacting gases increases the rate of reaction.
A reaction is heated from 20°C to 40°C. Explain why the reaction becomes faster using collision theory.
C5.2e Explain the effects on rates of reaction of changes in the size of the pieces of a reacting solid in terms of surface area to volume ratio
What is meant by surface area to volume ratio?
Which has the larger surface area to volume ratio: a powder or a large lump?
Explain why powdered solids react faster than large pieces.
Explain how surface area affects the number of collisions.
Calcium carbonate powder reacts faster than marble chips with acid. Explain why.
A student crushes zinc granules before reacting them with hydrochloric acid. Explain the effect on the reaction rate.
C5.2f Describe the characteristics of catalysts and their effect on rates of reaction
What is a catalyst?
Is a catalyst used up during a chemical reaction?
Explain how a catalyst affects the rate of reaction.
Explain why a catalyst can be used repeatedly.
Manganese(IV) oxide is added to hydrogen peroxide. Explain its role.
A reaction is too slow for industrial use. Explain how adding a catalyst could solve this problem.
C5.2g Identify catalysts in reactions
What is the catalyst used in the decomposition of hydrogen peroxide?
How can you identify the catalyst in a chemical equation?
Explain why the catalyst is not included as a reactant or product in the overall equation.
Explain why a catalyst has the same mass before and after a reaction.
In the reaction 2H₂O₂ → 2H₂O + O₂, manganese(IV) oxide is added. Identify the catalyst.
A reaction mixture contains zinc, sulfuric acid and copper powder. Identify the catalyst.
C5.2h Explain catalytic action in terms of activation energy
What is activation energy?
What effect does a catalyst have on activation energy?
Explain why lowering the activation energy increases the reaction rate.
Explain why a catalyst does not change the overall energy change of a reaction.
Draw or describe how the reaction profile changes when a catalyst is used.
A catalyst is added to an exothermic reaction. Explain why the reaction becomes faster even though the energy released stays the same.
C5.2i Recall that enzymes act as catalysts in biological systems
What type of molecule is an enzyme?
What is the role of an enzyme in a biological reaction?
Explain why enzymes are described as biological catalysts.
Explain why enzymes are not used up during the reactions they catalyse.
Amylase speeds up the breakdown of starch. Identify the role of amylase.
Explain why a reaction in a living cell would be too slow without enzymes.
C5.3a Recall that some reactions may be reversed by altering the reaction conditions
What is a reversible reaction?
What symbol is used to represent a reversible reaction?
Explain how a reversible reaction differs from an irreversible reaction.
Explain why some reactions can proceed in both directions.
A reaction reaches equilibrium. Explain what could happen if the temperature is changed.
A reversible reaction is heated. Predict whether the reaction can continue in the reverse direction.
C5.3b Recall that dynamic equilibrium occurs in a closed system when the rates of forward and reverse reactions are equal
What is meant by dynamic equilibrium?
In what type of system can dynamic equilibrium be established?
Explain what is happening to the forward and reverse reactions at dynamic equilibrium.
Explain why the concentrations of reactants and products remain constant at equilibrium.
A reaction is at dynamic equilibrium in a sealed flask. Explain what happens to the reactants and products over time.
A student says, "The reaction has stopped because equilibrium has been reached." Explain why this statement is incorrect.
C5.3c Predict the effect of changing reaction conditions on equilibrium position and suggest appropriate conditions to produce as much of a particular product as possible
What happens to the position of equilibrium if the concentration of a reactant is increased?
What happens to the position of equilibrium if a product is removed?
Explain why increasing the concentration of a reactant shifts the equilibrium position.
Explain how changing the temperature can affect the position of equilibrium.
A reversible reaction is exothermic in the forward direction. Predict the effect of decreasing the temperature on the yield of products.
A reversible reaction produces fewer moles of gas on the product side than on the reactant side. Predict the effect of increasing the pressure and explain your answer.
C6 Global Challenges
C6.1a Explain, using the position of carbon in the reactivity series, the principles of industrial processes used to extract metals, including extraction of a non-ferrous metal
Where is carbon positioned in the reactivity series compared with iron?
Which metals can be extracted from their ores using carbon?
Explain why carbon can be used to extract iron from iron oxide.
Explain why carbon cannot be used to extract aluminium from aluminium oxide.
Copper oxide is heated with carbon. Predict the products of the reaction.
Explain why zinc can be extracted using carbon but sodium cannot.
C6.1b Explain why and how electrolysis is used to extract some metals from their ores
Which metals must be extracted using electrolysis?
Why is electrolysis needed to extract aluminium?
Explain why carbon cannot extract metals above it in the reactivity series.
Explain how electrolysis extracts aluminium from aluminium oxide.
Aluminium oxide is electrolysed. Identify the product formed at the cathode.
Explain why electrolysis is used instead of carbon to extract sodium.
C6.1c Evaluate alternative biological methods of metal extraction
What is meant by bioleaching?
What is meant by phytomining?
Explain how bacteria are used in bioleaching.
Explain how plants are used in phytomining.
Suggest one advantage of phytomining over traditional mining.
A low-grade copper ore is available. Evaluate whether bioleaching or carbon extraction is the better method.
C6.1d Explain the trade-off between rate of production of a desired product and position of equilibrium in some industrially important processes
What is meant by a trade-off in an industrial process?
Name one industrial process that involves a reversible reaction.
Explain why a higher temperature often increases the reaction rate but decreases the equilibrium yield in the Haber process.
Explain why industries do not always use the conditions that give the highest yield.
Suggest why the Haber process operates at about 450°C instead of a much lower temperature.
Explain why industrial chemists choose compromise conditions for equilibrium reactions.
C6.1e Interpret graphs of reaction conditions versus rate
What does a steeper gradient on a rate graph show?
What happens to the reaction rate when temperature increases?
Explain how a graph can be used to compare reaction rates at different temperatures.
Explain why the rate eventually becomes constant or stops increasing.
A graph shows that doubling the pressure increases the reaction rate. Describe the trend shown.
A graph compares reaction rate with temperature and equilibrium yield. Determine the best operating temperature and justify your choice.
C6.1f Explain how the commercially used conditions for an industrial process are related to the availability and cost of raw materials and energy supplies, control of equilibrium position and rate
Name one factor considered when choosing industrial reaction conditions.
Why is the cost of energy important in industrial chemistry?
Explain why industries aim to balance reaction rate with energy costs.
Explain why the availability of raw materials affects industrial processes.
A factory can increase the reaction temperature to produce products faster. Suggest one disadvantage of doing this.
An industrial process can operate under two different conditions. One gives a higher yield but uses much more energy. Explain which is likely to be chosen and why.
C6.1g Explain the importance of the Haber process in agricultural production
What is the main product of the Haber process?
What is ammonia used to manufacture?
Explain why the Haber process is important for agriculture.
Explain why nitrogen is essential for plant growth.
Explain how the use of ammonia-based fertilisers increases crop yield.
A farmer wants to increase wheat production. Explain why fertilisers made using the Haber process would help.
C6.1h Compare the industrial production of fertilisers with laboratory syntheses of the same products
What is the main aim of industrial fertiliser production?
What is the main aim of laboratory synthesis?
Explain one difference between industrial and laboratory production of fertilisers.
Explain why industrial production is carried out on a much larger scale than laboratory synthesis.
Suggest one advantage of industrial fertiliser production over laboratory synthesis.
Compare the production of ammonium nitrate in industry with its preparation in a school laboratory.
C6.1i Recall the importance of nitrogen, phosphorus and potassium compounds in agricultural production
Which element in fertilisers is needed for leafy growth?
Which element in fertilisers is needed for root growth?
Explain why potassium compounds are added to fertilisers.
Explain why NPK fertilisers improve crop production.
A farmer wants to improve root development in carrot plants. Which nutrient should be increased?
A fertiliser contains nitrogen but no potassium. Suggest one effect this may have on crop growth.
C6.1j Describe the industrial production of fertilisers as several integrated processes using a variety of raw materials
Name one fertiliser made from ammonia.
Name another fertiliser made from ammonia.
Explain why ammonia is an important raw material in fertiliser manufacture.
Explain how several industrial processes are linked together to produce fertilisers.
Explain how ammonium nitrate is produced from ammonia.
Describe how ammonia can be converted into ammonium sulfate in industry.
C6.1k Describe the basic principles in carrying out a life-cycle assessment of a material or product
What is meant by a life-cycle assessment?
Name one stage included in a life-cycle assessment.
Explain why transport is included in a life-cycle assessment.
Explain why disposal of a product is considered in a life-cycle assessment.
List the stages that should be considered when carrying out a life-cycle assessment for a plastic bottle.
Explain why a life-cycle assessment is useful when comparing two products.
C6.1l Interpret data from a life-cycle assessment of a material or product
What information does a life-cycle assessment provide?
What does a lower environmental impact indicate in a life-cycle assessment?
Explain how life-cycle assessment data can be used to compare two products.
Explain why different stages contribute differently to the total environmental impact.
A life-cycle assessment shows that transport has the greatest environmental impact. Suggest one way this impact could be reduced.
Two shopping bags have different life-cycle assessment data. Determine which is more environmentally sustainable and justify your choice.
C6.1m Describe a process where a material or product is recycled for a different use, and explain why this is viable
What is meant by recycling?
What is meant by recycling a material for a different use?
Explain why recycled materials can be used to make different products.
Explain why recycling is often economically viable.
Suggest a different use for recycled glass bottles.
Explain why recycling aluminium cans into bicycle frames may be a viable process.
C6.1n Evaluate factors that affect decisions on recycling
Name one factor that affects whether a material is recycled.
Why is the cost of recycling important?
Explain why energy requirements affect recycling decisions.
Explain why the availability of recycling facilities affects recycling rates.
A material is difficult to separate from household waste. Explain how this affects the decision to recycle it.
Evaluate whether a material should be recycled if recycling costs more than producing a new material.
C6.1o Describe the composition of some important alloys in relation to their properties and uses
What is an alloy?
Name the main metal in brass.
Explain why alloys are often harder than pure metals.
Explain why steel is used instead of pure iron for construction.
Suggest why bronze is used for statues instead of pure copper.
An aircraft requires a material that is both strong and lightweight. Explain why duralumin is a suitable choice.
C6.1p Describe the process of corrosion and the conditions which cause corrosion
What is corrosion?
Which two substances are needed for iron to rust?
Explain why iron rusts only when both oxygen and water are present.
Explain why salt water increases the rate of corrosion.
An iron nail is kept in dry air. Predict whether it will rust.
Explain why a steel bridge near the sea rusts more quickly than one inland.
C6.1q Explain how mitigation of corrosion is achieved by creating a physical barrier to oxygen and water and by sacrificial protection
Name one method of preventing corrosion by forming a physical barrier.
What is sacrificial protection?
Explain how painting prevents rusting.
Explain how galvanising protects iron from corrosion.
A scratch exposes the iron beneath a layer of paint. Explain why rust may form.
Explain why zinc continues to protect iron even if the zinc coating is scratched.
C6.1r Compare quantitatively the physical properties of glass and clay ceramics, polymers, composites and metals
Which class of materials generally has the highest electrical conductivity?
Which class of materials is generally the least dense?
Explain why composites often have better properties than their individual components.
Explain why polymers are generally poorer conductors than metals.
Compare the strength and density of a composite and a polymer.
A material is needed that is strong, lightweight and resistant to corrosion. Which class of material is most suitable?
C6.1s Explain how the properties of materials are related to their uses and select appropriate materials given details of the usage required
Which property makes copper suitable for electrical wiring?
Which property makes glass suitable for windows?
Explain why stainless steel is used for cutlery.
Explain why polymers are often used for electrical insulation.
Select the most suitable material for making a drinks bottle and justify your choice.
A bridge requires a material that is strong, durable and resistant to corrosion. Select the most suitable material and explain your choice.
C6.2a Recognise functional groups and identify members of the same homologous series
What is a functional group?
Which functional group is found in alcohols?
Explain what is meant by a homologous series.
Explain how the functional group identifies the homologous series of an organic compound.
Which homologous series does CH₃CH₂COOH belong to?
A compound contains a carbon–carbon double bond but no other functional groups. Identify its homologous series.
C6.2b Name and draw the structural formulae, using fully displayed formulae, of the first four members of the straight chain alkanes, alkenes, alcohols and carboxylic acids
What is the name of the third straight-chain alkane?
What is the name of the first carboxylic acid?
Explain how the names of the first four straight-chain alkenes are related to the number of carbon atoms they contain.
Explain how the displayed formula of an alcohol shows that it belongs to the alcohol homologous series.
Draw the fully displayed formula of but-1-ene.
Draw the fully displayed formula of propanoic acid.
C6.2c Predict the formulae and structures of products of reactions of the first four and other given members of the homologous series of alkanes, alkenes and alcohols
What are the products of the complete combustion of an alkane?
What is added across the carbon–carbon double bond during the hydrogenation of an alkene?
Explain why bromine reacts with alkenes but not alkanes.
Explain how potassium manganate(VII) converts an alcohol into a carboxylic acid.
Ethene reacts with hydrogen. Predict the product formed.
Propan-1-ol is heated with potassium manganate(VII). Predict the organic product formed.
C6.2d Recall the basic principles of addition polymerisation by reference to the functional group in the monomer and the repeating units in the polymer
Which homologous series is used as the monomer in addition polymerisation?
Which bond in the monomer opens during addition polymerisation?
Explain why addition polymerisation only occurs with unsaturated monomers.
Explain what is meant by a repeating unit in an addition polymer.
Draw the repeating unit formed from ethene.
Draw the repeating unit formed from propene.
C6.2e Explain the basic principles of condensation polymerisation
What small molecule is produced during condensation polymerisation?
Name one type of condensation polymer.
Explain why each monomer must contain at least two functional groups for condensation polymerisation.
Explain how condensation polymerisation differs from addition polymerisation.
A polyester is made from a diol and a dicarboxylic acid. Name the small molecule produced.
Explain why ethanol cannot form a condensation polymer by itself.
C6.2f Describe practical techniques to make a polymer by condensation
What type of polymer is made by condensation polymerisation?
Name the practical used in school to demonstrate condensation polymerisation.
Explain why two different monomers are used to make nylon.
Explain why a fibre forms where the two solutions meet.
During the nylon rope trick, why is the polymer pulled continuously from the boundary between the two liquids?
A student stops pulling the nylon thread during the practical. Explain why no more nylon can be collected.
C6.2g Deduce the structure of an addition polymer from a simple alkene monomer and vice versa
Which type of monomer forms an addition polymer?
What do the brackets and n represent in the displayed formula of an addition polymer?
Explain how the repeating unit of an addition polymer is related to its alkene monomer.
Explain how you can identify the monomer from the repeating unit of an addition polymer.
Deduce the monomer used to produce the repeating unit –CH₂–CH₂–.
An addition polymer has the repeating unit –CH₂–CH(CH₃)–. Deduce the monomer.
C6.2h Recall that DNA is a polymer made from four different monomers called nucleotides and that other important naturally-occurring polymers are based on sugars and amino-acids
What type of polymer is DNA?
What are the monomers that make up DNA called?
Explain how DNA differs from an addition polymer.
Explain why proteins are described as naturally occurring polymers.
Which type of monomer joins together to form proteins?
A polymer is made from amino acids. Identify the type of naturally occurring polymer formed.
C6.2i Recall that it is the generality of reactions of functional groups that determine the reactions of organic compounds
What determines the reactions of an organic compound?
Which part of an organic molecule is responsible for its characteristic reactions?
Explain why ethanol and propan-1-ol have similar chemical reactions.
Explain why ethene reacts differently from ethane.
Methanol and butan-1-ol both contain the same functional group. Predict whether they will have similar chemical reactions.
A compound contains a carboxyl functional group. Predict whether it will react more like ethanol or ethanoic acid.
C6.2j Describe the separation of crude oil by fractional distillation
What process is used to separate crude oil?
Where in a fractionating column do the highest boiling point fractions condense?
Explain why crude oil can be separated by fractional distillation.
Explain why different fractions condense at different heights in the fractionating column.
A hydrocarbon condenses near the bottom of a fractionating column. What can you conclude about its boiling point?
Explain why refinery gases are collected at the top of the fractionating column.
C6.2k Explain the separation of crude oil by fractional distillation
Which type of force exists between alkane molecules?
What happens to intermolecular forces as alkane molecules increase in size?
Explain why larger hydrocarbons have higher boiling points.
Explain why smaller hydrocarbons leave the fractionating column nearer the top.
A hydrocarbon has a boiling point of 320 °C. Predict where it will condense in the fractionating column.
Explain why methane has a much lower boiling point than hexadecane.
C6.2l Describe the fractions as largely a mixture of compounds of formula CₙH₂ₙ₊₂ which are members of the alkane homologous series
What is the general formula of the alkane homologous series?
Which homologous series makes up most compounds in crude oil fractions?
Explain why crude oil fractions are described as mixtures rather than pure substances.
Explain how all alkanes in a homologous series are chemically similar.
Which alkane has the molecular formula C₆H₁₄?
A hydrocarbon has the formula C₁₂H₂₆. Identify the homologous series it belongs to.
C6.2m Recall that crude oil is a main source of hydrocarbons and is a feedstock for the petrochemical industry
What is the main source of hydrocarbons?
What is meant by a feedstock?
Explain why crude oil is important to the petrochemical industry.
Explain why hydrocarbons from crude oil are used to make many useful products.
Name one product made using hydrocarbons from crude oil other than fuels.
Explain why crude oil is described as a feedstock rather than just a fuel.
C6.2n Explain how modern life is crucially dependent upon hydrocarbons and recognise that crude oil is a finite resource
What is meant by a finite resource?
Name one everyday use of hydrocarbons other than as fuels.
Explain why modern life depends heavily on hydrocarbons.
Explain why crude oil is described as a finite resource.
A country continues to use crude oil faster than new reserves are formed. Explain why this is unsustainable.
Explain why alternatives to crude oil are becoming increasingly important.
C6.2o Describe the production of materials that are more useful by cracking
What is cracking?
Which type of hydrocarbon is always produced during cracking?
Explain why long-chain hydrocarbons are cracked.
Explain why cracking is an important industrial process.
A refinery has a surplus of long-chain hydrocarbons but a high demand for petrol. Explain why cracking is carried out.
A long-chain alkane is cracked. Predict the types of products that will be formed.
C6.2p Recall that a chemical cell produces a potential difference until the reactants are used up
What does a chemical cell produce?
When does a chemical cell stop producing a potential difference?
Explain how a chemical cell produces a potential difference.
Explain why a chemical cell eventually stops working.
A battery no longer produces a voltage. Explain why.
Explain why replacing the reactants allows a chemical cell to produce a potential difference again.
C6.2q Evaluate the advantages and disadvantages of hydrogen/oxygen and other fuel cells for given uses
Which two reactants are used in a hydrogen/oxygen fuel cell?
What is the only chemical product of a hydrogen/oxygen fuel cell?
Explain one advantage of hydrogen/oxygen fuel cells compared with petrol engines.
Explain one disadvantage of hydrogen/oxygen fuel cells.
A bus company wants to reduce air pollution in a city centre. Explain one reason why hydrogen fuel cells may be a suitable choice.
Evaluate whether hydrogen/oxygen fuel cells are more suitable than petrol engines for cars, giving one advantage and one disadvantage.
C6.3a Interpret evidence for how it is thought the atmosphere was originally formed
What process is thought to have formed the Earth's early atmosphere?
Which gas made up most of the Earth's early atmosphere?
Explain why scientists think the early atmosphere contained very little oxygen.
Explain how volcanic activity contributed to the formation of the Earth's early atmosphere.
Evidence shows that modern volcanoes release carbon dioxide, water vapour and nitrogen. Explain how this supports theories about the Earth's early atmosphere.
Explain why scientists use evidence from rocks and volcanoes to develop models of the Earth's early atmosphere.
C6.3b Describe how it is thought an oxygen-rich atmosphere developed over time
Which organisms first released oxygen into the atmosphere?
Which process carried out by these organisms released oxygen?
Explain why atmospheric oxygen levels increased over millions of years.
Explain how photosynthesis changed the composition of the Earth's atmosphere.
Explain why carbon dioxide levels fell as photosynthetic organisms became more abundant.
Scientists discover evidence of early photosynthetic organisms. Explain how this supports the development of an oxygen-rich atmosphere.
C6.3c Describe the greenhouse effect in terms of the interaction of radiation with matter within the atmosphere
What type of radiation from the Sun passes through the Earth's atmosphere?
Which type of radiation emitted by the Earth is absorbed by greenhouse gases?
Explain how greenhouse gases warm the Earth.
Explain why the natural greenhouse effect is important for life on Earth.
Explain what happens to infrared radiation after it is absorbed by greenhouse gases.
Explain why increasing the concentration of greenhouse gases increases the Earth's average temperature.
C6.3d Evaluate the evidence for additional anthropogenic (human activity) causes of climate change and describe the uncertainties in the evidence base
What does the term anthropogenic mean?
Which human activity has caused a large increase in atmospheric carbon dioxide?
Explain why burning fossil fuels is linked to climate change.
Explain why predictions of future climate change contain uncertainties.
Scientists observe increasing atmospheric carbon dioxide alongside increasing fossil fuel use. Explain what this evidence suggests.
Explain why climate scientists continue to collect evidence even though there is strong evidence that human activity contributes to climate change.
C6.3e Describe the potential effects of increased levels of carbon dioxide and methane on the Earth's climate and how these effects may be mitigated
Name one greenhouse gas other than carbon dioxide.
State one possible effect of climate change.
Explain how methane contributes to climate change.
Explain one method used to reduce greenhouse gas emissions.
Explain how planting trees can help reduce atmospheric carbon dioxide.
A country replaces coal-fired power stations with renewable energy. Explain how this helps to mitigate climate change.
C6.3f Describe the major sources of carbon monoxide, sulfur dioxide, oxides of nitrogen and particulates in the atmosphere and explain the problems caused by increased amounts of these substances
Which poisonous gas is produced by incomplete combustion?
Which pollutant is mainly responsible for acid rain?
Explain how oxides of nitrogen are formed in vehicle engines.
Explain why particulates can cause health problems.
A diesel engine produces large amounts of particulates. Explain one problem this may cause.
Explain why catalytic converters reduce harmful emissions from petrol vehicles.
C6.3g Describe the principal methods for increasing the availability of potable water in terms of the separation techniques used
What is meant by potable water?
Which separation technique is used to produce potable water from salt water?
Explain why ground water usually requires less treatment than waste water.
Explain why desalination is more energy-intensive than treating ground water.
Compare the ease of treatment of waste water, ground water and salt water.
A region can obtain drinking water from ground water, treated waste water or sea water. Select the source that requires the least treatment to become potable and explain your answer.