AQA GCSE Chemistry Paper 2 Higher November 2021 question paper 8462/2H

This question is about fuels and energy. Figure 1 shows the percentage of electricity generated in the UK between 2007 and 2017 using:

• oil

• solar energy.

Describe the changes in the percentage of electricity generated in the UK between 2007 and 2017 using:

• oil

• solar energy.

Use data from Figure 1 in your answer.

Oil contains carbon and some sulfur. When oil is burned, the products of combustion may be released into the atmosphere. Explain the environmental effects of releasing these products of combustion into the atmosphere.

Suggest one reason why using solar energy is a more sustainable way of generating electricity than burning oil.

Solar energy may not be able to replace the generation of electricity from fossil fuels completely. Suggest two reasons why.

This question is about alkanes. Table 1 shows information about some alkanes.

Plot the data from Table 1 on Figure 2.

Predict the boiling point X of the alkane with seven carbon atoms in a molecule. Use Table 1 and Figure 2.

Figure 2 is not suitable to show the boiling point of the alkane with three carbon atoms in a molecule. Suggest one reason why.

What is the state at 20 °C of the alkane with four carbon atoms in a molecule? Use Table 1.

Table 1 is repeated below.

The alkane with nine carbon atoms in a molecule is called nonane.

Complete the formula of nonane.

Nonane will condense lower in a fractionating column during fractional distillation than the other alkanes in Table 1. Explain why. You should refer to the temperature gradient in the fractionating column.

This question is about paper chromatography. A food colouring contains a dye.

Plan an investigation to determine the R_f value for the dye in this food colouring.

Your plan should include the use of:

• a beaker

• a solvent

• chromatography paper.

Two students investigated a dye in a food colouring using paper chromatography. Each student did the investigation differently. The R_f values they determined for the same dye were different. How did the students’ investigations differ? Tick (✓) one box.

Paper chromatography involves a stationary phase. What is the stationary phase in paper chromatography? Tick (✓) one box.

This question is about poly(ethene) and polyesters.

Poly(ethene) is produced from ethene. Figure 3 shows part of the displayed structural formula equation for the reaction. Complete Figure 3.

Poly(ethene) is a thermosoftening polymer. Suggest why poly(ethene) is easier to recycle than thermosetting polymers.

Ethene produces different forms of poly(ethene). How can different forms of poly(ethene) be produced from ethene?

Two different forms of poly(ethene) are:

• high density poly(ethene) (HDPE)

• low density poly(ethene) (LDPE).

Figure 4 represents part of the structures of HDPE and LDPE.

Figure 4

Explain why HDPE has a higher density than LDPE.

Figure 5 shows three monomers, A, B and C. Monomer A can react with monomer B and with monomer C to produce polyesters.

Figure 5

Draw a circle on Figure 5 around an alcohol functional group.

Complete Table 2 to show the formula of the small molecule produced when:

• monomer A reacts with monomer B

• monomer A reacts with monomer C.

This question is about fertilisers. Some fertilisers are described as NPK fertilisers because they contain three elements needed for healthy plant growth.

Which two compounds each contain two of these elements? Tick (✓) two boxes.

Rocks containing calcium phosphate are treated with acid to produce soluble salts that can be used as fertilisers. Name the soluble salts produced when calcium phosphate reacts with:

• nitric acid

• phosphoric acid.

Ammonium sulfate is a compound in fertilisers. Ammonium sulfate can be made using an industrial process or in the laboratory. In the industrial process, the following steps are used.

1. React streams of ammonia solution and sulfuric acid together.

2. Evaporate the water by passing the solution down a warm column.

3. Collect dry crystals continuously at the bottom of the column.

In the laboratory, the following steps are used.

1. React ammonia solution and sulfuric acid in a conical flask.

2. Evaporate water from the solution until crystals start to form.

3. Leave to cool and crystallise further.

4. Separate the crystals using filtration.

5. Dry the crystals between pieces of filter paper.

Evaluate the two methods for producing a large mass of ammonium sulfate.

This question is about cycloalkenes. Cycloalkenes are ring-shaped hydrocarbon molecules containing a double carbon-carbon bond. Cycloalkenes react in a similar way to alkenes.

Describe a test for the double carbon-carbon bond in cycloalkene molecules. Give the result of the test.

Table 3 shows the name and formula of three cycloalkenes.

Determine the general formula for cycloalkenes.

Figure 6 shows the displayed structural formula of cyclohexene, C₆H₁₀

Chlorine reacts with cyclohexene to produce a compound with the formula C₆H₁₀Cl₂

Complete Figure 7 to show the displayed structural formula of C₆H₁₀Cl₂

Figure 7

Calculate the percentage by mass of chlorine in a molecule of C₆H₁₀Cl₂ Relative atomic masses (A_r): H = 1 C = 12 Cl = 35.5

Potash alum is a chemical compound. The formula of potash alum is KAl(SO₄)₂

Give a test to identify the Group 1 metal ion in potash alum. You should include the result of the test.

Name one instrumental method that could identify the Group 1 metal ion and show the concentration of the ion in a solution of potash alum.

A student identifies the other metal ion in potash alum. The student tests a solution of potash alum by adding sodium hydroxide solution until a change is seen.

Give the result of this test.

This test gives the same result for several metal ions. What additional step is needed so that the other metal ion in potash alum can be identified? Give the result of this additional step.

Describe a test to identify the presence of sulfate ions in a solution of potash alum. Give the result of the test.

This question is about copper and alloys of copper. Solders are alloys used to join metals together. Some solders contain copper. Table 4 shows information about three solders, A, B and C.

Solder B and solder C are now used more frequently than solder A for health reasons. Suggest one reason why. Use Table 4.

Suggest one reason why solders B and C have different melting points. Use Table 4.

Copper can be obtained by:

• processing copper ores

• recycling scrap copper.

Suggest three reasons why recycling scrap copper is a more sustainable way of obtaining copper than processing copper ores.

Copper is extracted from low-grade ores by phytomining.

Describe how copper is extracted from low-grade ores by phytomining.

Phytomining has not been widely used to extract copper. Suggest two reasons why.

A student investigated how a change in concentration affects the rate of the reaction between zinc powder and sulfuric acid. The equation for the reaction is:

This is the method used.

1. Pour 50 cm³ of sulfuric acid of concentration 0.05 mol/dm³ into a conical flask.

2. Add 0.2 g of zinc powder to the conical flask.

3. Put the stopper in the conical flask.

4. Measure the volume of gas collected every 30 seconds for 5 minutes.

5. Repeat steps 1 to 4 with sulfuric acid of concentration 0.10 mol/dm³

Figure 8 shows the apparatus used.

The student made an error in setting up the apparatus in Figure 8. What error did the student make?

The student corrected the error. Figure 9 shows the student’s results.

Explain why the lines of best fit on Figure 9 become horizontal.

How does Figure 9 show that zinc powder reacts more slowly with 0.05 mol/dm³ sulfuric acid than with 0.10 mol/dm³ sulfuric acid?

Determine the rate of the reaction for 0.05 mol/dm³ sulfuric acid at 80 seconds. Show your working on Figure 9. Give your answer to 2 significant figures.

The activation energy for the reaction between zinc and sulfuric acid is lowered if a solution containing metal ions is added. What is the most likely formula of the metal ions added? Tick (✓) one box.

This question is about alkenes and alcohols. Ethene is an alkene produced from large hydrocarbon molecules. Large hydrocarbon molecules are obtained from crude oil by fractional distillation.

Name the process used to produce ethene from large hydrocarbon molecules.

Describe the conditions used to produce ethene from large hydrocarbon molecules.

Ethanol can be produced from ethene and steam. The equation for the reaction is:

The forward reaction is exothermic.

Explain how the conditions for this reaction should be chosen to produce ethanol as economically as possible.

Ethanol can also be produced from sugar solution by adding yeast. Name this process.

Butanol can be produced from sugar solution by adding bacteria. Sugar solution is broken down in similar ways by bacteria and by yeast. Suggest the reaction conditions needed to produce butanol from sugar solution by adding bacteria.

Ethanol and butanol can be used as fuels for cars.

A car needs an average of 1.95 kJ of energy to travel 1 m Ethanol has an energy content of 1300 kilojoules per mole (kJ/mol). Calculate the number of moles of ethanol needed by the car to travel 200 km

When butanol is burned in a car engine, complete combustion takes place. Write a balanced equation for the complete combustion of butanol. You do not need to include state symbols.