AQA GCSE Trilogy Chemistry Paper 2 Higher November 2020 question paper 8464/C/2H

This question is about the Earth’s resources.

When most fuels burn carbon dioxide is produced.

Balance the equation for the combustion of propane.

Describe the test for carbon dioxide. Give the result of the test.

Propane can be cracked to produce propene and hydrogen. Complete the symbol equation for the reaction.

Describe the test for hydrogen. Give the result of the test.

Propene is an alkene. Describe the test for alkenes. Give the colour change in the test.

Some students investigated the effect of temperature on the rate of reaction.

The students reacted sodium thiosulfate solution with hydrochloric acid. This is the method used.

1. Use a beaker to measure 50 cm³ of heated sodium thiosulfate solution into a

conical flask.

2. Measure the temperature of the room.

3. Put the conical flask on a black cross drawn on a piece of paper.

4. Start a timer.

5. Use the same beaker to measure 10 cm³ of hydrochloric acid into the conical flask.

6. Stop the timer when the cross is no longer visible.

The students repeated the experiment at a different room temperature. Figure 1 shows the apparatus.

The method contains errors and does not produce accurate results.

Describe a method the students should use to produce accurate results. You do not need to write about safety precautions.

Some students investigated the effect of temperature on the rate of a different reaction. They recorded the loss of mass from their apparatus at 40 °C Figure 2 shows the results.

Calculate the mean rate of reaction between 1 minute and 3 minutes at 40 °C Use Figure 2 and the equation:

Draw a curve on Figure 2 for the results you would expect at a temperature of

This question is about pollutants.

Waste water has harmful substances removed before being released into the environment. Complete the sentences. Agricultural waste water requires the removal of harmful

Industrial waste water may require the removal of harmful

How is sewage sludge treated before being released into the environment? Tick (✓) one box.

Hydrocarbons are used to make polymers. Polymers are used to make plastic bags. In one year 8.0 billion plastic bags were used. The next year there was a charge for plastic bags and only 1.3 billion plastic bags were used. Calculate the percentage decrease in the number of plastic bags used.

Oxides of nitrogen are pollutants formed in car engines.

Give one problem oxides of nitrogen cause.

Figure 3 shows the mass of oxides of nitrogen produced from car engines from 1986 to 2016.

Suggest why the mass of oxides of nitrogen produced from car engines increased and then decreased.

A student investigated the mass of dissolved solids in four water samples A, B, C and D. Figure 4 shows the apparatus used.

This is the method used.

1. Record the mass of a dry evaporating basin.

2. Pour 25 cm³ of water sample A into the evaporating basin.

3. Place the evaporating basin on the beaker for 10 minutes.

4. Record the mass of the evaporating basin and contents.

5. Repeat steps 1 to 4 with water sample A three more times.

6. Repeat steps 1 to 5 with water samples B, C and D.

What type of variable is the mass of dissolved solids? Tick (✓) one box.

The method produced an error in the mass recorded in step 4. Suggest what caused the error. How could the error be avoided?

Another student carried out the investigation correctly.

Table 1 shows the results.

Calculate value X in Table 1.

Which water sample has the greatest range of masses of dissolved solids? Give the reason for your answer.

Water companies measure the volume of water used by households in

25 cm³ of a different water sample contained 0.016 g of dissolved solids. Calculate the mass of dissolved solid in 1 m³ of this water sample.

Give your answer in standard form.

Mass (in standard form) = g

This question is about crude oil and alkanes.

Describe how crude oil is formed.

Describe how crude oil is separated into fractions by fractional distillation.

Table 2 shows the boiling points of three alkanes.

What is the general formula for alkanes?

Explain the trend in the boiling points of the alkanes.

A student investigated one property of the alkanes C₅H₁₂, C₁₀H₂₂ and C₁₅H₃₂ This is the method used.

1. Pour 20 cm³ of C₅H₁₂ into a separating funnel.

2. Open the tap of the separating funnel and start a timer.

3. Stop the timer when the level of C₅H₁₂ reaches line X.

4. Repeat steps 1 to 3 with C₁₀H₂₂ and C₁₅H₃₂

Figure 5 shows the apparatus used.

The level of C₅H₁₂ takes 6.4 seconds to reach line X. Predict the trend in times for the other two alkanes. Give one reason for your answer.

This question is about the Earth’s atmosphere.

Carbon dioxide is a greenhouse gas. The greenhouse effect happens in four stages. The four stages are: Stage A Carbon dioxide stops longer wavelength radiation escaping Stage B Radiation is absorbed by the Earth Stage C Longer wavelength radiation is emitted Stage D Shorter wavelength radiation enters the atmosphere What is the correct order of stages A, B, C and D ? Tick (✓) one box.

Figure 6 shows how the percentage of carbon dioxide in the Earth’s atmosphere has

changed over 4.6 billion years.

The mass of gas in Earth’s atmosphere remains constant at 5.15 × 10¹⁸ kg Determine the maximum mass of carbon dioxide that was in the Earth’s atmosphere. Use Figure 6.

Mass of carbon dioxide = kg

Describe the processes that have caused the main changes in the percentage of carbon dioxide in the Earth’s atmosphere over the last 4.6 billion years. Use Figure 6.

This question is about equilibrium.

Describe how a reaction reaches equilibrium.

Nitrogen dioxide gas reacts to form dinitrogen tetraoxide gas. The reaction is reversible. The equation for the reaction is:

Explain the effect on the equilibrium position of increasing the pressure.

Figure 7 shows the change in the percentage of dinitrogen tetroxide (N₂O₄) in the equilibrium mixture as the temperature of the equilibrium mixture is changed.

Explain the effect on the equilibrium position of increasing the temperature. Use Figure 7.