AQA GCSE Trilogy Chemistry Paper 2 Higher June 2023 question paper 8464/C/2H

The combustion of fuels is a source of atmospheric pollutants.

Methane is a fuel. Balance the equation for the combustion of methane.

Many fuels are mixtures. Petrol and diesel are mixtures of hydrocarbons. Table 1 shows properties of petrol and of diesel.

Compare the properties of petrol and diesel. Use Table 1.

The gases released when a fuel is burned in car engines may include:

• oxides of nitrogen

• carbon monoxide

• water vapour.

Which chemical element do all these gases contain? Tick (✓) one box.

When diesel burns in car engines, oxides of nitrogen are produced. Where does the nitrogen come from?

When diesel burns, particulates may be produced. What environmental effect do particulates from burning diesel cause?

Carbon monoxide may be produced when diesel burns. Give one reason why carbon monoxide is difficult to detect.

Explain why water vapour and not liquid water is produced when diesel burns.

Sulfur is a common impurity in diesel. Explain why this causes an environmental problem.

Chromatography is used to separate mixtures.

Chromatography involves a mobile phase and one other phase.

What is the other phase in chromatography? Tick (✓) one box.

Why do the substances in the mixture separate in the mobile phase?

How many spots will be produced on the chromatogram of a pure compound?

In a chromatography experiment, a blue colour moved 4.77 cm. The solvent moved 5.30 cm. Calculate the R_f value for the blue colour.

Black ink is a mixture of several colours. Plan an experiment using paper chromatography to:

• separate the colours in black ink

• identify the colours from their R_f values.

Crude oil is a mixture of many different compounds.

Give two reasons why crude oil is not a formulation.

Describe how crude oil is separated into fractions.

The fractions from crude oil contain alkanes. Explain why alkanes are cracked.

Cracking produces a mixture of products.

An equation for cracking decane (C₁₀H₂₂) is:

Describe a test to identify the gas produced in the reaction.

Alkenes are produced in cracking. The general formula for the homologous series of alkenes is C_nH_2n Which formula represents an alkene? Tick (✓) one box.

Some types of water contain dissolved substances.

A student investigated the mass of dissolved solids in distilled water and in sea water. Figure 1 shows the apparatus.

This is the method used.

1. Weigh an evaporating basin.

2. Add 20 cm³ of distilled water to the evaporating basin.

3. Weigh the evaporating basin and the water sample.

4. Heat the water sample for 2 minutes.

5. Weigh the evaporating basin and contents.

6. Repeat steps 1 to 5 two more times.

7. Repeat steps 1 to 6 with sea water.

The method used by the student did not give valid results. Describe one improvement the student could make to obtain valid results.

A different student used a method which gave valid results.

Table 2 shows the results.

Calculate the value X for the mass of dissolved solids in sea water in Test 2.

The student concludes that distilled water is pure. Describe a test to confirm that distilled water is pure.

Tap water is potable.

A stage in the production of potable water is sterilising. A gas is used to sterilise water. The equation for the reaction is:

What is meant by the symbol ?

The reaction is at equilibrium. The reaction is exothermic. What happens to the equilibrium position when the temperature is increased? Tick (✓) one box.

Describe a test to identify the gas used to sterilise water.

Another stage in the production of potable water is filtering. Explain why potable water contains dissolved solids after filtering.

An increase of greenhouse gases in the Earth’s atmosphere is causing global warming. Global warming is causing global climate change.

Give one effect of global climate change.

Explain how greenhouse gases cause global warming.

Explain how planting trees reduces global warming.

A student investigated the rate of decomposition of hydrogen peroxide using three different catalysts:

• manganese dioxide

• copper oxide

• zinc oxide.

Figure 2 shows the apparatus.

This is the method used.

1. Measure 20 cm³ of hydrogen peroxide solution into a flask.

2. Add 0.5 g of manganese dioxide catalyst to the flask.

3. Attach a gas syringe to the flask.

4. Measure the volume of oxygen produced every 30 seconds for 180 seconds.

5. Repeat steps 1 to 4 two more times.

6. Repeat steps 1 to 5 using copper oxide catalyst.

7. Repeat steps 1 to 5 using zinc oxide catalyst.

The equation for the decomposition of hydrogen peroxide is:

Describe a test to identify the gas produced in the reaction.

Using 10 cm³ of hydrogen peroxide solution gives less accurate results than using 20 cm³ of hydrogen peroxide solution of the same concentration. Explain why.

Suggest one possible source of systematic error in the investigation.

Table 3 shows the results for manganese dioxide catalyst.

Figure 3 shows a graph of the results with copper oxide catalyst and with zinc oxide catalyst.

Complete Figure 3. You should:

• plot the data from Table 3

• draw a line of best fit.

The first point has been plotted for you.

Which catalyst gives the fastest rate of reaction? Give one reason for your answer. Use the completed Figure 3.

The rate of reaction is not dependent on the volume of hydrogen peroxide solution. Explain why.

Figure 4 shows the results from a different investigation.

Determine the rate of reaction at 20 seconds. Show your working on Figure 4. Give your answer to 3 significant figures.