AQA GCSE Chemistry Paper 2 Higher June 2023 question paper 8462/2H

A student investigated the rate of the reaction between zinc and sulfuric acid. Hydrogen gas is produced during this reaction. Figure 1 shows the apparatus.

This is the method used.

1. Add 50 cm³ of sulfuric acid to a conical flask.

2. Add 2.0 g of zinc to the conical flask.

3. Quickly put a stopper in the conical flask and start a timer.

4. Measure the time taken to collect 20 cm³ of gas.

5. Repeat steps 1 to 4 three more times.

Suggest why the stopper must be put in the conical flask as quickly as possible in step 3.

The student calculated the rate of the reaction for each trial. Table 1 shows the results of the calculations.

Determine the mean time taken to collect 20 cm³ of gas. Do not include any anomalous results. Use the equation:

The student changed the investigation so that the mean time taken to collect 20 cm³ of gas was greater. Which two changes would increase the mean time taken to collect 20 cm³ of gas? Tick (✓) two boxes.

Hydrogen gas is produced during this reaction. Describe the test for hydrogen gas. Give the result of the test.

This question is about alcohols and carboxylic acids.

Alcohols are used as fuels. A student burned 1.00 g of six alcohols and determined the energy released from each. Table 2 shows the results.

Calculate the mass of ethanol that must be burned to release the same amount of energy as burning 1.00 g of heptanol.

The energy released in kJ/g varies with the number of carbon atoms in one molecule of each alcohol. Plot the data from Table 2 on Figure 2.

Estimate the energy released in kJ when 1.00 g of octanol (C₈H₁₇OH) is burned. Use Figure 2.

Carbon dioxide is produced when alcohols are burned. Carbon dioxide is identified by bubbling the gas through limewater.

Complete the sentence. Choose the answer from the box.

Limewater is an aqueous solution of.

Give the result of the test when carbon dioxide is bubbled through limewater.

Ethanoic acid can be produced from ethanol.

What is reacted with ethanol to produce ethanoic acid? Tick (✓) one box.

Ethanoic acid contains the functional group –COOH Complete the displayed structural formula of this functional group.

Ethanoic acid reacts with different compounds. Draw one line from each compound to a product of the reaction of the compound with ethanoic acid.

Product of the reaction

This question is about chemical analysis. Potassium bromide is used in medicine. A scientist tested a sample of medicine to show the presence of potassium ions and of bromide ions. The sample is soluble in water.

Plan a method the scientist could use to show that the sample of medicine contains potassium ions and bromide ions. The scientist has:

• a Bunsen burner

• a metal wire

• test tubes

• a dropping pipette

• distilled water

• dilute nitric acid

• silver nitrate solution.

You should give the results of the tests.

The scientist could also use an instrumental method to show the presence of potassium ions in the medicine.

Which instrumental method could be used to show the presence of potassium ions in the medicine?

Give one advantage of using this instrumental method instead of a chemical test.

This question is about greenhouse gases and climate change.

Carbon dioxide and methane are greenhouse gases.

Which of the following is also a greenhouse gas? Tick (✓) one box.

In the past 50 years, there has been an increase in:

• the world population

• the concentration of carbon dioxide in the atmosphere

• the concentration of methane in the atmosphere

• the mean temperature of the atmosphere at the Earth’s surface.

Most scientists think this information can be used to explain climate change.

Explain why the increase in world population may have caused the increase in the concentration of carbon dioxide in the atmosphere.

Explain why the increase in world population may have caused the increase in the concentration of methane in the atmosphere.

Describe two potential effects of the increase in the mean temperature of the atmosphere at the Earth’s surface.

The mean temperature of the atmosphere at the Earth’s surface has increased. Most scientists think that this has been caused by an increase in the concentration of greenhouse gases in the atmosphere. Give one reason why some scientists do not accept this theory.

Copper is extracted from metal ores. Chalcopyrite is a metal ore containing a compound with the formula CuFeS₂

CuFeS₂ reacts with oxygen to produce copper(II) sulfate and iron(II) sulfate. Complete the equation for this reaction. You should balance the equation.

Calculate the percentage by mass of copper in CuFeS₂ Relative atomic masses (A_r): S = 32 Fe = 56 Cu = 63.5

Describe a test to show the presence of copper(II) ions in a solution of copper(II) sulfate. Give the result of the test.

Copper can be extracted from low-grade ores by bioleaching. Describe what is meant by bioleaching.

This question is about chromatography.

A student investigated an orange food colouring using two different types of chromatography paper. The food colouring:

• contained a mixture of red and yellow dyes

• was soluble in water.

This is the method used.

1. Draw a start line on a piece of type A chromatography paper.

2. Put a spot of orange food colouring on the line.

3. Put the paper into a beaker containing water as a solvent.

4. Wait for the water to travel up the paper.

5. Measure the distance above the start line moved by the red and yellow dyes and the water.

6. Repeat steps 1 to 5 using type B chromatography paper.

Figure 3 shows how the student set up the apparatus.

The student made two mistakes when setting up the apparatus. Give two mistakes the student made.

Another student set up the apparatus correctly. Table 3 shows the results.

Determine value X in Table 3.

Changing the type of chromatography paper resulted in different R_f values for the red dye.

Explain why the R_f values for the red dye are different using the two types of chromatography paper. Use Table 3.

What other change to the investigation could result in a different R_f value for the red dye?

Manganese dioxide catalyses the decomposition of hydrogen peroxide solution. Oxygen and water are produced.

Explain how a manganese dioxide catalyst increases the rate of decomposition of hydrogen peroxide.

A student investigated the rate of this reaction. This is the method used.

1. Add 50 cm³ of 2.0 mol/dm³ hydrogen peroxide solution to a conical flask.

2. Add 1.0 g of manganese dioxide to the conical flask.

3. Place the conical flask on a balance and start a timer.

4. Record the total mass lost from the conical flask every 20 seconds for 180 seconds.

Explain why the mass of the conical flask and contents decreased.

Figure 4 shows the results for 50 cm³ of 2.0 mol/dm³ hydrogen peroxide solution and 1.0 g of manganese dioxide. A tangent to the line has been drawn at 75 seconds.

Determine the rate of reaction when the time was 75 seconds. Give your answer to 2 significant figures.

The results for 50 cm³ of 2.0 mol/dm³ hydrogen peroxide solution and 1.0 g of manganese dioxide are shown again on Figure 5.

The student repeated the investigation using 50 cm³ of 1.0 mol/dm³ hydrogen peroxide solution and 1.0 g of manganese dioxide. Sketch the expected results for 1.0 mol/dm³ hydrogen peroxide solution on Figure 5.

This question is about polymers.

Chloroethene can be used to produce an addition polymer called poly(chloroethene). The displayed structural formula of chloroethene is

Draw a circle around the functional group on the displayed structural formula that allows chloroethene to produce an addition polymer.

Complete the equation for the production of poly(chloroethene) from chloroethene.

Poly(ethene) can be strengthened with wood particles to make a building material. The building material consists of a wood particle reinforcement embedded in a poly(ethene) matrix. What general name is given to materials like this?

The amino acid beta-alanine has the formula

Beta-alanine polymerises to produce a polypeptide and a small molecule. Name the small molecule produced when beta-alanine polymerises.

An amino acid can be represented as:

The relative formula mass (M_r) of this amino acid is 75 Calculate the relative formula mass of the section of this amino acid molecule represented by

Relative atomic masses (A_r): H = 1 C = 12 N = 14 O = 16

Figure 6 represents part of a naturally occurring polymer molecule produced from glucose.

Draw a circle around the repeating unit in the polymer in Figure 6.

Suggest the identity of this polymer.

Figure 7 represents the structure of a naturally occurring polymer.

Give the general name for the four different monomers which make up the structure shown in Figure 7.

Name the shape of the structure shown in Figure 7.

This question is about reversible reactions.

When 4.68 g of hydrated copper sulfate changes into anhydrous copper sulfate:

• 2.99 g of anhydrous copper sulfate is produced

• 1.47 kJ of energy is taken in from the surroundings.

The equation for the reversible reaction is: hydrated copper sulfate ⇌ anhydrous copper sulfate + water

Calculate the maximum mass of water that can be produced from 11.7 g of hydrated copper sulfate.

15.0 g of anhydrous copper sulfate completely changes into hydrated copper sulfate when water is added.

Calculate the amount of energy transferred to the surroundings.

The gases nitrogen dioxide and dinitrogen tetroxide reach dynamic equilibrium in a sealed container. The equation for the reaction is:

nitrogen dioxide (brown) dinitrogen tetroxide (colourless) The forward reaction is exothermic.

What happens to the position of the equilibrium in this reaction if the temperature is increased?

Tick (✓) one box.

A teacher seals a brown-coloured mixture of nitrogen dioxide and dinitrogen tetroxide in a gas syringe. Figure 8 shows the sealed gas syringe.

Figure 8

The teacher pushes the syringe piston in. This increases the pressure in the gas syringe.

What is the colour of the mixture when a new equilibrium position is reached?

Tick (✓) one box.

Hydrogen iodide gas decomposes into hydrogen gas and iodine gas at high temperatures. The equation for the reaction is:

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

Suggest the effect of adding a catalyst on the equilibrium position of this reaction.

Copper forms coloured compounds. Hydrochloric acid is added to an aqueous solution of copper compound A. The word equation for the reaction is: copper compound A + hydrochloric acid ⇌ copper compound B + water (blue) (yellow)

The reaction mixture is green when both copper compounds are present in a solution at equilibrium. How can the equilibrium position be shifted to make the reaction mixture more yellow?

Tick (✓) one box.

The concentrations of the substances in this reaction do not change at dynamic equilibrium. Explain why.

This question is about fertilisers. Compounds of nitrogen (N), phosphorus (P) and potassium (K) are used as fertilisers to improve agricultural productivity. Table 4 shows information about three compounds, A, B and C, that can be used as fertilisers.

A scientist analysed the percentages of nitrogen, phosphorus and potassium in a soil. The percentages of nitrogen and of potassium in the soil were lower than the percentages needed for high agricultural productivity. There was sufficient phosphorus in the soil for high agricultural productivity. Evaluate the use of the compounds in Table 4 to improve the agricultural productivity of this soil.

How is potassium chloride (compound A) obtained from the Earth?

Name one other compound that could be used instead of potassium chloride (compound A) to give a similar improvement in agricultural productivity.

Nitric acid is needed to produce ammonium nitrate (compound B). Name a compound needed to produce nitric acid.

Phosphate rock contains phosphorus compounds. Plants absorb phosphorus from compounds dissolved in rainwater. Suggest why phosphate rock cannot be used directly as a fertiliser.

Phosphate rock can be treated with different acids to produce salts useful as fertilisers. Name the salts which are produced by treating phosphate rock with:

• sulfuric acid

• phosphoric acid.