AQA GCSE Trilogy Chemistry Paper 1 Higher June 2025 question paper 8464/C/1H

A teacher demonstrated the electrolysis of copper chloride solution.

Figure 1 shows the apparatus.

The teacher measured the mass of the negative electrode every 60 seconds.

Chlorine gas is given off during the electrolysis of copper chloride solution.

Chlorine gas is poisonous.

Give one way of reducing the risk of harm.

Table 1 shows the results.

Plot the data from Table 1 on Figure 2.

Draw a line of best fit.

The first point has been plotted for you.

A student made the hypothesis:

‘The negative electrode will increase by a constant mass every 60 seconds.’

How do the results in Table 1 show that the hypothesis is not correct?

25 cm³ of the solution of copper chloride contained 5.5 g of copper chloride.

Calculate the concentration of the solution in g/dm³.

The teacher also electrolysed potassium chloride solution.

Hydrogen gas was given off at the negative electrode.

Why was hydrogen gas given off?

Tick () one box.

A student investigated an exothermic reaction.

The student reacted solid calcium oxide with water to produce calcium hydroxide.

What is meant by an ‘exothermic’ reaction?

The formula of calcium hydroxide is Ca(OH)₂

Calculate the percentage by mass of oxygen in calcium hydroxide.

Relative atomic mass (A_r): O = 16

Relative formula mass (M_r): Ca(OH)₂ = 74

When solid calcium oxide is added to water, the temperature of the reaction mixture changes.

Plan a method to investigate how changing the mass of calcium oxide affects the temperature change of the reaction mixture.

This question is about atoms, ions and elements.

Figure 3 shows the results of the alpha particle scattering experiment.

In the experiment, alpha particles were fired at gold foil.

Alpha particles are positively charged.

What two conclusions were made from the results?

Tick () two boxes.

Particle X consists of:

• 35 protons

• 44 neutrons

• 36 electrons.

Why is particle X not an atom?

Answer in terms of subatomic particles.

Which is the correct representation of particle X ?

Use the periodic table.

Tick () one box.

Group 7 elements are known as the halogens.

Table 2 shows the boiling points of some Group 7 elements.

Explain the increase in the boiling points of the Group 7 elements going down the group.

Chlorine reacts with fluorine to form a compound with the formula ClF₃

What is the type of bonding in the compound ClF₃?

Chlorine reacts with a solution of sodium bromide.

Complete the word equation for the reaction.

Explain why Group 7 elements become less reactive going down the group.

This question is about metals.

Iron is extracted from iron oxide by reduction with carbon.

Why can iron be extracted by reduction with carbon?

Answer in terms of reactivity.

Aluminium is extracted by the electrolysis of aluminium oxide.

Figure 4 shows the apparatus used to extract aluminium.

Explain why a mixture of aluminium oxide and cryolite is used as the electrolyte instead of only aluminium oxide.

Oxygen gas is produced at the positive electrode.

Write a balanced half equation for the production of oxygen at the positive electrode.

Chromium is extracted by reacting chromium oxide with aluminium.

The equation for the reaction is:

Which substance in the equation is reduced?

Table 3 shows the relative cost of extracting equal masses of aluminium, chromium and iron.

Give one reason for the difference in the cost of extracting aluminium and iron.

Use Table 3.

Give one reason for the difference in the cost of extracting aluminium and chromium

Use Table 3.

Metals are mixed together to form alloys.

Explain why alloys are harder than pure metals.

This question is about hydrogen chloride (HC l) and hydrogen chlorate (HOC l).

Hydrogen chloride and hydrogen chlorate both form acids when dissolved in water.

Hydrogen chloride gas dissolves in water to form hydrochloric acid.

Give the state symbols for:

• hydrogen chloride

• water

• hydrochloric acid.

A solution of hydrochloric acid has:

• a concentration of H⁺ ions of 3.16 × 10⁻³ mol/dm³.

What is the concentration of H⁺ ions in a solution of hydrochloric acid that has a pH of 3.5?

Figure 5 shows the outer shells in one molecule of hydrogen chlorate (HOC l).

Complete the dot and cross diagram to show the electrons in the outer shells.

Figure 5

Hydrogen chlorate dissolves in water to form a weak acid.

Explain why a weak acid has a higher pH than a strong acid of the same concentration.

Hydrogen chloride is produced in the reaction between methane and chlorine.

Figure 6 represents the equation for the reaction.

Table 4 shows the bond energies.

Calculate the overall energy change for the reaction.

Some reactions appear to involve a change in mass.

A student investigated the change in mass when solids were heated.

Figure 7 shows the apparatus.

The student determined the mass of the contents of the crucible at regular intervals.

The student used a Bunsen burner instead of a water bath to heat the crucible.

Suggest one reason why.

The student planned to heat:

• 0.01 mol of magnesium

• 0.01 mol of magnesium carbonate.

The equations for the reactions are:

Figure 8 shows the student’s predicted results.

Look at Figure 8.

Explain the two trends for the first 3 minutes.

Magnesium carbonate

Figure 8 shows that both reactions are complete after 5 minutes.

Why is the final mass of the contents of the crucible the same for both reactions?

The student heated magnesium carbonate.

Figure 9 shows the results.

The student concluded:

‘The difference between the predicted results and the actual results is caused by solid escaping from the crucible.’

Give one reason why the results show the student is not correct.

Iron reacts with steam (H₂O) to produce an oxide of iron and hydrogen gas.

0.120 moles of iron reacts with 0.160 moles of steam.

Determine the balanced equation for the reaction.

You should determine:

• the simplest whole number mole ratio of Fe: H₂O

• the formula of the iron oxide produced.

Balanced equation for the reaction:

This question is about bonding and structures.

Figure 10 represents two models of sodium chloride.

Give two limitations of model A compared with model B.

Aluminium sulfate consists of the ions:

What is the formula of aluminium sulfate?

Metals have metallic bonding.

Suggest one reason why aluminium metal conducts electricity better than sodium metal.

Silicon dioxide and the polymer poly(ethene) are solid substances.

Compare silicon dioxide with the polymer, poly(ethene).

Answer in terms of structure and bonding.