AQA GCSE Chemistry Paper 1 Higher November 2020 question paper 8462/1H

This question is about structure and bonding.

Which two substances have intermolecular forces between particles? Tick (✓) two boxes.

Table 1 shows the structures of three compounds.

Compare the structure and bonding of the three compounds:

• carbon dioxide

• magnesium oxide

• silicon dioxide.

This question is about metals and the reactivity series.

Which two statements are properties of most transition metals? Tick (✓) two boxes.

A student added copper metal to colourless silver nitrate solution. The student observed:

• pale grey crystals forming

• the solution turning blue.

Explain how these observations show that silver is less reactive than copper.

A student is given three metals, X, Y and Z to identify. The metals are magnesium, iron and copper. Plan an investigation to identify the three metals by comparing their reactions with dilute hydrochloric acid. Your plan should give valid results.

Metal M has two isotopes. Table 2 shows the mass numbers and percentage abundances of the isotopes.

Calculate the relative atomic mass (A_r) of metal M. Give your answer to 1 decimal place.

This question is about silver iodide. Silver iodide is produced in the reaction between silver nitrate solution and sodium iodide solution. The equation for the reaction is: AgNO₃(aq) + NaI(aq) → AgI(s) + NaNO₃(aq)

A student investigated the law of conservation of mass. This is the method used.

1. Pour silver nitrate solution into a beaker labelled A.

2. Pour sodium iodide solution into a beaker labelled B.

3. Measure the masses of both beakers and their contents.

4. Pour the solution from beaker B into beaker A.

5. Measure the masses of both beakers and their contents again.

Table 3 shows the student’s results.

Explain how the results demonstrate the law of conservation of mass. You should use data from Table 3 in your answer.

Suggest how the student could separate the insoluble silver iodide from the mixture at the end of the reaction.

The student purified the separated silver iodide. This is the method used.

1. Rinse the silver iodide with distilled water.

2. Warm the silver iodide.

Suggest one impurity that was removed by rinsing with water.

Suggest why the student warmed the silver iodide.

Calculate the percentage atom economy for the production of silver iodide in this reaction. The equation for the reaction is: AgNO₃(aq) + NaI(aq) → AgI(s) + NaNO₃(aq) Give your answer to 3 significant figures. Relative formula masses (M_r): AgNO₃ = 170 NaI = 150 AgI = 235 NaNO₃ = 85

Give one reason why reactions with a high atom economy are used in industry.

This question is about electrolysis. A student investigated the electrolysis of copper chromate solution. Copper chromate solution is green. Copper chromate contains:

• blue coloured Cu²⁺ ions

• yellow coloured CrO₄^2– ions.

Figure 1 shows the apparatus used.

The student switched the power supply on. The student observed the changes at each electrode. Table 4 shows the student’s observations.

Explain why the colour changed at the positive electrode.

The gas produced at the positive electrode was oxygen. The oxygen was produced from hydroxide ions. Name the substance in the solution that provides the hydroxide ions.

Describe how the solid forms at the negative electrode.

The student repeated the investigation using potassium iodide solution instead of copper chromate solution. Name the product at each electrode when potassium iodide solution is electrolysed. Negative electrode Positive electrode

This question is about the development of scientific theories. Figure 2 shows a timeline of some important steps in the development of the model of the atom.

The plum pudding model did not have a nucleus. Describe three other differences between the nuclear model of the atom and the plum pudding model.

Niels Bohr adapted the nuclear model. Describe the change that Bohr made to the nuclear model.

Mendeleev published his periodic table in 1869. Mendeleev arranged the elements in order of atomic weight. Mendeleev then reversed the order of some pairs of elements. A student suggested Mendeleev’s reason for reversing the order was to arrange the elements in order of atomic number. Explain why the student’s suggestion cannot be correct. Use Figure 2.

Give the correct reason why Mendeleev reversed the order of some pairs of elements.

This question is about displacement reactions.

The displacement reaction between aluminium and iron oxide has a high activation energy. What is meant by ‘activation energy’?

A mixture contains 1.00 kg of aluminium and 3.00 kg of iron oxide. The equation for the reaction is:

Show that aluminium is the limiting reactant. Relative atomic masses (A_r): O = 16 Al = 27 Fe = 56

Magnesium displaces zinc from zinc sulfate solution.

Complete the ionic equation for the reaction. You should include state symbols.

Explain why the reaction between magnesium atoms and zinc ions is both oxidation and reduction.

The reaction between hydrogen and oxygen releases energy.

A student drew a reaction profile for the reaction between hydrogen and oxygen. Figure 3 shows the student’s reaction profile.

The student made two errors when drawing the reaction profile. Describe the two errors.

The reaction between hydrogen and oxygen in a hydrogen fuel cell is used to produce electricity. Hydrogen fuel cells and rechargeable cells are used to power some cars. Give two advantages of using hydrogen fuel cells instead of using rechargeable cells to power cars.

Reactions occur at the positive electrode and at the negative electrode in a hydrogen fuel cell. Write a half equation for one of these reactions.

The three states of matter can be represented by a simple particle model. Figure 4 shows a simple particle model for hydrogen gas.

Give two limitations of this simple particle model for hydrogen gas.

The hydrogen gas needed to power a car for 400 km would occupy a large volume. Suggest one way that this volume can be reduced.

The energy needed for a car powered by a hydrogen fuel cell to travel 100 km is 58 megajoules (MJ). The energy released when 1 mole of hydrogen gas reacts with oxygen is 290 kJ The volume of 1 mole of a gas at room temperature and pressure is 24 dm³ Calculate the volume of hydrogen gas at room temperature and pressure needed for the car to travel 100 km

This question is about the halogens. Table 5 shows the melting points and boiling points of some halogens.

What is the state of bromine at 0 °C and at 100 °C? Tick (✓) one box. State at 0 °C State at 100 °C

Explain the trend in boiling points of the halogens shown in Table 5.

Why is it not correct to say that the boiling point of a single bromine molecule is 59 °C?

Iron reacts with each of the halogens in their gaseous form. Figure 5 shows the apparatus used.

Give one reason why this experiment should be done in a fume cupboard.

Explain why the reactivity of the halogens decreases going down the group.

A teacher investigated the reaction of iron with chlorine using the apparatus in Figure 5. The word equation for the reaction is: iron + chlorine → iron chloride The teacher weighed:

• the glass tube

• the glass tube and iron before the reaction

• the glass tube and iron chloride after the reaction.

Table 6 shows the teacher’s results.

Calculate the simplest whole number ratio of: moles of iron atoms moles of chlorine atoms Determine the balanced equation for the reaction. Relative atomic masses (A_r): Cl = 35.5 Fe = 56

Equation for the reaction

This question is about citric acid (C₆H₈O₇). Citric acid is a solid. A student investigated the temperature change during the reaction between citric acid and sodium hydrogencarbonate solution. This is the method used.

1. Pour 25 cm³ of sodium hydrogencarbonate solution into a polystyrene cup.

2. Measure the temperature of the sodium hydrogencarbonate solution.

3. Add 0.20 g of citric acid to the polystyrene cup.

4. Stir the solution.

5. Measure the temperature of the solution.

6. Repeat steps 3 to 5 until a total of 2.00 g of citric acid has been added.

The student plotted the results on a graph. Figure 6 shows the student’s graph.

Figure 6 shows an anomalous point when 0.60 g of citric acid was added. This was caused by the student making an error. The student correctly:

• measured the mass of the citric acid

• read the thermometer

• plotted the point.

Suggest one reason for the anomalous point.

Explain the shape of the graph in terms of the energy transfers taking place. You should use data from Figure 6 in your answer.

A second student repeated the investigation using a metal container instead of the polystyrene cup. The container and the cup were the same size and shape. Sketch a line on Figure 6 to show the second student’s results until 1.00 g of citric acid had been added. The starting temperature of the solution was the same. Explain your answer.

The student used a solution of citric acid to determine the concentration of a solution of sodium hydroxide by titration.

The student made 250 cm³ of a solution of citric acid of concentration 0.0500 mol/dm³ Calculate the mass of citric acid (C₆H₈O₇) required. Relative atomic masses (A_r): H = 1 C = 12 O = 16

This is part of the method the student used for the titration.

1. Measure 25.0 cm³ of the sodium hydroxide solution into a conical flask using a pipette.

2. Add a few drops of indicator to the flask.

3. Fill a burette with citric acid solution.

Describe how the student would complete the titration.

Give two reasons why a burette is used for the citric acid solution.

13.3 cm³ of 0.0500 mol/dm³ citric acid solution was needed to neutralise 25.0 cm³ of sodium hydroxide solution. The equation for the reaction is:

Calculate the concentration of the sodium hydroxide solution in mol/dm³

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