AQA GCSE Chemistry Paper 1 Foundation November 2020 question paper 8462/1F

This question is about the elements in Group 7 of the periodic table. Table 1 shows the melting points and boiling points of some of the elements.

What is the state of bromine at 100 °C? Use Table 1. Tick (✓) one box.

What temperature does chlorine gas condense at to form a liquid? Use Table 1.

Complete the sentences.

This is because the size of the molecules increases so the

A teacher investigated the reaction of iron with chlorine. Figure 1 shows the apparatus used.

Why did the teacher do the investigation in a fume cupboard? Tick (✓) one box.

The word equation for the reaction is: iron + chlorine → iron chloride Iron chloride is a solid. The teacher weighed the glass tube and contents:

• before the reaction

• after the reaction.

What happened to the mass of the glass tube and contents during the reaction? Give one reason for your answer.

The mass of the glass tube and contents.

The teacher repeated the investigation with bromine gas and with iodine gas. Table 2 shows the results.

Fluorine is above chlorine in Group 7. Predict what you would observe when fluorine gas reacts with iron. Use Table 2.

Balance the equation for the reaction between iron and bromine.

2 Fe + _____ Br 2 → 2 FeBr 3

Calculate the relative formula mass (M_r) of FeBr₃ Relative atomic masses (A_r): Fe = 56 Br = 80

This question is about models of the atom.

Atoms were first thought to be tiny spheres that could not be divided. Which particle was discovered to change this model of the atom? Tick (✓) one box.

Figure 2 shows another model of the atom.

What is the name of this model of the atom?

A scientist fired particles at gold atoms. Some of these particles were scattered. The results led to a different model of the atom. Which type of particle was fired at the gold atoms? Tick (✓) one box.

Which scientist first suggested that electrons orbit the nucleus at specific distances? Tick (✓) one box.

The model of the atom used today has three subatomic particles:

• electrons

• neutrons

• protons.

Complete the sentences.

Atoms of the same element have the same atomic number because they have the

Atoms of the same element can have different mass numbers because they have

Atoms have no overall charge because they have

The radius of a nucleus is approximately 1 × 10^–14 m The radius of an atom is approximately 1 × 10^–10 m A teacher uses a ball of radius 1 cm to represent the nucleus. What could represent the atom on the same scale? Tick (✓) one box.

This question is about chemical reactions and energy. Hydrogen reacts with oxygen to produce water. This reaction releases energy.

Complete the word equation for the reaction. [1 mark hydrogen + oxygen → ____________

Figure 3 shows a reaction profile for the reaction between hydrogen and oxygen.

What do the labels W, X, Y and Z represent? Choose answers from the box.

The reaction between hydrogen and oxygen is used in a hydrogen fuel cell. What is the reason for using this reaction in a fuel cell? Tick (✓) one box.

A student investigated the voltage produced by a chemical cell. The student used different metals as the electrodes in the cell. The metals used were:

• copper

• iron

• magnesium.

Which two metal electrodes would produce the greatest voltage when used in the chemical cell? Give one reason for your answer.

This question is about electrolysis. A student investigated the hypothesis: ‘The electrolysis of a salt solution produces a metal at the negative electrode and a gas at the positive electrode.’

Figure 4 shows the apparatus used.

What observation would be made at each electrode if the hypothesis is correct?

Table 3 shows the student’s results.

Which salt solution in Table 3 does not match the student’s hypothesis? Give one reason why.

Give two reasons why graphite is used for the electrodes.

A different student investigated what happens during electrolysis. Figure 5 shows the apparatus.

The purple crystal contained:

• colourless positive ions

• purple coloured negative ions.

The purple crystal dissolved in the electrolyte solution.

What happens to the purple coloured ions? Give one reason for your answer. Tick (✓) one box.

This question is about aluminium.

Aluminium is a metal. Draw one line from each property of aluminium to the correct reason for that property.

Property Reason

Aluminium can be used to make alloys. What is meant by an ‘alloy’?

Aluminium is extracted from bauxite. Bauxite is a mixture which contains aluminium oxide.

Bauxite contains between 15% and 25% aluminium. Aluminium oxide always contains 53% aluminium. How does this show that bauxite is a mixture and not a compound?

The waste material from the bauxite is stored in lakes of mud. The lakes of mud are held in place by dams. Figure 6 shows one of these lakes.

Suggest two possible problems with storing the waste material in lakes of mud.

Aluminium is extracted by electrolysis. The aluminium oxide is mixed with cryolite and melted. The mixture is then electrolysed.

The formula of cryolite is Na₃AlF₆ Give the total number of atoms in the formula.

What is the reason for adding cryolite to the aluminium oxide? Tick (✓) one box.

Complete the sentences. Choose answers from the box.

When the molten aluminium oxide and cryolite mixture is electrolysed the product

This product reacts with the positive electrode because the positive electrode is

A sample of bauxite contains 25% aluminium. Calculate the maximum mass of aluminium that can be extracted from 300 000 kg of the sample of bauxite. Give your answer in standard form.

This question is about citric acid. Figure 7 represents one molecule of citric acid.

Complete the molecular formula of citric acid. Use Figure 7. C 6 H __ O __

What type of bonding is shown in Figure 7 ? Tick (✓) one box.

Figure 8 shows two representations of one molecule of citric acid, A and B.

Figure 8

Give two advantages of representation A compared with representation B. Advantages of A:

A student investigated the temperature change during the reaction between citric acid and sodium hydrogencarbonate solution. Citric acid is a solid. 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 0.25 g of citric acid to the 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.

Table 4 shows some of the student’s results.

How do the results in Table 4 show that the reaction is endothermic?

Three of the student’s results are plotted on Figure 9. A line of best fit for these points is drawn. Complete Figure 9. You should:

• plot the data from Table 4 on Figure 9

• draw a line of best fit through the points you have plotted

• extend your line of best fit to meet the line of best fit already drawn on Figure 9.

Determine the overall temperature change for the reaction. Use Figure 9.

What is the dependent variable in this investigation? Tick (✓) one box.

This question is about acids, bases and salts.

Zinc nitrate is a salt. A student produces zinc nitrate using an acid and a base.

Which acid should the student use to produce zinc nitrate? Tick (✓) one box.

Which is a base the student could use to produce zinc nitrate? Tick (✓) one box.

Name the salt with the formula MgBr₂

A student investigated how pH changes during a titration. This is the method used.

1. Pour 25.0 cm³ of hydrochloric acid into a beaker.

2. Measure the pH of the hydrochloric acid with a pH probe.

3. Add 1.0 cm³ of sodium hydroxide solution from a burette.

4. Swirl the mixture.

5. Measure the pH of the mixture.

6. Repeat steps 3 to 5 until a total of 30.0 cm³ of sodium hydroxide solution has been added.

Figure 10 shows the student’s results.

Describe how the pH of the mixture changes as sodium hydroxide solution is added to hydrochloric acid. Use data from Figure 10 in your answer.

What volume of sodium hydroxide solution is needed to neutralise 25.0 cm³ of hydrochloric acid? Use Figure 10.

Figure 11 shows the colour of universal indicator at different pH values.

The student could have used universal indicator instead of a pH probe. Determine the colour of universal indicator when 10.0 cm³ of sodium hydroxide solution has been added to 25.0 cm³ of hydrochloric acid. Use Figure 10 and Figure 11.

The student used a pipette to measure 25.0 cm³ of hydrochloric acid. Figure 12 shows a pipette.

Calculate the percentage uncertainty in the volume measured using this pipette. Use the equation:

Give one advantage of using a pipette rather than using a measuring cylinder to measure the volume of hydrochloric acid.

This question is about structure and bonding.

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

Table 5 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 6 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 7 shows the student’s results.

Explain how the results demonstrate the law of conservation of mass. You should use data from Table 7 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.