Chemical Cells & Fuel Cells (AQA GCSE Chemistry)

Exam Questions

2 hours22 questions
1a3 marks

Cells contain chemicals that react together, producing electricity.

Figure 1 shows a simple cell.

Figure 1

aqa-gcse-5-2e-tq1a-simple-cell

Label the apparatus used in the simple cell using the words from the box.

solute electrode voltmeter
ammeter            electrolyte                     electrolysis

1b2 marks

Give two factors that will affect the voltage that the cell produces.

1c1 mark

A student set up a simple cell as shown in Figure 1 using copper for both electrodes and sodium chloride solution as the electrolyte.

When the cell was set up, the voltmeter read 0 V.

What is the explanation for this reading?

Tick (✓) one box.

The circuit isn't complete  
The sodium chloride solution cannot conduct electricity  
The electrodes were made of the same metal  

1d2 marks

Cells can be connected together to form a battery.

Draw a ring around the most suitable answers to complete the sentences.

  A battery consists of two or more cells connected in

a circuit

parallel

series

  Three 1.5 V cells connected correctly would produce

1.5 V

4.5 V

3.4 V

 

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2a2 marks

Cells and batteries can be non-rechargeable and rechargeable.


Complete the sentences using the words in the box to explain why.

stops changes speeds up
             slows down                     reverses



In non-rechargeable cells and batteries, the reaction ____________________ when one of the reactants has been used up so no more electricity is produced.

In rechargeable cells and batteries, the reaction  ____________________ when an external electrical current is supplied to the cell or battery.

2b1 mark

Are alkaline batteries examples of non-rechargeable or rechargeable batteries?

2c2 marks

A student made a cell as shown in Figure 1.

Figure 1

electrolysis-cell

They investigated what happened to the voltage when they changed the type of electrode. Their results are shown in the table:

Electrode A Electrode B Voltage in V
Silver Iron 1.3
Silver Chromium 3.4
Silver Zinc 2.1
Silver Silver 0.0
Silver Tin 0.8


Silver is the least reactive metal.

Tick (✓) two conclusions that the student could make from these results.

The most reactive metal is tin  
The most reactive metal is chromium  
The least reactive metal is chromium  
Zinc is more reactive than tin  
Tin is more reactive than iron  

2d3 marks

What are the correct identities of the independent variable and control variables in the investigation in part c)?

Draw lines from each variable to the correct name of the variable in the investigation.

You may draw more than one line from each variable.

2R0pdL_J_simple-cell-variables

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3a1 mark

Hydrogen and oxygen react together to form water.

Complete the word equation for this reaction:

hydrogen   +   ____________________   →   water

3b2 marks

The reaction between hydrogen and oxygen is used in hydrogen fuel cells.

Draw a ring around the correct answer to complete the sentences about hydrogen fuel cells.

  Water is produced when hydrogen undergoes

reduction

oxidation

combustion

  This causes the fuel cell to produce a

temperature change

gas

potential difference

3c3 marks

Figure 1 shows a diagram of a hydrogen fuel cell.

Figure 1aqa-gcse-5-2e-tq3c-hydrogen-fuel-cell


Complete the table to show the functions each of the substances perform in a hydrogen fuel cell.

Choose words from the box below.

electrolyte electrode waste product
                source of oxygen                     fuel

Substance Function
Potassium hydroxide solution  
Hydrogen  
Water  

3d2 marks

Give two advantages of using hydrogen fuel cells compared with using rechargeable cells and batteries.

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4a1 mark

Figure 1 shows a fuel cell.

Figure 1

fuel-cell

Hydrogen can be used as the fuel.

Complete the balanced symbol equation for the reaction that occurs in a hydrogen fuel cell.

___ H2   +   O2   →   ___ H2O

4b1 mark

Figure 2 shows the reaction profile for the reaction of hydrogen and water in a hydrogen fuel cell.

Figure 2

reaction-profile-v-to-z

Which of the labels represents hydrogen and oxygen? 

Tick (✓) one box.

V  
W  
X  
Y  
Z  

4c1 mark

Which of the labels in Figure 2 represents water?

Tick (✓) one box.

V  
W  
X  
Y  
Z  
4d1 mark

The first vehicle powered by a hydrogen fuel cell was built in 1966 by General Motors. It could travel at up to 70 mph in 30 seconds.

Suggest an advantage of using a hydrogen fuel cell in a car.

4e1 mark

Currently, only a small number of cars are manufactured that use hydrogen fuel cells.

Suggest a disadvantage of using hydrogen fuel cells in cars.

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1 mark

Hydrogen fuel cells can be used to power trains.

Why could people refer to the hydrogen fuel cell trains as the 'new' steam trains?

  • The hydrogen used is extracted from fossil fuels

  • The hydrogen fuel cell trains are slower than diesel trains

  • The reaction produces water that can be released as steam

  • The reaction in the fuel cell is a combustion reaction

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1a4 marks

A student investigated the voltage produced by simple cells using the apparatus shown in Figure 1.

Figure 1

aqa-gcse-5-2e-tq1a-general-electrochem-single-cell-answer

Using different metals for the electrodes produced different voltages as shown in Table 1 below. 

Table 1

Electrode A Electrode B Voltage in V
Copper Copper 0.00
Copper Tin 0.48
Copper Zinc 1.10
Copper Iron 0.78
Copper Magnesium 2.71

List the metals in the table in order of reactivity.

Most reactive   ____________________ 

____________________

____________________

____________________

Least reactive         Copper                   

1b2 marks

Explain how you arrived at your answer to part a).

1c2 marks

Batteries consist of electrochemical cells.

Describe how a 9.0 V battery can be made from cells of voltage 1.5 V

1d4 marks

Non-rechargeable cells eventually stop producing electricity. 

Explain why and name a typical cell that is non-rechargeable.

1e1 mark

Complete the word equation for the reaction which occurs in a hydrogen fuel cell.

hydrogen  +  ___________________  ⟶  water

1f2 marks

Give two reasons why using a hydrogen fuel cell is seen as a clean source of energy using the equation in part e).

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21 mark

In an investigation to discover the reactivity series of some common metals, an electrochemical cell has two metal electrodes placed in an electrolyte solution.

Electrode A is copper.

Electrode B is changed to each different metal in turn and the voltage of the cell is measured. The results are shown below:

Metal of electrode B Voltage (V)
Copper 0.00
Cobalt +0.62
Tin +0.48
Nickel +0.59

Starting with the least reactive, place these metals in order of ascending reactivity.

  • Cobalt, nickel, tin, copper

  • Copper, tin, nickel, cobalt

  • Tin, nickel, cobalt, copper

  • Copper, cobalt, nickel, tin

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31 mark

One of the electrodes used in an electrochemical cell is a 'hydrogen electrode'.

Four different metals were used in turn as the second electrode to complete the cell. The voltage of each cell was measured and is shown below:

Metal used on the second electrode Voltage of the cell compared to hydrogen (V)
Copper +0.34
Silver +0.80
Iron -0.04
Nickel -0.26

Which pair of metals would give the greatest voltage when used as electrodes in a different cell?

  • Nickel and silver

  • Iron and silver

  • Copper and silver

  • Copper and nickel

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4a1 mark

Some new models of cars are powered by hydrogen fuel cells.

What type of energy is released by these cells?

4b5 marks

Owners of these cars must buy hydrogen from specially equipped hydrogen filling stations. 

The number of these stations in the UK is expected to increase up to the year 2035 as can be seen in Figure 3.

Figure 3

5-2-chemical-cells--fuel-cells-medium-q4b

Explain why the UK government should encourage the production of more hydrogen filling stations. 

Use the data in Figure 3 and your own knowledge to answer this question, making reference to the reaction of hydrogen fuel cells.

4c2 marks

Give two disadvantages of using hydrogen fuel cells.

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1 mark

In some types of cell the chemical reaction can be reversed by applying an external current.

Which type of cell can this occur in?

  • Alkaline batteries

  • Rechargeable batteries

  • Fuel cells

  • All of the above

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61 mark

Hydrogen fuel cells are often used instead of rechargeable batteries in spacecraft.

Which of the following is not an advantage of using hydrogen fuel cells in spacecraft?

  • Water is the only product made in the reaction

  • The fuel cells have no moving parts so are easy to maintain

  • Hydrogen and oxygen are easily made by electrolysis of water

  • Hydrogen fuel cells are cheap

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7a4 marks

Electrochemical cells contain chemicals which react together.   

This reaction involves the movement of electrons which is what produces electricity.

Rechargeable cells are cells that can be recharged. 

Explain how this process occurs.

7b3 marks

Give three factors that affect the voltage produced by a cell.

7c1 mark

Balance the half-equation for the reaction which occurs at an electrode in one kind of hydrogen fuel cell.

H2   +  OH  ⟶  H2O   +  e

7d2 marks

Explain why the fuel cell in part (c) can be described as an alkaline fuel cell?

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8a1 mark

Some chemical reactions can produce electricity. 

Figure 1 shows a simple cell.

Figure 1

aqa-gcse-5-2e-tq1a-general-electrochem-single-cell-answer

Which of the combinations of Electrode A, Electrode B and Electrolyte from the table would not give a zero reading on the voltmeter in Figure 1?
 
Electrode A Electrode B Electrolyte Tick (one box.
Zinc Zinc Sodium chloride solution  
Iron Iron Water  
Copper  Zinc Sodium chloride solution  
Zinc  Copper Water  

 

8b1 mark

Alkaline batteries are non-rechargeable.

Explain why they cannot be recharged.

8c3 marks

Rechargeable lithium-ion batteries and hydrogen fuel cells can be used to power electric cars.

Complete the balanced equation for the overall reaction in a hydrogen fuel cell and state what type of reaction it is.

________ H2 + ________ ⟶ ________ H2O

8d6 marks

Table 2 below shows data based on different methods of powering electric cars.

Table 2

  Hydrogen fuel cell Rechargeable lithium-ion battery
Time to refuel or recharge in minutes 4 30
Distance car can travel per unit of energy in km 25 68
Distance car can travel before refuelling or recharging in miles Up to 420 Up to 230

Minimum cost of car in £

55,000 16,000
Cost of refuelling or recharging in £ 60 5

Use the table and your knowledge to evaluate the use of hydrogen fuel cells compared with rechargeable lithium-ion batteries to power electric cars.

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1a4 marks

In a hydrogen fuel cell, the reaction between hydrogen and oxygen produces electrical energy. The equation for the reaction is:

2H2   +   O2   →   2H2O

Hydrogen fuel cells can be used to power some cars.

Reactions happen at both the positive electrode and the negative electrode in the fuel cell.

Write the two half equations that occur at each electrode and state with reason what kind of reaction each one is.

1b
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5 marks

The energy required for a car powered by a hydrogen fuel cell to travel 400 km is 232 MJ.

The energy that is 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, in dm3, at room temperature and pressure needed for the car to travel 250 km.

1c1 mark

The volume of hydrogen gas that would be required to allow a car to travel a reasonable distance between refuelling would be greater than the volume of a tank that could fit in a car.

Suggest one way in which this volume can be decreased.

1d4 marks

Methanol can be used as the fuel in a fuel cell instead of hydrogen.

The chemical equation for is:

2CH3OH + 3O2 → 2CO2 + 4H2O


The equation for the reaction can be also be shown as:

combustion-of-methanol

Table 1 shows the bond energies of different bonds.

Table 1

Bond Bond energy in kJ/mol
C-H 412
O-H 464
C=O 805
C-O 360

The overall energy change for the reaction is -1318 kJ/mol.

Use the bond energies in Table 1 and the overall energy change to calculate the bond energy of the O=O bond in kJ/mol. 

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2a2 marks

A student investigated how the metal used as the electrode in a simple cell affected the voltage produced. They used the apparatus shown in Figure 1.

Figure 1

aqa-gcse-5-2h-tq2a-simple-cell-copper-electrode

The student's results are shown in Table 1.

Table 1

Metal used as Metal 2 Voltage produced in volts
Chromium 1.2
Iron 0.5
Magnesium 1.8
Nickel 1.0
Silver -0.6
Zinc 0.3

Which metal is the most reactive?

Explain your answer.

2b1 mark

Why does silver have a negative voltage?

2c2 marks

The half equation for the reaction that happens at the copper electrode in the simple cell made using copper and magnesium electrodes is:

Cu2+ + 2e- → Cu

Give the half equation for the reaction that occurs at the magnesium electrode and state whether this is oxidation or reduction, giving a reason why.

2d
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1 mark

Predict the voltage that would be produced if the simple cell was made with zinc and nickel electrodes.

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3a2 marks

A simple cell consists of two different metals in contact with an electrolyte.

Explain what a battery is.

3b2 marks

Batteries can be non-rechargeable and rechargeable.

Explain the difference between the two different types of batteries. 

3c2 marks

A student  made a battery from lemons as shown in Figure 1.

Figure 1

aqa-gcse-5-2h-tq3c-lemon-battery

The student found that if they had less than four lemon halves connected as shown in Figure 1, the bulb did not turn on.

Explain why.

3d2 marks

The student changed the bulb for a voltmeter so that they could measure the voltage produced.

They investigated what happened to the voltage produced by the battery when different metals were used instead of copper and zinc.

Give two control variables in this investigation.

3e2 marks

The results that the student obtained are shown in Table 1.

Table 1

vqeUDoEp_lemon-battery-results

The results give a positive voltage when metal 1 is more reactive than metal 2.

The results give a negative voltage when metal 2 is more reactive than metal 1.

List the metal in order of reactivity, starting with the least reactive metal.

3f
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3 marks

Predict the voltage that would have been obtained for the reading that was not taken where metal 1 is iron and metal 2 is aluminium.

Explain your answer.

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4a3 marks

Hydrogen fuel cells can be constructed using either an acidic or alkaline electrolyte.

The half equations at the electrodes in acidic conditions are:

  • H2 ⟶ 2 H+ + 2 e-
  • O2 + 4 H+ + 4 e- ⟶ 2 H2O

The half equations at the electrodes in alkaline conditions are:

  • H2 + 2 OH- ⟶ 2 H2O + 2 e-
  • O2 + 2 H2O + 4 e- ⟶ 4 OH-

The overall equation for the reaction in alkaline conditions is:

  • 2H2 + O2 → 2H2O

Suggest why the voltage produced in a hydrogen fuel cell with an acidic electrolyte is exactly the same as one with an alkaline electrolyte.

You should refer to the overall equation for the reactions in your answer.

4b2 marks

The electrodes used in hydrogen fuel cells can be made by using a porous ceramic material which has been coated in platinum.

Suggest two reasons why this method of making electrodes is preferential to using platinum rods as electrodes.

4c1 mark

The only product formed in hydrogen fuel cells is water so they are often thought of as sustainable.

Suggest a reason why this is not necessarily true.

4d2 marks

Other than any factors which may make fuel cells less sustainable, give two disadvantages of using hydrogen fuel cells compared with rechargeable battery, such as a lithium-ion battery, when used to power an electric car?

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