Chemical Cells & Fuel Cells (Edexcel GCSE Chemistry)

Hydrogen fuel cells can be used to power trains.

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

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?

Hydrogen and oxygen are reactants in some fuel cells.

Which word equation shows the overall reaction that occurs in these fuel cells?

A torch contains a chemical cell.

The torch is turned on and then left on for many hours.

Describe what you would happen when the torch is turned on and then left for many hours.

A chemical cell can be made by placing two metals into an electrolyte.

Figure 3 shows how the voltage of a simple chemical cell can be measured.

Figure 3

A student investigated how the voltage of this cell was affected by the metal used for the rods.

Which is the only variable that should be changed in the investigation?

(2)

Hydrogen fuel cells can be used in lorries and cars.

Which of the following is a potential disadvantage of using hydrogen fuel cells instead of petrol in a car?

Hydrogen can be used in a hydrogen-oxygen fuel cell. 

What does this cell produce?

Some batteries are examples of non rechargeable cells. 

Why do these batteries eventually go flat?

Higher Only 

Methane reacts with steam to form hydrogen and carbon dioxide.

The reaction takes place in two stages.

stage 1: CH₄ (g) + H₂O (g) 3H₂ (g) + CO (g)
stage 2: CO (g) + H₂O (g) H₂ (g) + CO₂ (g)

Hydrogen-oxygen fuel cells can be used to provide electrical energy in a spacecraft.

The reaction that takes place in the fuel cell is

hydrogen + oxygen → water

Evaluate the advantages and disadvantages of providing electrical energy in a spacecraft using hydrogen-oxygen fuel cells rather than chemical cells.

A fuel cell produces electrical energy by the oxidation of a fuel by oxygen.
The fuel is usually hydrogen but methane and methanol are two other fuels which may be used.
A diagram of a hydrogen fuel cell is given below in Figure 1.

Figure 1

When the fuel is hydrogen, the hydrogen is oxidised to form water, which is the only product.

Suggest what additional product would be formed if methane was used.

Write the chemical equation for the chemical reaction that takes place in a hydrogen fuel cell.

Higher Only

In a hydrogen fuel cell, hydrogen loses electrons at the anode.

Write the half equation to show the reaction at the anode.

Higher Only

Hydrogen and oxygen can also react in a combustion reaction forming water vapour.

Calculate the mass of water vapour produced when 500 cm³ of hydrogen combusts in excess oxygen.

Mass of water vapour ...................................... (g)

Electrolysis and chemical cells involve both electricity and chemical reactions. 

Explain the difference between the processes in a chemical cell and electrolysis. 

Higher Only

In a hydrogen-oxygen fuel cell, hydrogen is oxidised at the anode. 

Write the half-equation for this reaction. 

Hydrogen is used an alternative to petrol as a fuel in car engines. 

Evaluate the advantages and disadvantages of using hydrogen rather than petrol as a fuel for cars.