Power Cells
How chemistry makes electricity: simple cells that give a voltage from two metals in an electrolyte, batteries as joined cells, rechargeable and non-rechargeable cells, and the hydrogen fuel cell whose only waste is water.
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Making electricity from chemistry
A chemical reaction can push a current round a circuit, and that is how every battery works. This module works through simple cells, batteries, the difference between cells you recharge and cells you throw away, and the hydrogen fuel cell that keeps going as long as it is fed. Take care not to mix this up with electrolysis, which uses electricity rather than making it.
Cell words to know
Learn these before you wire anything up.
Rechargeable battery against fuel cell
Two ways to keep a device powered, with different trade-offs.
Know the families, weigh the fuel cell
In the exam, know the two families and be ready to weigh them up. A simple cell puts two different metals in an electrolyte to generate power, and linking several cells gives a battery; some kinds can be topped up again and some are used once. The hydrogen kind keeps going as long as it is fed, and its exhaust is clean, but the fuel behind it is awkward to store and to produce. For that comparison, give an advantage, a disadvantage and a conclusion.
Match the term
- cell
- battery
- rechargeable cell
- fuel cell
- chemicals reacting to make a voltage
- two or more cells joined
- a cell that can be used again
- produces power from a fuel and oxygen
Match the fact
- a hydrogen fuel cell
- a non-rechargeable cell
- a rechargeable cell
- storing the hydrogen
- gives off only water
- is thrown away when it runs down
- is charged again from the mains
- is a drawback of fuel cells
What comes out of a fuel cell?
What is the only waste product of a hydrogen fuel cell?
- Water
- Carbon dioxide
- Smoke
- Nothing at all
True about cells
Select the TWO true statements about cells and fuel cells.
- A battery is two or more cells joined together
- A hydrogen fuel cell needs no recharging while fuel is supplied
- A non-rechargeable cell can be charged again
- A hydrogen fuel cell produces carbon dioxide as its waste
Add up the voltage
A single cell produces 2 volts. A battery joins 4 such cells in a row, and their voltages add together. Multiply 2 by 4 to find the total voltage of the battery in volts. What is the answer?
Order how a fuel cell works
Put the steps of a hydrogen fuel cell in order, earliest first.
- Hydrogen is supplied to the fuel cell
- It reacts with oxygen inside the cell
- The reaction produces a voltage
- The only waste product is water
Complete the rules
A device where a chemical reaction produces a voltage is a _____. Two or more cells joined together make a _____. A cell that can be charged and used again is _____. A hydrogen fuel cell runs on hydrogen and oxygen and gives off only _____.
Spot the fuel-cell advantages
Tap the TWO advantages of a hydrogen fuel cell.
- its only waste product is water
- it never needs recharging while fuelled
- the hydrogen is hard to store safely
- it produces clouds of smoke
Pick the answer
Read each case and choose the best answer.
- A device joins several cells together to give a bigger voltage. What is it?
- A car runs on hydrogen and its exhaust is only water. What kind of cell powers it?
- Which of these is a disadvantage of hydrogen fuel cells?
Explain cells and fuel cells
Explain how chemical cells and hydrogen fuel cells work, and weigh up the fuel cell.
- Explain what a cell and a battery are, and rechargeable against non-rechargeable
- Explain how a hydrogen fuel cell produces a voltage
- Give one advantage and one disadvantage of a hydrogen fuel cell