SC16

Question 1

What components does a simple chemical cell have?

Answer 1

1. 2 different metals, each dipped into a solution of one of their salts
2. A ‘salt bridge’ to allow dissolved ions to pass from one solution to the other

Question 2

How does a chemical cell work?

Answer 2

A voltage is produced between the 2 metals used in the chemical cell (the further apart the 2 metals are in the reactivity series, the greater the voltage). The chemical cells then store their reactants and when one of them is used up, the reaction stops and a voltage is no longer produced (battery goes ‘flat’).

Question 3

How does a fuel cell produce electricity?

Answer 3

It needs to be continuously supplied with both a fuel and oxygen from outside, which will react together and produce electricity.

Question 4

What is different about hydrogen being used as a fuel?

Answer 4

The fuel cell generates electricity and water.

Question 5

What are the advantages of a hydrogen-oxygen fuel cell?

Answer 5

1. Much quieter
2. Need less maintenance than a petrol or diesel engine
3. Do not produce carbon dioxide (greenhouse gas, contributes to global warming)

Question 6

What are the differences between fuel cells and chemical cells (batteries)?

Answer 6

1. In fuel cells voltage (potential difference) stays the same while the fuel cell is working; the voltage in chemical cells gradually decreases over time with use as the chemicals are being used up
2. Fuel cells have large reserves of fuel so they last a long time; chemical cells have small reserves of chemicals so they need to be recharged or disposed of
3. Fuel cells cannot be recharged; some types of chemical cells are rechargeable but many are disposable
4. Fuel cells are expensive to make; chemical cells are cheap to make

Question 7

What is a hydrogen-oxygen fuel cell made up of?

Answer 7

Check chemistry book page 125 diagram.