4.5.2 Chemical cells and fuel cells

Question 1

What does OIL RIG stand for?

Answer 1

Oxidation
Is
Loss (of electrons)
Reduction
Is
Gain (of electrons)

Question 2

What are the most and least reactive metals in a cell?

Answer 2

The most is the anode (negative) as this is where oxidation occurs
The least is the cathode (positive) as this is where reduction occurs

Question 3

Describe the factors affecting the voltage.

Answer 3

• Identity of metals
• Reactivity difference (bigger diff = bigger voltage)
• Electrolyte: type, concentration

Question 4

Why does more voltage mean more reactive?

Answer 4

Since more voltage means more electrons, and since electrons are negatively charged, it is more reactive.

Question 5

Why do non-rechargeable cells stop producing electricity?

Answer 5

Reaction stops because all reactants have lost their electrons (reactant is used up)

Question 6

Why is sodium chloride solution conductive but not water?

Answer 6

Because sodium chloride, when molten, dislocates (separates) into charged ions that can flow freely.

Question 7

How do Hydrogen Fuel Cells conduct electricity?

Answer 7

They release electrons from H2 and release the energy from these delocalized electrons

Question 8

State the half reaction at the anode of an alkali hydrogen fuel cell.

Answer 8

H2 (g) + 2OH- (aq) > 2e- + 2H2O

Question 9

State the half reaction at the cathode of a alkali hydrogen fuel cell.

Answer 9

1/2O2 (g) + H2O (aq) + 2e- > 2OH- (aq)

Question 10

State the overall balanced equation for the reaction in a hydrogen fuel cell.

Answer 10

2H2 + O2 > 2H2O