Chemical Cells + Fuel Cells

What is a cell?

A cell is composed of two electrodes dipped in an electrolyte solution. It produces electricity from a chemical reaction

What is a battery?

A battery consists of two or more cells connected in series

What determines the voltage obtained from a cell?

Identities of metals used as electrodes and the identity and concentration of an electrolyte

State the advantages of using cells and batteries

More or less cheap, some are rechargeable, a convenient source of electrical energy.

State the disadvantages of using cells and batteries

Harmful chemicals

Describe rechargeable cells

The chemical reactions are reversed when an external current is supplied.

Describe non-rechargeable cells

The reactants are used up, cannot be recharged

What is a fuel cell?

Fuel cells are supplied by fuel and oxygen to oxidise the fuel to generate electricity

What is the overall reaction in a hydrogen fuel cell?

2 H₂ + O₂ ⟶ 2 H₂O

What are the half equations in a hydrogen fuel cell?

Cathode: 2H₂ ⟶ 4H⁺ + 4e⁻

Anode: O₂ + 4H⁺ + 4e⁻ ⟶ 2H₂O

What are the advantages of hydrogen fuel cells?

No pollutants, no recharging.

What are the disadvantages of hydrogen fuel cells?

Flammable, H₂ difficult to store, fossil fuel production, toxic chemicals, expensive production of H₂ by electrolysis