Explain why the voltage produced by a chemical cell depends on the type of chemicals used in the cell. In your answer, refer to what happens when the reactants in a non-rechargeable cell are used up.

A chemical cell contains two half‑cells that undergo redox reactions, creating a potential difference.
1. The voltage is determined by the standard electrode potentials of the two electrodes; different chemicals have different electrode potentials.
2. Therefore, a cell using a zinc–copper couple will give a different voltage to one using a silver–lead couple.
3. In a non‑rechargeable cell the reactions are not reversible; once the reactants are consumed the redox process cannot proceed in reverse.
4. When one reactant is used up the cell can no longer maintain a potential difference, so the voltage falls to zero.