Student reacts with a piece of copper with a silver nitrate solution in a single replacement reaction. Write and balance the equation for this reaction.

Cu(s) + 2AgNO₃(aq) → 2Ag(s) + Cu(NO₃)₂ (aq)

Explanation:

Reactants: Cu(s), AgNO₃(aq)

This is a redox reaction, where the Ag and the Cu change the oxidation state

Ag, from +1 to 0  →  reduction

Cu, from 0 to +2 →  oxidation

Ag⁺ + 1e⁻ → Ag      Reduction gains an electron

Cu → Cu²⁺ + 2e⁻    Oxidation releases 2 electrons

We multiply the half reactions:

(Ag⁺ + 1e⁻ → Ag) . 2   = 2Ag⁺ + 2e⁻ → 2Ag

(Cu → Cu²⁺ + 2e⁻) . 1  = Cu → Cu²⁺ + 2e⁻

We sum both reaction, so we cancel the e⁻:

2Ag⁺ + 2e⁻ + Cu → 2Ag + Cu²⁺ + 2e⁻

We add the other ions, to get the balanced equation:

Cu(s) + 2AgNO₃(aq) → 2Ag(s) + Cu(NO₃)₂ (aq)