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)