Question

3 Cu(s) + 8 H + (aq) + 2 NO 3 – 1 (aq) → 3 Cu 2+(aq) + 2 NO(g) + 4 H 2O(l)

Answer 1

Cu and N atoms are balanced.

The oxidation number of Cu increases from 0 to +2. Total increase in the oxidation number is 2.

The oxidation number of N decreases from +5 to +4. Total decrease in oxidation number is 1.

Balance increase in oxidation number with decrease in oxidation number by multiplying the N species with 2.

Balance O atoms by adding one water molecule on RHS.

Balance H atoms by adding coefficient 4 to proton on LHS.

This is the balanced chemical equation. The coefficient for H + is 4.