Answer:
3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O
Explanation:
Cu + HNO3 → Cu(NO3)2 + NO + H2O
The first step is to write the oxidation numbers for each atoms in the given equation
Cu0 + H+1N+5O-23 → Cu+2(N+5O-23)2 + N+2O-2 + H+12O
Identify the oxidizing and reducing agent
OXIDATION --- Cu0 → Cu+2(N+5O-23)2 + 2e-
REDUCTION---H+1N+5O-23 + 3e- → N+2O
Balance equation in half reaction
Cu0 + 2HNO3 → Cu+2(N+5O-23)2 + 2e-
H+1N+5O-23 + 3e- → N+2O
Now balance the charge
Cu0 + 2HNO3 → Cu+2(N+5O-23)2 + 2e- + 2H+
H+1N+5O-23 + 3e- + 3H+ → N+2O
Balance the oxygen atom
Cu0 + 2HNO3 → Cu+2(N+5O-23)2 + 2e- + 2H+
H+1N+5O-23 + 3e- + 3H+ → N+2O-2 + 2H2O
Make electron gain equivalent to electron lost.
3Cu0 + 6HNO3 → 3Cu+2(N+5O-23)2 + 6e- + 6H+
2H+1N+5O-23 + 6e- + 6H+ → 2N+2O-2 + 4H2O
Complete reaction
3Cu0 + 8H+1N+5O-23 + 6e- + 6H+ → 3Cu+2(N+5O-23)2 + 2N+2O-2 + 6e- + 4H2O + 6H+
Simplify the equation
3Cu0 + 8H+1N+5O-23 → 3Cu+2(N+5O-23)2 + 2N+2O-2 + 4H2O
Final equation
3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O
