Question

You are given the reaction Cu + HNO3 Cu(NO3)2 + NO + H2O complete the final balanced equation based on half-reactions

Answer 1

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