Question

Write and balance the half-reaction for the reduction of nitrate, NO3 (aq), to nitrogen gas, N2(g), in a basic solution. Use e to represent the formula of an electron. Do NOT include the state (phase) information. Do NOT write out coefficients that are equal to Be sure to denote any charges as needed.

Answer 1

2NO−3 + 6H2O + 10e− ⟶ N2 + 12OH−

Step-by-step explanation:

First, write the half-reaction with the given reactant and product, balancing N atoms.

2NO−3 ⟶ N2

Next, add water to the half-reaction as needed to balance the number of oxygen atoms.

2NO−3 ⟶ N2 + 6H2O

Add H+ ions to balance the H atoms.

2NO−3 + 12H+ ⟶ N2 + 6H2O

Since the half-reaction is occurring in a basic solution, add 12OH− to each side of the equation to eliminate the H+ ions.

2NO−3 + 12H+ + 12OH− ⟶ N2 + 6H2O + 12OH−

Combine the H+ and OH− ions to form H2O, and cancel the H2O that appears on both sides of the equation.

2NO−3 + 6H2O ⟶ N2 + 12OH−

Complete the half-reaction by adding electrons to balance the charges.

2NO−3 + 6H2O + 10e− ⟶ N2 + 12OH−