Question

In the reaction,
$3CuO+2{NH}_3⟶N_2+3H_{2}O+3Cu$
the change of ${NH}_3$ to $N_2$ involves:

• A. Loss of 6 electrons per mole of $N_2$
• B. Loss of 3 electrons per mole of $N_2$
• C. Gain of 6 electrons per mole of $N_2$
• D. Gain of 3 electrons per mole of $N_2$

Answer 1

Answer: (A)

Loss of 6 electrons per mole of $N_2$

$3CuO+2{NH}_3⟶N_2+3H_{2}O+3Cu$

Oxidation state of N in $N{H}_3=-3$

Oxidation state of N in $N_2=0$

The change in oxidation state of $N$ is loss of $3$ electrons.

There are two atoms of nitrogen, hence the change involves loss of $6e^{-}$ for $1$ mol of $N_2$.