Question

The complete balanced equation is:

$CuO+N{H}_3\to Cu+N_2+H_{2}O$

• A. $3CuO+2N{H}_3\to 3Cu+N_2+3H_{2}O$
• B. $CuO+2N{H}_3\to 3Cu+2N_2+3H_{2}O$
• C. $3CuO+N{H}_3\to 3Cu+N_2+3H_{2}O$
• D. None of these

Answer 1

The correct option is A $3CuO+2N{H}_3\to 3Cu+N_2+3H_{2}O$

The unbalanced redox equation is as follows:
$CuO+N{H}_3\to Cu+N_2+H_{2}O$
Balance all atoms other than H and O.
$CuO+2N{H}_3\to Cu+N_2+H_{2}O$
The oxidation number of Cu changes from 2 to 0. The change in the oxidation number of Cu is 2.
The oxidation number of N changes from -3 to 0. The change in the oxidation number of one atom of N is 3. For 2 N atoms, the total change is 6.
The increase in the oxidation number is balanced with decrease in the oxidation number by multiplying $CuO$ and $Cu$ with 3.
$3CuO+2N{H}_3\to 3Cu+N_2+H_{2}O$
O atoms are balanced by adding 2 water molecule on RHS.
$3CuO+2N{H}_3\to 3Cu+N_2+3H_{2}O$
H atoms are balanced.
This is the balanced chemical equation.