Question

The correct balanced equation of the following chemical reaction is :
$CuO+N{H}_3⟶Cu+H_{2}O+N_2$

• A. $3CuO+N{H}_3⟶3Cu+N_2+3H_{2}O$
• B. $CuO+2N{H}_3⟶Cu+N_2+H_{2}O$
• C. $3CuO+2N{H}_3⟶3Cu+N_2+3H_{2}O$
• D. $2CuO+2N{H}_3⟶2Cu+N_2+3H_{2}O$

Answer 1

The correct option is C $3CuO+2N{H}_3⟶3Cu+N_2+3H_{2}O$

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