Question

The complete balanced equation is:

$I^{-}+H_2{O}_2\to H_{2}O+I_2$

• A. $H_2{O}_2+2I^{-}+2H^{+}\to 2H_{2}O+I_2$
• B. $H_2{O}_2+2I^{-}+2H^{+}\to 3H_{2}O+2I_2$
• C. $2H_2{O}_2+2I^{-}+2H^{+}\to 2H_{2}O+3I_2$
• D. none of these

Answer 1

The correct option is A $H_2{O}_2+2I^{-}+2H^{+}\to 2H_{2}O+I_2$

The unbalanced redox equation is as follows:
$I^{-}+H_2{O}_2\to H_{2}O+I_2$
Balance all atoms other than H and O.
$2I^{-}+H_2{O}_2\to H_{2}O+I_2$
The oxidation number of I changes from -1 to 0. The change in the oxidation number of I is 1.For 2 I atoms, the total change is 2.
The oxidation number ofO changes from -1 to -2. The change in the oxidation number of one atom of O is 1. For 2 O atoms, the total change is 2.
The increase in the oxidation number is balanced with decrease in the oxidation number.
O atoms are balanced by adding 1 water molecule on RHS.
$2I^{-}+H_2{O}_2\to 2H_{2}O+I_2$
H atoms are balanced by adding $2H^{+}$ on LHS.
$2I^{-}+H_2{O}_2+2H^{+}\to 2H_{2}O+I_2$
This is the balanced chemical equation.