Question

Balance the following equation:

$KCl{O}_3+H_{2}S{O}_4\to KHS{O}_4+HCl{O}_4+Cl{O}_2$

• A. $3KCl{O}_3+3H_{2}S{O}_4\to 3KHS{O}_4+HCl{O}_4+2Cl{O}_2+H_{2}O$
• B. $KCl{O}_3+5H_{2}S{O}_4\to 3KHS{O}_4+3HCl{O}_4+2Cl{O}_2+3H_{2}O$
• C. $3KCl{O}_3+4H_{2}S{O}_4\to 3KHS{O}_4+2HCl{O}_4+2Cl{O}_2+H_{2}O$
• D. None of these

Answer 1

The correct option is A $3KCl{O}_3+3H_{2}S{O}_4\to 3KHS{O}_4+HCl{O}_4+2Cl{O}_2+H_{2}O$

The unbalanced redox equation is as follows:
$KCl{O}_3+H_{2}S{O}_4\to KHS{O}_4+HCl{O}_4+Cl{O}_2$

Balance all atoms other than H and O.
$2KCl{O}_3+2H_{2}S{O}_4\to 2KHS{O}_4+HCl{O}_4+Cl{O}_2$

The oxidation number of Cl changes from +5 to +7. The change in the oxidation number of 1 Cr atom is 2.

The oxidation number of Cl changes from +5 to 4. The change in the oxidation number of Cl is 1.

The increase in the oxidation number is balanced with decrease in the oxidation number by multiplying $KCl{O}_3$ and $Cl{O}_2$ with 2. Balance K
$3KCl{O}_3+2H_{2}S{O}_4\to 2KHS{O}_4+HCl{O}_4+2Cl{O}_2$

O atoms are balanced by adding 1 water molecule on RHS.
$3KCl{O}_3+3H_{2}S{O}_4\to 3KHS{O}_4+HCl{O}_4+2Cl{O}_2+H_{2}O$

Hydrogen atoms are balanced.
$3KCl{O}_3+3H_{2}S{O}_4\to 3KHS{O}_4+HCl{O}_4+2Cl{O}_2+H_{2}O$

This is the balanced chemical equation.