Question

Balance the following equation.

$HN{O}_3+HBr\to NO+B{r}_2+H_{2}O$

• A. $2HN{O}_3+6HBr\to 2NO+3B{r}_2+4H_{2}O$
• B. $2HN{O}_3+3HBr\to 2NO+3B{r}_2+4H_{2}O$
• C. $2HN{O}_3+4HBr\to 2NO+5B{r}_2+4H_{2}O$
• D. None of these

Answer 1

The correct option is A $2HN{O}_3+6HBr\to 2NO+3B{r}_2+4H_{2}O$

The unbalanced redox equation is as follows:

$HN{O}_3+HBr\to NO+B{r}_2+H_{2}O$

Balance all atoms other than H and O.

$HN{O}_3+2HBr\to NO+B{r}_2+H_{2}O$

The oxidation number of bromine changes from -1 to 0. The change in the oxidation number of one bromine atom is 1. Total change in the oxidation number for 2 bromine atoms is 2.
The oxidation number of nitrogen changes from +5 to +2. The change in the oxidation number of nitrogen is 3.

The increase in the oxidation number is balanced with decrease in the oxidation number by multiplying
$HBr$ and $B{r}_2$ with 3 and by multiplying $HN{O}_3$ and $NO$ with 2.

$2HN{O}_3+6HBr\to 2NO+3B{r}_2+H_{2}O$

O atoms are balanced by adding 3 water molecules on RHS.

$2HN{O}_3+6HBr\to 2NO+3B{r}_2+4H_{2}O$

Hydrogen atoms are balanced.
Hence, this is the balanced chemical equation.