Question

How do you balance this redox reaction using the oxidation number method?$HN{O_3}\left( {aq} \right) + {H_3}As{O_3}\left( {aq} \right) \to NO\left( g \right) + {H_3}As{O_4}\left( {aq} \right) + {H_2}O\left( l \right)$

Answer 1

Here the given equation is in an unbalanced state consequently we need to balance it. Here we need to realize that there are two different ways to balance a redox reaction which is oxidation number technique and half equation method.

Complete step by step answer:
Selection of strategy is really our need yet here the inquiry is to balance utilizing oxidation number technique and balancing incorporates a progression of steps which can be followed to balance any skeletal equation. It incorporates sign of oxidation number, figuring increment or lessening in oxidation number, duplicating the equation to balance, and last balancing utilizing$H$and$O$particles.
Your unbalanced equation is
$HN{O_3} + {H_3}As{O_3} \to NO + {H_3}As{O_4} + {H_2}O$
-The oxidation numbers are:
Left hand side:$H = + 1$;$N = + 5$;$O = - 2$;$As = + 3$
Right hand side:$N = + 2$;$O = - 2$;$H = + 1$;$As = + 5$
-The changes in oxidation number are:
$N$:$+ 5 \to + 2$;$Change = - 3$
$As$:$+ 3 \to + 5$;$Change = + 2$
-You need$3$molecules of$As$for each$2$particle of$N$.
This gives you complete changes of$+ 6$and$- 6$.
-Supplement coefficients to get these numbers.
$2HN{O_3} + 3{H_3}As{O_3} \to 2NO + 3{H_3}As{O_4} + {H_2}O$
-Equilibrium$O$.
$2HN{O_3} + 3{H_3}As{O_3} \to 2NO + 3{H_3}As{O_4} + 1{H_2}O$
-Equilibrium$H$.
Done.
-Watch that all molecules balance.
Left hand side:$11H$;$2N$;$15O$;$3As$
Right hand side:$2N$;$15O$;$11H$;$3As$

The balanced equation is
$\boxed{2HN{O_3} + 3{H_3}As{O_3} \to 2NO + 3{H_3}As{O_4} + {H_2}O}$

Note: Actually, while balancing a redox reaction we need to remember that it is somewhat more confounded when contrasted with mass balancing. In this way, we ought to get it done with very focus during figuring like discovering oxidation number, investigating change in oxidation number, duplicating, embeddings coefficients and so forth Oxidation and decrease measure by and large in a substance reaction is really named as redox reaction.