Question

In one of the following reactions $\text{HN}{{\text{O}}_{\text{3}}}$ does not behave as an oxidizing agent. Identify it:

• A. ${{I}_{2}}+10HN{{O}_{3}}\xrightarrow{{}}2HI{{O}_{3}}+10N{{O}_{2}}+4{{H}_{2}}O$
• B. $3Cu+8HN{{O}_{3}}\xrightarrow{{}}3Cu{{(N{{O}_{3}})}_{2}}$ $+\,2NO+4{{H}_{2}}O$
• C. $4Zn+10HN{{O}_{3}}\xrightarrow{{}}4Zn{{(N{{O}_{3}})}_{2}}$ $+\,N{{H}_{4}}N{{O}_{3}}+3{{H}_{2}}O$
• D. $2HN{{O}_{3}}+{{P}_{2}}{{O}_{5}}\xrightarrow{{}}2HP{{O}_{3}}+{{N}_{2}}{{O}_{5}}$

Answer 1

Answer: (D)

$2HN{{O}_{3}}+{{P}_{2}}{{O}_{5}}\xrightarrow{{}}2HP{{O}_{3}}+{{N}_{2}}{{O}_{5}}$

Answer 2

[a] ${{\text{I}}_{\text{2}}}\text{+}\,\text{10}\overset{\text{+}\,\text{5}}{\mathop{\text{HN}}}\,{{\text{O}}_{\text{3}}}\xrightarrow{{}}$
$2HI{{O}_{3}}+10\overset{+2}{\mathop{NO}}\,\,+\,4{{H}_{2}}O$
In the reaction $\text{HN}{{\text{O}}_{\text{3}}}$
is acting as oxidizing agent because i|Ls oxidation state is decreasing from + 5 to + 2.
[b] $\text{3Cu}\,\text{+}\,\text{8}\overset{\text{+5}}{\mathop{\text{HN}}}\,{{\text{O}}_{\text{3}}}\xrightarrow{{}}$
$3Cu{{(N{{O}_{3}})}_{2}}+2\overset{+2}{\mathop{NO}}\,+4{{H}_{2}}O$
It is reaction in which $\text{HN}{{\text{O}}_{\text{3}}}$ is acting as oxidising agent because oxidation number of nitrogen is decreasing.
[c] $4Zn+10\overset{+5}{\mathop{HN}}\,{{O}_{3}}\xrightarrow{{}}4Zn{{(N{{O}_{3}})}_{2}}$
$+\,N{{H}_{4}}\,{{\overset{+2}{\mathop{NO}}\,}_{3}}\,+3{{H}_{2}}O$
$\therefore$ It is also a reaction, in which $\text{HN}{{\text{O}}_{\text{3}}}$ is oxidizing agent.
[d] $2HN{{O}_{3}}+{{P}_{2}}{{O}_{5}}\xrightarrow[{}]{{}}2HP{{O}_{3}}+{{N}_{2}}{{O}_{5}}$
${{P}_{2}}{{O}_{5}}$ dehydrating agent.
So in this reaction $\text{HN}{{\text{O}}_{\text{3}}}$ does not act as oxidizing agent.