Question

Which acid is the queen of acids?

Answer 1

It is one of the strong oxidizing acids, almost all the metals and non-metals soluble in this acid, it is used as an oxidizer in rocket fuel.

Complete answer:
$HN{{O}_{\begin{smallmatrix}
3 \\

\end{smallmatrix}}}$known as Nitric acid is a queen of acid because of highly reactivity in nature.$HN{{O}{3}}$in pure form is a colorless liquid. But on long standing it turns brown in colour due the formation$N{{O}{2}}$gas known as Nitrogen Dioxide.$4HN{{O}{3}}\xrightarrow[S\tan ding]{Long}2{{H}{2}}O+4N{{O}{2}}+{{O}{2}}$It is exclusively manufactured by the Ostwald process. In the process$N{{H}{3}}$(ammonia gas) is oxidized in the presence of$PtRh$(Platinum- Rhodium) catalyst and${{O}{2}}$from air leads in the formation of$NO$(Nitric oxide).$4N{{H}{3}}+5{{O}{2}}\xrightarrow{Pt-Rh}4NO+6{{H}{2}}O$$NO$formed combines with oxygen gas to form$N{{O}{2}}$.$2NO+{{O}{2}}\to 2N{{O}{2}}$$N{{O}{2}}$absorbed in water to form$HN{{O}{3}}$and$NO$,which is then recycled and again used in the manufacturing of nitric acid.$3N{{O}{2}}+{{H}{2}}O\to 2HN{{O}{3}}+NO$It reacts with all the metals. Depending of the concentration of nitric acid it forms metal nitrate and gases like$N{{O}{2}},{{N}{2}}O,{{H}{2}},NO$is formed. Like as follows:$Zn+4HN{{O}{3}}(conc)\to Zn{{(N{{O}{3}})}{2}}+2{{H}{2}}O+N{{O}{2}}$$\begin{aligned}
& 4Zn+10HN{{O}{3}}(dil)\to 4Zn{{(N{{O}{3}})}{2}}+5{{H}{2}}O+{{N}{2}}O \\
& Mg+2HN{{O}{3}}(V.dil)\to Mg{{(N{{O}{3}})}{2}}+{{H}{2}} \\
& 3Pb+8HN{{O}{3}}(dil)\to 3Pb{{(N{{O}{3}})}{2}}+2NO+4{{H}{2}}O \\
\end{aligned}$Similarly it reacts with non-metals are as follows$\begin{aligned}
& {{I}{2}}+10HN{{O}{3}}\to 2HI{{O}{3}}+4{{H}{2}}O+10N{{O}{2}} \\
& P+5HN{{O}{3}}\to {{H}{3}}P{{O}{4}}+{{H}{2}}O+5N{{O}{2}} \\
\end{aligned}$Elements like$Fe,Cr,Al$show resistance in reaction with$HN{{O}{3}}$as an oxide film of respective element is formed on the surface which is passive in nature. Noble metals like$Au,Pt$doesn’t show reaction with nitric acid. But combination in nitric acid and conc hydrochloric acid in$1:3$dissolves nobles metals in their chloride form.$\begin{aligned}
& HN{{O}{3}}+\underset{conc}{\mathop{3HCL}},\to 2{{H}{2}}O+2C{{l}^{-}}+\underset{\begin{smallmatrix}
Tildons \\
\operatorname{Re}agent
\end{smallmatrix}}{\mathop{NOCL}}, \\
& Au+3C{{l}^{-}}+HCL\to H[Auc{{l}{4}}] \\
& Pt+4C{{l}^{-}}+2HCL\to {{H}{2}}[PtC{{l}{6}}] \\
\end{aligned}$Combination of$HN{{O}_{3}}$and$concHCL$ is known as Aqua regia.

Note:
Brown Ring test is used for the detection of Nitrate $(NO_{3}^{-})$ ion is solution. In this $F{{e}^{2+}}$ (Ferrous ion) reduces nitrate to nitric acid and then $F{{e}^{2+}}$ reacts with nitric acid to form Brown ring complex (i.e$[Fe{{({{H}_{2}}O)}_{5}}NO]S{{O}_{4}}$ )