Give the preparation of Nitric acid $(HNO_3)$. Discuss its physical and chemical properties and state its uses.

(D) **Preparation**:
$1.$ Laboratory Method: Heating $NaNO_3$ or $KNO_3$ with concentrated $H_2SO_4$ in a glass retort.
$NaNO_3 + H_2SO_4 \rightarrow NaHSO_4 + HNO_3$
$2.$ Ostwald's Process:
$(i)$ $4NH_{3(g)} + 5O_{2(g)} \xrightarrow{Pt/Rh, 500 K, 9 bar} 4NO_{(g)} + 6H_2O_{(g)}$
(ii) $2NO_{(g)} + O_{2(g)} \rightleftharpoons 2NO_{2(g)}$
(iii) $3NO_{2(g)} + H_2O_{(l)} \rightarrow 2HNO_{3(aq)} + NO_{(g)}$
**Physical Properties**: It is a colorless liquid with a pungent odor. Freezing point is $231.4 K$ and boiling point is $355.6 K$. Laboratory grade nitric acid contains $68\%$ of $HNO_3$ by mass and has a specific gravity of $1.504$.
**Chemical Properties**:
$1.$ Acidic Nature: In aqueous solution,it behaves as a strong acid.
$HNO_{3(aq)} + H_2O_{(l)} \rightarrow H_3O^{+}_{(aq)} + NO_3^-(aq)$
$2.$ Oxidizing Nature: It is a strong oxidizing agent and attacks most metals except noble metals like $Au$ and $Pt$.
$3Cu + 8HNO_3(dilute) \rightarrow 3Cu(NO_3)_2 + 2NO + 4H_2O$
$Cu + 4HNO_3(concentrated) \rightarrow Cu(NO_3)_2 + 2NO_2 + 2H_2O$
It also oxidizes non-metals:
$I_2 + 10HNO_3 \rightarrow 2HIO_3 + 10NO_2 + 4H_2O$
$C + 4HNO_3 \rightarrow CO_2 + 2H_2O + 4NO_2$
**Uses**:
$1.$ In the manufacture of ammonium nitrate $(NH_4NO_3)$ for fertilizers.
$2.$ In the preparation of explosives like $TNT$ and nitroglycerine.
$3.$ For pickling of stainless steel and etching of metals.
$4.$ As an oxidizer in rocket fuels.