Question

Is $HN{O_3}$ an acid or a base?

Answer 1

Hint : Any chemical compound can be classified as an acid or a base depending upon the acid-base theory used to describe its nature. Writing the dissociation reaction for the chemical compound in an aqueous medium and ions released would help in the classification.

Complete Step By Step Answer:
According to the Arrhenius Acid-base theory, any chemical compound that releases hydrogen ions (or protons) in aqueous solutions is called an acid and the one that releases hydroxide ions in aqueous solution is called a base.
The strength of an Arrhenius acid is determined by the amount of hydrogen ions ${H^ + }$ released and that of an Arrhenius base is determined by the amount of hydroxide ions $O{H^ - }$ released by it. The higher the amount of ${H^ + }$ ions released, lower will the pH and stronger will be the acid. The higher the amount of $O{H^ - }$ ions released, higher will be the pH and stronger will be the base.
$HN{O_3}$ is known as nitric acid and is a strong protic acid that releases one mole of protons (hydrogen ions) per mole of $HN{O_3}$ dissociated.
$HN{O_3}(aq) \to {H^ + } + N{O_3}^ -$
Apart from the fact that it is capable of releasing protons in solution, the reactions carried out with the help of $HN{O_3}$ can be used to classify it as an acid. Metals being slightly basic in nature, react with acids to give the corresponding salt with the evolution of hydrogen gas.
$HN{O_3}$ reacts with magnesium metal to give salt along with hydrogen gas.
$2HN{O_3} + Mg \to Mg{(N{O_3})_2} + {H_2} \uparrow$
Nitric acids also show a neutralization reaction with bases like sodium hydroxide.
$HN{O_3} + NaOH \to NaN{O_3} + {H_2}O$
Thus, $HN{O_3}$ is an acid.

Note :
All hydrogen containing compounds are not acids. The hydrogen present in the ionic compound should have a tendency to get dissociated from the molecule in the form of protons (or hydrogen ions) in aqueous solutions, only then the compound is called an Arrhenius acid.