Question

In the equation, $NaOH+HN{{O}_{3}}\to NaN{{O}_{3}}+{{H}_{2}}O$ nitric acid is acting as _______.
(A) oxidizing agent
(B) an acid
(C) a nitrating agent
(D) a dehydrating agent

Answer 1

Hint: Start by writing the reaction and write the names of each of the reactants and products in the reaction. Then label them as acid or base or conjugate acid or conjugate base or salt on both reactant and product sides. Take a look at the options and write their definitions. Then choose the correct option which describes nitric acid.

Complete step by step solution:
- The reaction given is, $NaOH+HN{{O}_{3}}\to NaN{{O}_{3}}+{{H}_{2}}O$
- According to the given equation, sodium hydroxide reacts with nitric acid to form sodium nitrate salt and water. This is an example of a neutralization reaction.
- Sodium hydroxide is a strong base and nitric acid is a strong acid.
- Strong acid reacts with a strong base to form salt and water.
- Now, let’s take a look at the options.
- Oxidizing agent is the species which oxidizes, that is, removes hydrogen atoms or removes electrons or adds oxygen atoms, to another reacting species thereby getting reduced itself. In the given reaction, the oxidation state of ions is not changing at all and is constant throughout the reaction, therefore, this option is eliminated.
- An acid is a compound which can either donate protons or accept electrons. In this case, nitric acid is acting as an acid and so, this option is correct.
- A nitrating agent is a reagent which when added to a compound gives nitrate derivative of that compound. Basically, the nitrating agent adds the nitrate group to the reactant. Here sodium hydroxide is getting nitrated as sodium hydroxide is converted to sodium nitrate.
- A dehydrating agent is a regent which has the tendency to dehydrate water molecules during the reaction. In this reaction, the water molecule is removed but it is due to neutralization reaction and not due to dehydrating property of nitric acid. Therefore, this option can also be eliminated.
- Therefore, nitric acid acts as an acid and a nitrating agent.

- Therefore, the correct answer is option B and C.

Note: Nitric acid acts as an acid, a nitrating agent, only in the presence of sulphuric acid in case of organic compounds, and a dehydrating agent. Organic compounds will undergo nitration only in the presence of nitrating mixture, nitric acid and sulphuric acid.