Question

Phenol and benzoic acid can be distinguished by:
A. aqueous $NaHC{O_3}$
B. aqueous $NaN{O_3}$
C. aqueous $NaOH$
D. conc. ${H_2}SO4$

Answer 1

In this type of questions we have to choose the chemical such that the reaction is possible with one reactant as in the given question we should choose that chemical which can react with phenol or benzoic acid.

Complete step by step solution: We have phenol and benzoic acid which are too distinguished.
As we all know that phenol is a type of weak acid and weak acid can react with only a strong base.
$\therefore$we all know as by reaction rule $\to$
Weak acid cannot react with weak bases so we have to take strong bases for reaction with phenol.
Again we also know that aqueous $NaHC{O_3}$is a weak base so it cannot react with phenol.
Because weak acid and weak base can`t be react
${C_6}{H_5}OH + NaHC{O_3} \to$no reaction.
Now,
We have benzoic acid which is a strong acid and benzoic acid can react with weak bases
Because strong acid and weak bases can easily reacted
So as by below given reaction:
$PhCOOH + NaHC{O_3} \to PhCOONa + {H_2}O + C{O_2}$
We can say that benzoic acid will react with $NaHC{O_3}$

So option number A will be the correct answer.

Note: We should keep in mind that phenol is an alcohol having alcoholic functional group so it can't be a stronger acid than a compound which has an acidic functional group for example any carbonyl compound. That's why a compound with acid as its functional group is considered to be stronger acid than alcohol.