Question

Which of the following is a Brønsted-Lowry acid-base reaction?

	CH3CH2NH2(aq)+C6H5COOH(aq)⇄CH3CH2NH3+(aq)+C6H5COO-(aq)
	H2O(l)+CO2(aq)⇄HCO3-(aq)+H+(aq)
	Fe3+(aq)+H2O(l)⇄FeOH2+(aq)+H+(aq)
	HCl(aq)+Zn(s)⇄ZnCl2(aq)+H2(g)

Answer 1

Ans: According to the Bronsted-Lawry acid-base concept: An acid is a substance that loses a proton and the base is a substance that gains a proton.

In the given reaction:

1: CH₃CH₂NH₂(aq)+C₆H₅COOH(aq)⇄CH₃CH₂NH₃⁺(aq)+C₆H₅COO^-(aq)

In this reaction, CH₃CH₂NH₂(aq) gains a proton and becomes CH₃CH₂NH₃⁺(aq) and C₆H₅COOH(aq) loses a proton and becomes C₆H₅COO^-(aq). This means one species gains a proton and other species lose a proton. Hence, this reaction is a Bronsted-Lawry acid-base reaction.

2: H₂O(l)+CO₂(aq)⇄HCO₃^-(aq)+H⁺(aq)

H₂O(l)+CO₂(aq) gives H₂CO₃ (aq) which loses one proton to give HCO₃^-(aq). As there are no species to gain proton hence this is not a Bronsted-Lawry acid-base reaction.

3: Fe³⁺(aq)+H₂O(l)⇄FeOH²⁺(aq)+H⁺(aq)

No species is present to gain the proton lost from H₂O. Hence, it is not a Bronsted-Lawry acid-base reaction.

4: HCl(aq)+Zn(s)⇄ZnCl₂(aq)+H₂(g)

The above reaction is a redox reaction as there is an exchange of electrons between the species and no exchange of protons. Hence, this reaction is not a Bronsted-Lawry acid-base reaction.