Question

Classify the following as an acid or base according to Bronsted-Lowry concept:
i.) $C{{H}_{3}}CO{{O}^{-}}$
ii.) ${{H}_{3}}{{O}^{+}}$
iii.) $SO_{4}^{2-}$
iv.) $HCl$
A.) (i) - Bronsted base (ii) - Bronsted base (iii) - Bronsted base (iv) - Bronsted acid
B.) (i) - Bronsted acid (ii) - Bronsted acid (iii) - Bronsted acid (iv) - Bronsted base
C.) (i) - Bronsted base (ii) - Bronsted acid (iii) - Bronsted base (iv) - Bronsted acid
D.) (i) - Bronsted acid (ii) - Bronsted acid (iii) - Bronsted base (iv) - Bronsted base

Answer 1

Hint:As per Bronsted-Lowry concept an acid is the one that can donate hydrogen ions and base is the type of molecule that can accept hydrogen ions.
Correct option is C.

Complete answer:
Bronsted-Lowry gave a general definition of acids and bases.
A substance that has the ability to donate a hydrogen ion is known as acid.
A substance that has the ability to accept the hydrogen ion is known as base.
Therefore, acids are the ones which are the proton donors and the bases are the ones which are proton acceptors.
The acid base pairs that differ by only one proton are called conjugate acid-base pairs.
The first molecule $C{{H}_{3}}CO{{O}^{-}}$ is the Bronsted base as it has a tendency to accept hydrogen ion.
The second molecule is ${{H}_{3}}{{O}^{+}}$ the Bronsted acid as it is a proton donor as it has a tendency to give hydrogen ions.
The third molecule is $SO_{4}^{2-}$ the Bronsted base as it has a negative charge over it so it will accept hydrogen ions.
The fourth molecule is $HCl$ Bronsted base as it will hydrogen ions to form chloride ions.
Therefore, option C comes out to be true which states that:
(i) - Bronsted base (ii) - Bronsted acid (iii) - Bronsted base (iv) - Bronsted acid

Note: Bronsted-Lowry gave the general definitions of acid and bases which states that acid is the one which can donate hydrogen ions, ${{H}^{+}}$ and the base is the one that can accept hydrogen ions ${{H}^{+}}$. An acid and base are the conjugate pairs of each other.