Define Bronsted-Lowry base and explain with an example that water is a Bronsted-Lowry base.

  1. No.3. Define Bronsted-Lowry base and explain with an example that water is a Bronsted-Lowry base.

Answer. According to Bronsted-Lowry concept, a base is a substance that can accept a proton (H+) from another substance.

For example, when HC1 dissolves in water; HC1 acts as an acid and H2O as a base because it takes proton from HC1.

HCl(aq) + H2O(aq)   —————>   H3O+  (aq) + Cl- (aq)

Acid  Bas  Conjugate acid Conjugate bas

  1. No. 4.How can you justify that Bronsted-Lowry concept of acid arid base is applicable to non-aqueous solutions?

Answer. Arrhenius concept of acids and bases was having limitations of applicable only in aqueous medium. But Bronsted Lowry concept has broader scope. It is applicable to non-aqueous solutions. According to this concept:

An acid is a substance (molecule or ion) that can donate a proton (H+) to another substance.

A base is a substance that can accept a proton (H+) from another substance.

This concept does not require an aqueous medium for an acid or a base to ionize. This concept requires only two substances; one act as an acid and the other acts as a base. It means an acid and a base always work together to transfer a proton. For example, a reaction between HC1 and NH3 takes place as follows

HCl(aq) + NH3(aq)         NH4+(aq) + Cl-(aq)

  1. No. 5.Which kind of a bond forms between a Lewis acid and a base?

Answer. Lewis acid is an electron pair acceptor and Lewis base is an electron pair donor. A coordinate bond is formed when one atom donates a pair of electrons and the other atom accepts a pair of electrons. Hence as Lewis base donates a pair of electrons and Lewis acid accept the pair of electrons, there forms a coordinate covalent bond between Lewis acid and base. For example, formation of coordinate covalent bond between Lewis acid BF3 and Lewis, base NH3.

BF3 + NH3 ——— > F3B   NH3

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