Bronsted-Lowry Concept as Acid and Base

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Bronsted-Lowry Concept as Acid and Base

Published by: Nuru

Published date: 26 Jun 2021

Bronsted-Lowry Concept as Acid and Base in Grade 12

Brosted-Lowry Concept as Acid and Base

Brosted-Lowry Concept as Acid and Base- The compound which can donate protons or proton donors are called acids.

According to this concept, the compound which can donate protons or proton donors are called acids. Similarly, the compound which can accept the proton or proton-acceptors is called bases.

HCL + H2O \rightleftharpoons CL– + H3­O+

In this reaction, HCL acts as an acid because it donates 1 proton while H2O acts as a base because it accepts 1 proton.

According to this concept NH4+, HSo4–, HCO3– etc act as acids because all of them can produce proton.

NH4+ + CH3COO–  \rightleftharpoons NH3 + CH3COOH

(acetate ion)                    (ammonia) (acetic acid)

Conjugate pair- A pair in which one form (i.e. acid or base) is formed from the another either by donating the proton or by accepting the proton is called conjugate pair.

Let us consider the following chemical reaction.

HCL + H2O \rightleftharpoons CL– + H3­O+  

The base which is produced when an acid donates proton is called conjugate base of the acid. Similarly, the acid which is produced when a base accepts proton is called conjugate acid of base. In the above reaction CL– is the conjugate acid of base.

Advantage of Bronsted-Lowey concept of acid and base

  1. Since the solvent is not mentioned so, this concept can be extended to both aquose as well as non-aquose solvents.
  2. Acid and base combine to give another acid and base.

For example:- HCL + H2O \rightleftharpoons CL– + H3­O+  

(Acid-1)   (base-1)            (conjugate base-2) acid-2

  1. Acid and bases can be ions as well as molecular substances
  2. Some species can act as acids or bases depending on what the other reactant is.

Limitations of Bronsted-Lowry concept of acid and base

  1. This concept is only valid in protonic acid but not in non-protonic acid
  2. There are a number of acid-base reaction in which no transfer of protons takes place.

Eg:- CaO + SO3 \rightleftharpoons CaSO4

(Base)   (acid)   (salt)

  1. It fails to explain the acid-base reactions in the non-aquose solvent.

Eg:- SO2 + SO2  \rightleftharpoonsSO2+ SO3– –

  1. It also fails to explain the acid nature of the compounds such as FeCL3, ALCL3, etc

therefore, the Brosted-Lowry Concept as Acid and Base is explained above.