Question

How is the Bronsted – Lowry definition of an acid different from the Arrhenius definition?
A.The Arrhenius definition says that all acids must be in aqueous solution. The Bronsted – Lowry definition says that an acid is anything that can donate a proton.
B.The Arrhenius definition says that an acid is anything that can donate a proton. The Bronsted – Lowry definition says that all acids must be in aqueous solution.
C.The Arrhenius definition says that anything that donates a pair of electrons is an acid. The Bronsted – Lowry definition says that an acid is anything that can donate a proton.
D.The Arrhenius definition says that anything that donates a pair of electrons is an acid. The Bronsted – Lowry definition says that all acids must be in aqueous solution.
E.The arrhenius definition says that all acid must be in aqueous solution. The bronsted lowry definition says that anything that can donate a pair of electrons is an acid.

Answer 1

Hint: Acid is defined as a molecule or ion that has the ability to donate protons and it is capable of forming a covalent bond with an electron pair. There are some common acids such as hydrochloric acid, acetic acid, citric acid, sulphuric acid. When an acid reacts with a base it forms a conjugate base.

Complete answer:
The Bronsted – Lowry theory is defined as the acid base reaction theory in which when acid reacts with a base, the acid forms a conjugate base and the base forms its conjugate acid with the help of exchange of protons.
 $HA+B\rightleftharpoons {{A}^{-}}+H{{B}^{+}}$
where, $HA$ is an acid and $B$ is a base, and ${{A}^{-}}$ is the conjugate base and $H{{B}^{+}}$ is the conjugate acid. In this, acid can lose a proton and become its conjugate base and base accepts a proton to become its conjugate acid.
The Bronsted – Lowry acid is defined as a species that has the ability to donate a proton to another molecule. They are also known as proton donors.
According to the Arrhenius theory, acid is the substance that has the ability to donate ${{H}^{+}}$ ions when dissolved in an aqueous solution. The aqueous solution helps in increasing the concentration of ${{H}^{+}}$ ions in the solution. For example, when hydrochloric acid is dissolved in water, it undergoes dissociation that gives ${{H}^{+}}$ ion and $C{{l}^{-}}$ ion. When $HCl$ is dissolved in water, it increases the ${{H}^{+}}$ ions and forms the hydronium ion.
Let us see a chemical reaction
 $HC{{l}_{(aq)}}+{{H}_{2}}{{O}_{(l)}}\to {{H}_{3}}{{O}_{(aq)}}+C{{l}^{-}}_{(aq)}$
Arrhenius theory says that acid must be in aqueous solution.
Therefore, the option (A) is correct, that is, The Arrhenius definition says that all acids must be in aqueous solution. The Bronsted – Lowry definition says that an acid is anything that can donate a proton.

Note: There is a limitation of Arrhenius theory that this theory is only applicable in aqueous solution.
-When an acid donates a proton, it gives conjugate base as a product and when base accepts a proton, it gives conjugate acid as a product.