Question

Consider this reaction: H3BO3(aq) + HS-(aq) H2BO3-(aq) + H2S(aq) What is the sequence of Brønsted-Lowry acids and bases? A.base + acid acid + base B.acid + base acid + base C.acid + base base + acid D.base + acid base + acid

Answer 1

Answer : The correct option is (C).

Explanation :

According to the Bronsted Lowry concept, Bronsted Lowry-acid is a substance that donates one or more hydrogen ion in a reaction and Bronsted Lowry-base is a substance that accepts one or more hydrogen ion in a reaction.

Or we can say that, conjugate acid is proton donor and conjugate base is proton acceptor.

The given equilibrium reaction will be,

`H_3BO_3(aq)+HS^-(aq)\rightleftharpoons H_2BO_3^-(aq)+H_2S(aq)`

In this reaction,
`H_3BO_3` is an acid that donate a proton or hydrogen to
`HS^-` base and it forms
`H_2BO_3^-` and
`H_2S` are conjugate base and acid respectively.

That means,
`H_3BO_3` and
`HS^-` are acid and base and
`H_2BO_3^-` and
`H_2S` are conjugate base and acid respectively.

The general sequence of Brønsted-Lowry acids and bases is:

`\text{Acid}+\text{Base}\rightleftharpoons \text{Conjugate Base}+\text{Conjugate Acid}`

From the given option we conclude that the correct sequence will be:

`\text{Acid}+\text{Base}\rightleftharpoons \text{Base}+\text{Acid}`

Hence, the correct option is (C)
`\text{Acid}+\text{Base}\rightleftharpoons \text{Base}+\text{Acid}`

Answer 2

Answer: The correct answer is Option C.

Step-by-step explanation:

According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.

For the given chemical equation:

`H_3BO_3(aq.)+HS^-(aq.)\rightarrow H_2BO_3^-(aq.)+H_2S(aq.)`

Here,
`H_3BO_3` is loosing a proton, thus it is considered as an acid and after losing a proton, it forms
`H_2BO_3^-` which is a conjugate base.

And,
`HS^-` is gaining a proton, thus it is considered as a base and after gaining a proton, it forms
`H_2S` which is a conjugate acid.

The sequence of the acids and bases in the above equation are:

`Acid+Base\rightarrow Base+Acid`

Hence, the correct answer is Option C.