Chapter 21, Problem 8STP

3

Interpretation Introduction

Interpretation:

The Brønsted-Lowry acid should be determined in the forward reaction of the given reaction.

1. $\text{HF}$
2. ${\text{H}}_{\text{2}}\text{O}$
3. ${\text{H}}_{\text{3}}{\text{O}}^{+}$
4. ${\text{F}}^{-}$

Concept introduction:

According to Brønsted Lowry model:

Acids are those compounds which donates a proton to another compound whereas bases are those compounds which accept a proton from another substance.

Answer to Problem 8STP

$\text{HF}$ is a Brønsted Lowry acid as it donate a proton to ${\text{H}}_{\text{2}}\text{O}$. Thus, option (A) is correct.

Explanation of Solution

Acids are defined as compounds which donates proton to base whereas bases are defined as compounds which accepts proton from acids.

The given reaction is:

${\text{HF+H}}_{\text{2}}\text{O}\rightleftharpoons {\text{H}}_{\text{3}}{\text{O}}^{\text{+}}{\text{+F}}^{\text{-}}$

According to Brønsted Lowry model, acids are those compounds which have ability to donate protons.

In the given reaction, $\text{HF}$ donate one proton ( ${\text{H}}^{\text{+}}$ ) to ${\text{H}}_{\text{2}}\text{O}$ which results in the formation of hydronium ion ( ${\text{H}}_{\text{3}}{\text{O}}^{+}$ ). Thus, in the given $\text{HF}$ is a Brønsted Lowry acid and ${\text{H}}_{\text{2}}\text{O}$ is aBrønsted Lowry base as it accepts proton from acid.

${\text{HF + H}}_{\text{2}}\text{O}\rightleftharpoons {\text{H}}_{\text{3}}{\text{O}}^{\text{+}}{\text{ + F}}^{\text{-}}$

Brønsted

Lowry acid

Hence, option (A) is correct.