Q18.7P - Chemistry: Molecular Nature Of Matter And Change

Question

Question: Which of the following are Arrhenius bases? 

(a) ${\mathbf{\text{H}}}_{\mathbf{\text{3}}}{\mathbf{\text{AsO}}}_{\mathbf{\text{4}}}$

(b) ${\mathbf{\text{Ba(OH)}}}_{\mathbf{\text{2}}}$

(c) $\mathbf{\text{HClO}}$

(d) $\mathbf{\text{KOH}}$

Step-by-Step Solution

Answer

(a) ${\text{H}}_{\text{3}}{\text{AsO}}_{\text{4}}$ is not an Arrhenius base but an Arrhenius acid as it produces ${\text{H}}^{\text{ + }}$ ions.

(b) ${\text{Ba(OH)}}_{\text{2}}$ is an Arrhenius base as it produces ${\text{OH}}^{\text{ - }}$ ions.

(c) $HClO$ is not an Arrhenius base but an Arrhenius acid as it produces ${\text{H}}^{\text{ + }}$ ions.

(d)  is an Arrhenius base as it produces ${\text{OH}}^{\text{ - }}$ ions.

Step 1: Concept Introduction

An Arrhenius base is a substance that raises the concentration of the ${\mathbf{\text{OH}}}^{\mathbf{\text{ - }}}$ ion in an aqueous solution. Classic Arrhenius bases are ionic compounds containing the ${\mathbf{\text{OH}}}^{\mathbf{\text{ - }}}$ ion

Step 2: (a) Is H 3 AsO 4 an Arrhenius Base

The reaction for ${\text{H}}_{\text{3}}{\text{AsO}}_{\text{4}}$ is as follows –

${\text{H}}_{\text{3}}{\text{AsO}}_{\text{4}}\rightleftharpoons {\text{ H}}^{\text{ + }}{\text{ + H}}_{\text{2}}{\text{AsO}}_{\text{4}}^{\text{ - }}$

The dissociation ${\text{H}}_{\text{3}}{\text{AsO}}_{\text{4}}$ of in water produced a ${\text{H}}^{\text{ + }}$ ion. 

Therefore, ${\text{H}}_{\text{3}}{\text{AsO}}_{\text{4}}$ is not an Arrhenius base.

Step 3: (b) Is Ba(OH) 4 an Arrhenius Base

The reaction for ${\text{Ba(OH)}}_{\text{4}}$ is as follows –

${\text{Ba(OH)}}_{\text{4}}\rightleftharpoons {\text{ Ba}}^{\text{2 + }}{\text{ + 2OH}}^{\text{ - }}$

The dissociation of ${\text{Ba(OH)}}_{\text{4}}$ in water produced ${\text{OH}}^{\text{ - }}$ ions. 

Therefore, ${\text{Ba(OH)}}_{\text{4}}$ is an Arrhenius base.

Step 4:(c) Is HClO an Arrhenius Base

The reaction for $HClO$ is as follows –

$HClO\rightleftharpoons {\text{ H}}^{\text{ + }}{\text{ + ClO}}^{\text{ - }}$

The dissociation of $HClO$ in water produced a ${\text{H}}^{\text{ + }}$ ion. 

Therefore, $HClO$ is not an Arrhenius base.

Step 5: (d) Is KOH an Arrhenius Base

The reaction for $\text{KOH}$ is as follows –

$\text{KOH }\rightleftharpoons {\text{ K}}^{\text{ + }}{\text{ + OH}}^{\text{ - }}$

The dissociation of $\text{KOH}$ in water produced a ${\text{OH}}^{\text{ - }}$ ion. 

Therefore, $\text{KOH}$ is an Arrhenius base.