Q7P - Chemistry: Molecular Nature Of Matter And Change

Question

Which of the following are Arrhenius bases? 

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

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

(c) $\mathbf{HCIO}$

(d) $\mathbf{KOH}$

Step-by-Step Solution

Answer

(a) ${\mathrm{H}}_3{\mathrm{AsO}}_4$ is not an Arrhenius base but an Arrhenius acid as it produces ${\mathrm{H}}^{+}$ ions.

(b) $\mathrm{Ba}{\left(\mathrm{OH}\right)}_4$ is an Arrhenius base as it produces ${\mathrm{OH}}^{-}$ ions.

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

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

Step 1: Concept Introduction

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

Step 2: Is H 3 AsO 4 an Arrhenius Base

(a)

The reaction for ${\mathrm{H}}_3{\mathrm{AsO}}_4$ is as follows –

${\mathrm{H}}_3{\mathrm{AsO}}_4 \mathrm{֏} {\mathrm{H}}^{+} + {\mathrm{H}}_2{\mathrm{AsO}}_4^{-}$

The dissociation of ${\mathrm{H}}_3{\mathrm{AsO}}_4$ in water produced a ${\mathrm{H}}^{+}$ ion.

Therefore, ${\mathrm{H}}_3{\mathrm{AsO}}_4$ is not an Arrhenius base.

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

(b)

The reaction for is as follows –

$\mathrm{Ba}{\left(\mathrm{OH}\right)}_4 \mathrm{֏} {\mathrm{Ba}}^{2+} + 2{\mathrm{OH}}^{-}$

The dissociation of $\mathrm{Ba}{\left(\mathrm{OH}\right)}_4$ in water produced ${\mathrm{OH}}^{-}$ ions. 

Therefore, $\mathrm{Ba}{\left(\mathrm{OH}\right)}_4$ is an Arrhenius base.

Step 4:Is HCIO an Arrhenius Base

(c)

The reaction for $\mathrm{HCIO}$ is as follows –

$\mathrm{HCIO} \mathrm{֏} {\mathrm{H}}^{+} + {\mathrm{CIO}}^{-}$

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

Therefore, $\mathrm{HCIO}$ is not an Arrhenius base.

Step 5:Is KOH an Arrhenius Base

(d)

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

$\mathrm{KOH} \mathrm{֏} {\mathrm{K}}^{+} + {\mathrm{OH}}^{-}$

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

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