Question

Which statements are true In the ionic strength range ${\mathbf{0}}_{\mathbf{}\mathbf{I}}\mathbf{0}\mathbf{.}\mathbf{1}\mathbf{M}\mathbf{,}$

activity coefficients decrease with

a) increasing ionic strength

b) increasing ionic charge

c) decreasing hydrated radius

Short answer

The above relationship shows that, all the three statements are true for the given condition.

Step-by-step solution

Define the Extended Debye-Huckel equation:

The extended Debye-Huckel equation describes the link between activity coefficient and ionic strength.

$\mathbf{logy}\mathbf{=}\frac{\mathbf{-}\mathbf{0}\mathbf{.}\mathbf{51}{\mathbf{z}}^{\mathbf{2}}\sqrt{\mathbf{\mu }}}{\mathbf{1}\mathbf{+}\mathbf{(}\mathbf{a}\sqrt{\mathbf{\mu }}\mathbf{/}\mathbf{305}\mathbf{)}}$

where,

$\mathit{\gamma }\mathbf{}\mathbf{-}$activity coefficient of ion

$\mathit{\mu }\mathbf{}\mathbf{-}$ionic strength of solution

$\mathit{\alpha }\mathbf{}\mathbf{-}$ size of ion.

Step 2:Explanation.

With increasing ionic strength, increasing ionic charge, and decreasing hydrated radius, activity coefficients drop in the 0.01M ionic strength range.

An expanded Debye-Huckel equation describes the link between activity coefficient and ionic strength.

$\mathrm{logy}=\frac{-0.51{\mathrm{z}}^2\sqrt{\mathrm{\mu }}}{1+(\mathrm{a}\sqrt{\mathrm{\mu }}/305)}$

where,

$\gamma$- activity coefficient of ion

$\mu$- ionic strength of solution

$\alpha$- size of ion

The above relationship shows that, all the three statements are true for the given condition.