If 1 mM solution of ethylamine produces $\mathrm{pH}=9$, then the ionization constant $\left(\mathrm{K}_{\mathrm{b}}\right)$ of ethylamine is $10^{-x}$. The value of $x$ is ______ (nearest integer).
[The degree of ionization of ethylamine can be neglected with respect to unity.]

Question

Aicharya · Accepted Answer

Given, $\mathrm{P}^{\mathrm{H}}=9 \Rightarrow \mathrm{P}^{\mathrm{OH}}=5 \Rightarrow[\stackrel{\ominus}{\mathrm{OH}}]=10^{-5} \mathrm{M}$
Now, $\mathrm{K}_{\mathrm{b}}=\frac{\left[\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_3^{+}\right][\stackrel{\ominus}{\mathrm{O}} \mathrm{H}]}{\left[\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2\right]}$
$\Rightarrow K_{\mathrm{b}}=\frac{10^{-5} \times 10^{-5}}{10^{-3}}=10^{-7}$

If 1 mM solution of ethylamine produces $\mathrm{pH}=9$, then the ionization constant…

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