Exam

JEE Main

Year

2025

Date

23 January

Shift

Morning Shift

Subject

Chemistry

Chapter

Ionic Equilibrium

JEE Main 2025 · 23 January · Morning Shift · Chemistry · Ionic Equilibrium

If 1 mM solution of ethylamine produces pH=9 , then the ionization...

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.]

Step-by-step solution

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{\text{ NH }}_3^{+}\right][\stackrel{\ominus}{\mathrm{O}} \mathrm{H}]}{\left[\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2\right]} $\Rightarrow K_{\mathrm{b}}=\frac{10^{-5} \times 10^{-5}}{10^{-3}}=10^{-7}$