Explain a general step-wise approach to evaluate the $pH$ of the weak electrolyte.
Explain a general step-wise approach to evaluate the $pH$ of the weak electrolyte.
Step-$1$ : The species present before dissociation are identified as Bronsted-Lowry acid/base.
Step-$2$: Balanced equations for all possible reaction. i.e. with a species acting both as acid as well as base are written.
Step-$3$: The reaction with the higher $\mathrm{K}_{a}$ is identified as the primary reaction whilst the other is a subsidiary reaction.
Step-$4$: Enlist in a tabular form the following values for each of the species in the primary reaction. $(i)$ Initial concentration $c$, $(ii)$ Change in concentration on proceeding to equilibrium in term of $(\alpha)$, degree of ionization. $(iii)$ Equilibrium concentration.
Step-$5$ : Substitute equilibrium concentrations into equilibrium constant equation for principal reaction and solve for $\alpha$.
Step-$6$: Calculate the concentration of species in principal reaction.
Step-$7$: Calculate $\mathrm{pH}=-\log \left[\mathrm{H}_{3} \mathrm{O}^{+}\right]$.
Similar Questions
$5\%$ ionization is occur in $0.01$ $M$ $C{H_3}COOH$ solution. Calculate its dissociation constant.
$5\%$ ionization is occur in $0.01$ $M$ $C{H_3}COOH$ solution. Calculate its dissociation constant.
$0.01$ moles of a weak acid $HA \left( K _{ a }=2.0 \times 10^{-6}\right)$ is dissolved in $1.0\, L$ of $0.1\, M\, HCl$ solution. The degree of dissociation of $HA$ is ............. $\times 10^{-5}$
(Round off to the Nearest Integer).
[Neglect volume change on adding $HA$. Assume degree of dissociation $<< 1]$
$0.01$ moles of a weak acid $HA \left( K _{ a }=2.0 \times 10^{-6}\right)$ is dissolved in $1.0\, L$ of $0.1\, M\, HCl$ solution. The degree of dissociation of $HA$ is ............. $\times 10^{-5}$
(Round off to the Nearest Integer).
[Neglect volume change on adding $HA$. Assume degree of dissociation $<< 1]$
- [JEE MAIN 2021]
What is the $pH$ of $0.001 \,M$ aniline solution? The ionization constant of aniline can be taken from Table . Calculate the degree of ionization of aniline in the solution. Also calculate the ionization constant of the conjugate acid of aniline.
Base
$K _{ b }$
Dimethylamine, $\left( CH _{3}\right)_{2} NH$
$5.4 \times 10^{-4}$
Triethylamine, $\left( C _{2} H _{5}\right)_{3} N$
$6.45 \times 10^{-5}$
Ammonia, $NH _{3}$ or $NH _{4} OH$
$1.77 \times 10^{-5}$
Quinine, ( $A$ plant product)
$1.10 \times 10^{-6}$
Pyridine, $C _{5} H _{5} N$
$1.77 \times 10^{-9}$
Aniline, $C _{6} H _{5} NH _{2}$
$4.27 \times 10^{-10}$
Urea, $CO \left( NH _{2}\right)_{2}$
$1.3 \times 10^{-14}$
What is the $pH$ of $0.001 \,M$ aniline solution? The ionization constant of aniline can be taken from Table . Calculate the degree of ionization of aniline in the solution. Also calculate the ionization constant of the conjugate acid of aniline.
| Base | $K _{ b }$ |
| Dimethylamine, $\left( CH _{3}\right)_{2} NH$ | $5.4 \times 10^{-4}$ |
| Triethylamine, $\left( C _{2} H _{5}\right)_{3} N$ | $6.45 \times 10^{-5}$ |
| Ammonia, $NH _{3}$ or $NH _{4} OH$ | $1.77 \times 10^{-5}$ |
| Quinine, ( $A$ plant product) | $1.10 \times 10^{-6}$ |
| Pyridine, $C _{5} H _{5} N$ | $1.77 \times 10^{-9}$ |
| Aniline, $C _{6} H _{5} NH _{2}$ | $4.27 \times 10^{-10}$ |
| Urea, $CO \left( NH _{2}\right)_{2}$ | $1.3 \times 10^{-14}$ |
The $K_a$ of monobasic acid $A, B$ and $C$ are $10^{-6}, 10^{-8}$ and $10^{-10}$ respectively. The concentrations of $A, B$ and $C$ are respectively. $0.1\,M$, $0.01\, M$ and $0.001\, M$. Which of the following is correct for $pOH$ of $A, B$ and $C$ ?
The $K_a$ of monobasic acid $A, B$ and $C$ are $10^{-6}, 10^{-8}$ and $10^{-10}$ respectively. The concentrations of $A, B$ and $C$ are respectively. $0.1\,M$, $0.01\, M$ and $0.001\, M$. Which of the following is correct for $pOH$ of $A, B$ and $C$ ?
Calculate $\left[ {{S^{ - 2}}} \right]$ and $\left[ {H{S^{ - 2}}} \right]$ of the solution which contain$0.1$ $M$ ${H_2}S$ and $0.3$ $M$ $HCl$.
[ ${H_2}S$ of ${K_a}\left( 1 \right) = 1.0 \times {10^{ - 7}}$ and ${K_a}\left( 2 \right) = 1.3 \times {10^{ - 13}}$ ]
Calculate $\left[ {{S^{ - 2}}} \right]$ and $\left[ {H{S^{ - 2}}} \right]$ of the solution which contain$0.1$ $M$ ${H_2}S$ and $0.3$ $M$ $HCl$.
[ ${H_2}S$ of ${K_a}\left( 1 \right) = 1.0 \times {10^{ - 7}}$ and ${K_a}\left( 2 \right) = 1.3 \times {10^{ - 13}}$ ]