Find out the ionisation constant of a weak ac | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(B) For a weak acid $HA$,the dissociation equilibrium is $HA \rightleftharpoons H^+ + A^-$. The ionisation constant $K_a$ is given by $K_a = \frac{C \

Vedclass · Accepted Answer

$K_a = \frac{C (\Lambda_m^c)^2}{\Lambda_m^o(\Lambda_m^o - \Lambda_m^c)}$

Vedclass · Answer

(B) For a weak acid $HA$,the dissociation equilibrium is $HA ightleftharpoons H^+ + A^-$. The ionisation constant $K_a$ is given by $K_a = \frac{C \alpha^2}{(1 - \alpha)}$,where $\alpha$ is the degree of dissociation. The degree of dissociation $\alpha$ is related to molar conductivity $\Lambda_m^c$ and limiting molar conductivity $\Lambda_m^o$ as $\alpha = \frac{\Lambda_m^c}{\Lambda_m^o}$. Substituting $\alpha$ into the expression for $K_a$: $K_a = \frac{C 	imes (\frac{\Lambda_m^c}{\Lambda_m^o})^2}{1 - \frac{\Lambda_m^c}{\Lambda_m^o}} = \frac{C 	imes \frac{(\Lambda_m^c)^2}{(\Lambda_m^o)^2}}{\frac{\Lambda_m^o - \Lambda_m^c}{\Lambda_m^o}} = \frac{C (\Lambda_m^c)^2}{\Lambda_m^o(\Lambda_m^o - \Lambda_m^c)}$.

Find out the ionisation constant of a weak acid $(HA)$ in terms of $\Lambda_m^o$ and $\Lambda_m^c$. (Given $\alpha$ cannot be ignored with respect to $1$)

Similar Questions

Limiting molar conductivity of $NH_4OH$ [i.e.,$\Lambda ^o_{m(NH_4OH)}$] is equal to:

What is the conductivity of $0.01 \ M$ $NaCl$ solution if the resistance and cell constant of the $NaCl$ solution are $375 \ \Omega$ and $0.5 \ cm^{-1}$ respectively at $298 \ K$?

Molar conductivities at infinite dilution $\wedge_{m}^{\circ}$ for $Ba(OH)_2$,$BaCl_2$ and $NH_4Cl$ are $457.0$,$240.6$ and $213.0 \ S \ cm^2 \ mol^{-1}$ respectively. The $\wedge_{m}^{\circ}$ for ammonium hydroxide (in $S \ cm^2 \ mol^{-1}$) is (in $.2$)

Metallic and ionic conductivity depends on which factors?

The molar conductances of $NaCl$,$HCl$,and $CH_3COONa$ at infinite dilution are $126.45$,$426.16$,and $91 \ \Omega^{-1} \ cm^2 \ mol^{-1}$ respectively. The molar conductance of $CH_3COOH$ at infinite dilution is .............. $\Omega^{-1} \ cm^2 \ mol^{-1}$.

Vedclass Test Series

Exam Paper Generator

Online Exam Module