Ionic Equilibria

Chemistry Level 3

Consider the following reaction

$\large{HA \rightleftharpoons H^{+}+A^{-}} ;\space \space \space \alpha_{1}$

$\large{HB \rightleftharpoons H^{+}+B^{-}}; \space \space \space \alpha_{2}$

Here $\alpha_{1},\alpha_{2}$ are degree of dissociation of the respective reactions.

Given that concentration of $H^{+}$ are equal at the equilibrium of the two reactions.

If volume of container in which reaction 1 is taking place be $1 L$ and Reaction 2 be $2 L$ .

Initially $n_{HA}=2$ moles and $n_{HB}=6$ moles.

If $\dfrac{\alpha_{1}}{\alpha_{2}} = \dfrac{m}{n}$ where $gcd(m,n)=1$ and m and n are positive numbers.

Find the value of $m+n$

ORIGINAL

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The answer is 5.

1 solution

Tapas Mazumdar
Oct 18, 2017

Let initial conc. of HA be $c_1 = \dfrac{n_{\text{HA}}}{V_1} = \dfrac{2}{1} = 2$ and initial conc. of HB be $c_2 = \dfrac{n_{\text{HB}}}{V_2} = \dfrac{6}{2} = 3$ .

The conc. of $\text{H}^{+}$ ions at equilibrium in containers 1 and 2 are respectively $c_1 \alpha_1$ and $c_2 \alpha_2$ . From the information given

$c_1 \alpha_1 = c_2 \alpha_2 \implies \dfrac{\alpha_1}{\alpha_2} = \dfrac{c_2}{c_1} = \dfrac{3}{2}$

which gives $m=3, n =2$ and $m+n = \boxed{5}$ .

Howz the question? Created by me.

Md Zuhair - 3 years, 7 months ago

@Md Zuhair The question statement is incorrect , alpha is the degree of dissociation and not dissociation constant , the two are different things.

Ankit Kumar Jain - 3 years, 3 months ago

There's still a small typo It's spelt dissocition not "dissociation" XD

Suhas Sheikh - 2 years, 11 months ago

Also , in problem EQUILIBRIUM - 2 , combustion reactions are not reversible.

Ankit Kumar Jain - 3 years, 3 months ago

oh. thats true

Md Zuhair - 3 years, 3 months ago

Ionic Equilibria

ORIGINAL

The answer is 5.

1 solution

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