Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • Medical
  • A 0.1 M solution of HCl has a degree of dissociation of 0.01. What is the dissociation constant for the acid?Option: 1

A 0.1 M solution of HCl has a degree of dissociation of 0.01. What is the dissociation constant for the acid?

Option: 1

1.0 \times 10^{-4}


Option: 2

1.0 \times 10^{-5}


Option: 3

1.0 \times 10^{-5}


Option: 4

1.0 \times 10^{-7}


Answers (1)

best_answer

The degree of dissociation \alpha for a weak electrolyte is given by the ratio of the concentration of the dissociated ions to the initial concentration of the electrolyte:
\mathrm{\alpha=\frac{\left[X^{-}\right]}{[H X]}}
Where X^{-} is the anion, \mathrm{HX} is the undissociated acid, and "[ ]" denotes the concentration in \mathrm{mol} / \mathrm{L}.
For \mathrm{HCl}, since it is a strong electrolyte, it undergoes complete dissociation:

\mathrm{HX} \rightarrow \mathrm{H}^{+}+\mathrm{Cl}^{-}
So the degree of dissociation can be calculated as:
\alpha=\frac{[\mathrm{Cl}^{-}]}{[\mathrm{HCl}]} =0.01
Since the initial concentration of \mathrm{HCl} \text{ is }0.1 \mathrm{M}, the concentration of \mathrm{Cl}^{-} is also 0.1 \times 0.01=0.001 \mathrm{M}
The dissociation constant \left(K_a\right) for \mathrm{HCl} is given by:
\mathrm{K_a=\frac{[H^+][\mathrm{Cl}^{-}]} {[\mathrm{HCl}]}}
At equilibrium, the concentration of \mathrm{H^+} is equal to the degree of dissociation times the initial concentration of \mathrm{HCl} :
\mathrm{[H^+]=\alpha[H \mathrm{Cl}]=0.01 \times 0.1=0.001 \mathrm{M}}
Substituting the values into the equation for \left(K_a\right), we get:
\mathrm{K_a=\frac{(0.001)^2}{0.099}=1.0 \times 10^{-5}}

Posted by

SANGALDEEP SINGH

View full answer

NEET 2024 Most scoring concepts

    Just Study 32% of the NEET syllabus and Score up to 100% marks

Similar Questions

Trending Articles/News

anam-khan

17 left in NEET toppers list 2024 as physics question strips 44 of top ranks
anam-khan

NEET Revised Result 2024: Joy and disappointment as all-India ranks change by thousands of places
anam-khan

NEET UG 2024 cut-offs drop for all categories; final scorecard out at neet.ntaonline.in

Latest Question