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The pH of an acid buffer can be raised by 2 units by:

Option: 1

Increasing the concentration of both weak acid and salt by two moles


Option: 2

Increasing the concentration of both the acid and salt by 10 times.


Option: 3

Increasing the concentration of the salt by 10 times and decreasing concentration of the acid by 10 times.


Option: 4

Diluting the solution by 10 times.


Answers (1)

best_answer

As we have learned,

\begin{array}{l}{\mathrm{pH}_{1}=\mathrm{p} K_{a}+\log \left(\frac{\mathrm{Salt}}{\mathrm{Acid}}\right)} \\\\ {\mathrm{pH}_{1}=\mathrm{p} K_{a}+\log \left(\frac{x_{1}}{y_{1}}\right)} \\\\ {\mathrm{pH}_{2}=\mathrm{p} K_{a}+\log \left(\frac{x_{2}}{y_{2}}\right)} \\\\ {\mathrm{pH}_{2}-\mathrm{pH}_{1}=\log \frac{x_{2}}{y_{2}}-\log \frac{x_{1}}{y_{1}}} \\\\ \mathrm{pH}_{2}-\mathrm{pH}_{1}{=\log \left(\frac{x_{2} / y_{2}}{x_{1} / y_{1}}\right)}\end{array}
\therefore \frac{x_{2} / y_{2}}{x_{1} / y_{1}}=10^{2}=100

This is only possible if the concentration of salt is increased by 10 times and the concentration of acid is decreased by 10 times.

Therefore,option(3) is correct

 

Posted by

Irshad Anwar

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