A buffer mixture of acetic acid and potassium acetate has PH=5.24. The ratio of [CH3COO-]/[CH3COOH] in this buffer is, (pKa=4.74)

  • Option 1)

    3:1

  • Option 2)

    1:3

  • Option 3)

    1:1

  • Option 4)

    1:2

 

Answers (1)
V Vakul

As learnt in

Buffer Solutions -

The solutions which resist change in pH on dilution or with addition of small amounts of acid or alkali are called buffer solution.  

- wherein

Many body fluids  e.g.  blood

 

 pH = pKa+\log \frac{\left ( salt \right )}{\left ( acid \right )}

for a buffer solution of weak acid and it's salt

\Rightarrow 5.24 = 4.74 +\log \frac{\left [ CH_{3}COO^{-} \right ]}{\left [ CH_{3}COOH \right ]}

\Rightarrow \log \frac{\left [ CH_{3}COO^{-} \right ]}{\left [ CH_{3}COOH \right ]} = 0.5

\Rightarrow \frac{\left [ CH_{3}COO^{-} \right ]}{\left [ CH_{3}COOH \right ]}\sim 3


Option 1)

3:1

This option is correct

Option 2)

1:3

This option is incorrect

Option 3)

1:1

This option is incorrect

Option 4)

1:2

This option is incorrect

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