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Electrolytes

Calculate the...

Question

Calculate the pH of an acidic buffer solution containing $1.2 M C H_{3} C O O N a$ and $0.8 M C H_{3} C O O H$ .
For acetic acid $K_{a} = 1.8 \times 10^{- 5}$

A

4.92

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B

3.66

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C

6.89

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D

5.88

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Solution

The correct option is A 4.92
$p K_{a} = - l o g (K_{a}) p K_{a} = - l o g (1.8 \times 10^{- 5}) p K_{a} = (5 - 0.26) = 4.74$
$p H$ for acidic buffer:

$p H = p K_{a} + l o g \frac{[s a l t]}{[a c i d]}$
$p H = p K_{a} + l o g \frac{[C H_{3} C O O N a]}{[C H_{3} C O O H]}$
$p H = 4.74 + l o g (\frac{1.2}{0.8}) p H = 4.74 + l o g (1.5) p H = 4.74 + 0.18 = 4.92$

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Similar questions

Q. What will be the new

p H

0.01 m o l

N a O H

1 L

buffer solution that is

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in sodium acetate

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Dissociation constant

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1.8 \times 10^{- 5}

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