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Ionic Compounds: Chemical Formula

The pKa of ac...

Question

The ${pK}_{a}$ of acetic acid and ${pK}_{b}$ of ammonium hydroxide are $4.76$ and $4.75$ respectively. Calculate the pH of ammonium acetate solution.

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Solution

Given,
$p K_{a} (C H_{3} C O O H) = 4.76$ and $p K_{b} (N H_{4} O H) = 4.75$

Step 1: Salt type
Ammonium acetate $(C H_{3} C O O N H_{4})$ is a salt of weak acid, acetic acid $(C H_{3} C O O H)$ and weak base, ammonium hydroxide $(N H_{4} O H)$ .

The reaction taking place is:
$C H_{3} C O O H + N H_{4} O H ⇌ C H_{3} C O O N H_{4} + H_{2} O$

Step $2$ : Formula of pH
For salt of weak acid and weak base, the pH of salt in solution is given as:
$p H = 7 + \frac{1}{2} [p K_{a} - p K_{b}]$

Step $3$ : pH value
So,
$p H = 7 + \frac{1}{2} [4.76 - 4.75] = 7 + \frac{1}{2} [0.01] = 7 + 0.005 = 7.005$

Final answer:
$7.005$

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Similar questions

p K_{a}

of acetic acid and

p K_{b}

N H_{4} O H

4.76

4.75

. Calculate the

p H

of ammonium acetate ions.

p K_{a}

C H_{3} C O O H

p K_{b}

N H_{4} O H

4.76

4.75

, respectively. Calculate the hydrolysis constant of ammonium acetate

(C H_{3} C O O N H_{4})

298

K and also the degree of hydrolysis and pH of its (a)

0.01

0.04

ph of solution containing acetic acid -pka=4.76and NH4OH pkb=4.75

Q. Acetic acid and Ammonium hydroxide are ..............and ..........respectively.

K_{a}

for acetic acid is

1.77 \times 10^{- 5}

K_{b}

for ammonium hydroxide is

1.82 \times 10^{- 5}

.
Calculate the pH of an aqueous solution of ammonium acetate

(C H_{3} C O O N H_{4})

25^{\circ} C

.

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Ionic Compounds: Chemical Formula

Standard IX Chemistry

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