The pH of 0.05 M ( CH 3 COO ) 2 Ca ( aq . ) so l u t i o ni s − [0pt]

Question

The pH of 0.05 M ( CH 3 ​ COO ) 2 ​ Ca ( aq . ) so l u t i o ni s − [0pt]

TestHub · Accepted Answer

Explain Question:

Find the pH of a salt formed by a weak acid and a strong base.

Concept:

Salt Hydrolysis of Weak Acid and Strong Base.

Solution:

Calcium acetate is a salt of a weak acid (acetic acid) and a strong base (calcium hydroxide).

In water, the acetate ion undergoes anionic hydrolysis to produce OH⁻ ions, making the solution basic.

Calculation:

Total concentration of acetate ions $[C H_{3} CO O^{-}] = 2 \times 0.05 = 0.1 M = 1 0^{- 1} M$

Given $p K_{b} = 9$ , then $p K_{a} = p K_{w} - p K_{b} = 14 - 9 = 5$ .

Using the formula for pH of a salt of WA/SB:

$p H = \frac{1}{2} (p K_{w} + p K_{a} + lo g C)$

$p H = \frac{1}{2} (14 + 5 + lo g (1 0^{- 1}))$

$p H = \frac{1}{2} (19 - 1)$

$p H = \frac{18}{2}$

$p H = 9$

Final Answer: Option (B)

Chemistry - Ionic Equilibrium Question with Solution | TestHub