Question

Calculate the pH of the buffer solution consists of 0.005 M weak acid and 0.02 M of its salt with strong base BA. [\(\text{p}K_{a}=3.4437\)]

• A. \(4.046\)
• B. \(2.842\)
• C. \(3.7447\)
• D. \(3.1437\)

Hint:

Use the Henderson-Hasselbalch equation for an acidic buffer with the given concentrations.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
For an acidic buffer, \(\text{pH}=\text{p}K_a+\log\dfrac{[\text{salt}]}{[\text{acid}]}\).

Step 2: Substitute
\([\text{salt}]=0.02\) M and \([\text{acid}]=0.005\) M, so the ratio is 4. \(\log 4=0.6021\).

Step 3: Calculation
\(\text{pH}=3.4437+0.6021=4.0458\approx 4.046\).

Final Answer:
The pH of the buffer is about 4.046, which is option (A). \[ \boxed{\text{(A) }4.046} \]