Question

What is the ph of a solution that consists of 0.50 m h2c6h6o6 (ascorbic acid) and 0.75 m nahc6h6o6 (sodium ascorbate)? ka = 6.8 ´ 10-5 question 12 options: 1) 3.76 2) 3.99 3) 4.34 4) 4.57 5) 5.66?

Answer 1

Answer:

4.34.

Explanation:

• For acidic buffer:

∵ pH = pKa + log [salt]/[Acid]

∴ pH = - log(Ka) + log [salt]/[Acid]

∴ pH = - log(6.8 x 10⁻⁵) + log(0.75)/(0.50)

∴ pH = 4.167 + 0.176 = 4.343 ≅ 4.34.