Answer:
2.6
Explanation:
Step 1: Given and required data
- Concentration of butanoic acid (Ca): 0.35 M
- pKa of butanoic acid: 4.82
Step 2: Calculate the acid dissociation constant (Ka) of butanoic acid
We will use the following expression.
pKa = -log Ka
Ka = antilog - pKa
Ka = antilog -4.82 = 1.51 × 10⁻⁵
Step 3: Calculate [H⁺] of the solution
For a weak acid, we can use the following expression.
[H⁺] = √(Ca × Ka)
[H⁺] = √(0.35 × 1.51 × 10⁻⁵) = 2.3 × 10⁻³ M
Step 4: Calculate the pH of the solution
pH = -log [H⁺] = -log 2.3 × 10⁻³ = 2.6
