The `pH` of a dilute solution of acetic acid was found to be `4.3`. The addition of a small crystal of sodium acetate will cause `pH` to

Options

A. (a) Become less than `4.3`
B. (b) Become more than `4.3`
C. (c) Remain equal to `4.3`
D. (d) Unpredictable

Explanation

To solve the question regarding the effect of adding sodium acetate to a dilute solution of acetic acid on the pH, we can follow these steps:

### Step 1: Understand the Components
- We have a dilute solution of acetic acid (CH₃COOH) with a pH of 4.3.
- Acetic acid dissociates into acetate ions (CH₃COO⁻) and hydrogen ions (H⁺):
\[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \]

### Step 2: Identify the Effect of Sodium Acetate
- Sodium acetate (CH₃COONa) dissociates in solution to give acetate ions and sodium ions:
\[ \text{CH}_3\text{COONa} \rightarrow \text{CH}_3\text{COO}^- + \text{Na}^+ \]
- Adding sodium acetate increases the concentration of acetate ions (CH₃COO⁻) in the solution.

### Step 3: Apply the Common Ion Effect
- The addition of acetate ions (common ion) will shift the equilibrium of the acetic acid dissociation reaction to the left (backward direction) according to Le Chatelier's principle:
\[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \]
- This shift reduces the concentration of hydrogen ions (H⁺) in the solution.

### Step 4: Analyze the Change in pH
- Since pH is inversely related to the concentration of hydrogen ions (H⁺), a decrease in H⁺ concentration will lead to an increase in pH.
- Therefore, the pH of the solution after adding sodium acetate will be greater than 4.3.

### Conclusion
- The addition of a small crystal of sodium acetate will cause the pH to **increase** (be greater than 4.3).

### Final Answer
The pH will be more than 4.3.

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