Acidic strength of `CH_3 COOH` in presence of `CH_3 `COONa :-

Options

A. increases
B. decreases
C. sometime increases or sometime decreases
D. remain unchanged

Answer

To determine the effect of sodium acetate (CH₃COONa) on the acidic strength of acetic acid (CH₃COOH), we can follow these steps:

### Step 1: Understand the components
Acetic acid (CH₃COOH) is a weak acid that partially dissociates in solution:
\[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \]

When sodium acetate (CH₃COONa) is added to the solution, it dissociates completely into sodium ions (Na⁺) and acetate ions (CH₃COO⁻):
\[ \text{CH}_3\text{COONa} \rightarrow \text{CH}_3\text{COO}^- + \text{Na}^+ \]

### Step 2: Analyze the effect of acetate ions
The addition of sodium acetate increases the concentration of acetate ions (CH₃COO⁻) in the solution. According to Le Chatelier's principle, if we increase the concentration of one of the products (in this case, CH₃COO⁻), the equilibrium of the dissociation of acetic acid will shift to the left to counteract this change:
\[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \]

### Step 3: Determine the effect on H⁺ concentration
As the equilibrium shifts to the left, the concentration of H⁺ ions decreases. Since the acidic strength of a solution is directly related to the concentration of H⁺ ions, a decrease in H⁺ concentration means a decrease in acidic strength.

### Step 4: Conclusion
Thus, the presence of sodium acetate decreases the acidic strength of acetic acid. Therefore, the correct answer is that the acidic strength of CH₃COOH in the presence of CH₃COONa decreases.

### Summary of Steps:
1. Identify the components: acetic acid and sodium acetate.
2. Understand the dissociation of acetic acid and the complete dissociation of sodium acetate.
3. Apply Le Chatelier's principle to analyze the shift in equilibrium.
4. Conclude that the increase in acetate ions leads to a decrease in H⁺ concentration, thus decreasing the acidic strength.