HA is a weak acid and BOH is a weak base. For which of the following salts the extent of hydrolysis is independent of the salt in its aqueous solution

Options

A. NaA
B. NaB
C. BCl
D. BA

Answer

To solve the question regarding the extent of hydrolysis of salts formed from weak acids and weak bases, we can follow these steps:

### Step 1: Understand the Concept of Hydrolysis
Hydrolysis is the reaction of a salt with water to produce an acidic or basic solution. The extent of hydrolysis depends on the nature of the salt, specifically the strength of the acid and base from which it is derived.

**Hint:** Remember that hydrolysis occurs when a salt dissolves in water and interacts with it.

### Step 2: Identify the Types of Salts
In this case, we have a salt formed from a weak acid (HA) and a weak base (BOH). The general reaction for the formation of the salt BA from the weak acid and weak base can be written as:
\[ \text{HA} + \text{BOH} \rightarrow \text{BA} + \text{H}_2\text{O} \]

**Hint:** Recognize that the salt BA is formed from the conjugate base of the weak acid and the conjugate acid of the weak base.

### Step 3: Determine the Hydrolysis Constant
The hydrolysis constant (Kh) for the salt can be expressed as:
\[ K_h = \frac{K_w}{K_a \cdot K_b} \]
where:
- \( K_w \) is the ion product of water,
- \( K_a \) is the dissociation constant of the weak acid,
- \( K_b \) is the dissociation constant of the weak base.

**Hint:** The hydrolysis constant is crucial in determining the extent of hydrolysis.

### Step 4: Analyze the Options
For the extent of hydrolysis to be independent of the salt concentration, the salt must be such that the hydrolysis constant remains constant regardless of concentration. This typically occurs when both the acid and base are weak, leading to a balanced hydrolysis reaction.

**Hint:** Look for salts that are derived from both weak acids and weak bases, as they will exhibit this property.

### Step 5: Conclusion
Based on the analysis, the extent of hydrolysis for salts formed from weak acids and weak bases is independent of the concentration of the salt in solution. Therefore, the correct answer is option D.

**Final Answer:** Option D is correct.