The enthalpy of neutralisation of four acids HA,HB,HC and HD with NaOH are -13,-12,-11,-10 Kcal//mol. Which salt has maximum degree of hydrolysis?

Options

A. 1 M NaA
B. 1 M NaB
C. 1 M NaC
D. 1 M NaD

Answer

To determine which salt has the maximum degree of hydrolysis among the salts formed from the acids HA, HB, HC, and HD when neutralized with NaOH, we can follow these steps:

### Step 1: Understand Enthalpy of Neutralization
The enthalpy of neutralization is the heat released when one equivalent of an acid reacts with a base (in this case, NaOH). The given values for the enthalpy of neutralization for the acids are:
- HA: -13 kcal/mol
- HB: -12 kcal/mol
- HC: -11 kcal/mol
- HD: -10 kcal/mol

### Step 2: Relate Enthalpy of Neutralization to Acid Strength
The magnitude of the enthalpy of neutralization is proportional to the dissociation constant (Ka) of the acid. A higher enthalpy of neutralization indicates a stronger acid, which means it dissociates more in solution.

### Step 3: Order the Acids by Strength
Based on the enthalpy values, we can order the acids by their strength (or Ka values):
- HA > HB > HC > HD

### Step 4: Understand Degree of Hydrolysis
The degree of hydrolysis (H) of a salt is inversely related to the strength of the acid from which it is formed. The stronger the acid (higher Ka), the lower the degree of hydrolysis of the corresponding salt.

### Step 5: Determine the Order of Degree of Hydrolysis
Since the degree of hydrolysis is inversely related to the strength of the acid, we can determine the order of hydrolysis based on the order of acid strength:
- HD (weakest acid, maximum degree of hydrolysis)
- HC
- HB
- HA (strongest acid, minimum degree of hydrolysis)

### Step 6: Conclusion
Thus, the salt formed from the weakest acid (HD) will have the maximum degree of hydrolysis. Therefore, the salt formed from HD, which we can denote as NaD, will have the maximum degree of hydrolysis.

### Final Answer
The salt with the maximum degree of hydrolysis is NaD.

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