The enthalpy of neutralization is about 57.3 kJ for the pair

Options

A. `HCl and NH_(4)OH`
B. `NH_(4)OH and HNO_(3)`
C. `HCl and NaOH`
D. `CH_(3)COOH and NaOH`

Answer

To solve the problem regarding the enthalpy of neutralization, we need to identify the correct pair of acid and base that corresponds to the given enthalpy of 57.3 kJ. The enthalpy of neutralization is typically associated with the reaction between a strong acid and a strong base.

### Step-by-Step Solution:

1. **Understand the Concept of Enthalpy of Neutralization**:
The enthalpy of neutralization is the heat change that occurs when an acid reacts with a base to form water and a salt. For strong acids and strong bases, this value is approximately -57.3 kJ/mol.

2. **Identify the Options Given**:
We have four pairs of acid and base to analyze:
- Option 1: HCl and NH4OH
- Option 2: NH4OH and HNO3
- Option 3: HCl and NaOH
- Option 4: CH3COOH and NaOH

3. **Analyze Each Pair**:
- **Option 1 (HCl and NH4OH)**: HCl is a strong acid, but NH4OH (ammonium hydroxide) is a weak base. This pair will not yield the standard enthalpy of neutralization.

- **Option 2 (NH4OH and HNO3)**: HNO3 is a strong acid, but NH4OH is still a weak base. This pair will also not yield the standard enthalpy of neutralization.

- **Option 3 (HCl and NaOH)**: Both HCl (strong acid) and NaOH (strong base) are strong substances. This pair is expected to yield the standard enthalpy of neutralization of -57.3 kJ/mol.

- **Option 4 (CH3COOH and NaOH)**: CH3COOH (acetic acid) is a weak acid, while NaOH is a strong base. This pair will not yield the standard enthalpy of neutralization.

4. **Conclusion**:
The correct pair that gives the enthalpy of neutralization of about -57.3 kJ is **Option 3: HCl and NaOH**.

### Final Answer:
The correct pair of acid and base for which the enthalpy of neutralization is about 57.3 kJ is **HCl and NaOH**.

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