The absolute enthalpy of neutralization of the reaction,
`MgO(s)+2HCl(aq.)+H_(2)O(l)` will be

Options

A. Greater than `-57.33KJmol^(-1)`
B. Less than `-57.33KJmol^(-1)`
C. `-57.33KJmol^(-1)`
D. `57.33KJmol^(-1)`

Explanation

To find the absolute enthalpy of neutralization for the reaction involving magnesium oxide (MgO) and hydrochloric acid (HCl), we will follow these steps:

### Step 1: Write the balanced chemical equation for the reaction.
The reaction between magnesium oxide and hydrochloric acid can be represented as:
\[ \text{MgO(s)} + 2 \text{HCl(aq)} \rightarrow \text{MgCl}_2\text{(aq)} + \text{H}_2\text{O(l)} \]

### Step 2: Identify the nature of the reactants.
In this reaction, MgO is a metal oxide that acts as a weak base, while HCl is a strong acid. The neutralization reaction will produce magnesium chloride (MgCl2) and water.

### Step 3: Understand the enthalpy of neutralization.
The standard enthalpy change of neutralization for strong acid-strong base reactions is typically around \(-57.33 \, \text{kJ/mol}\). However, since MgO is a weak base, the enthalpy change will be less exothermic due to the additional energy required to dissociate the weak base.

### Step 4: Determine the enthalpy of neutralization for the weak base.
When a weak base reacts with a strong acid, the enthalpy of neutralization is lower than that of strong acid-strong base reactions. Therefore, we can conclude that the enthalpy change for this reaction will be less than \(-57.33 \, \text{kJ/mol}\).

### Step 5: Conclude the absolute enthalpy of neutralization.
Since the enthalpy of neutralization for a weak base with a strong acid is less than \(-57.33 \, \text{kJ/mol}\), we can state that the absolute enthalpy of neutralization for this reaction will be approximately:
\[ \Delta H < -57.33 \, \text{kJ/mol} \]

### Final Answer:
The absolute enthalpy of neutralization of the reaction \( \text{MgO(s)} + 2 \text{HCl(aq)} \rightarrow \text{MgCl}_2\text{(aq)} + \text{H}_2\text{O(l)} \) will be less than \(-57.33 \, \text{kJ/mol}\).

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