Which is the best definition of ''heat of neutralization''

Options

A. The heat set free when one gram molecule of a base is neutralized by one gram molecule of an acid in dilute solution at a stated temperature
B. The heat absorbed when one gram molecule of an acid is neutralized by one gram molecule of a base in dilute solution at a stated temperature
C. The heat set free or absorbed when one gram atom of an acid is neutralized by one gram atom of a base at a stated temperature
D. The heat set free when one gram equivalent of an acid is neutralized by one gram equivalent of a base in dilute solution at a stated temperature

Explanation

**Step-by-Step Text Solution:**

1. **Understanding the Concept**: The heat of neutralization refers to the amount of heat released or absorbed when an acid reacts with a base to form salt and water. This reaction typically involves the combination of hydrogen ions (H⁺) from the acid and hydroxide ions (OH⁻) from the base to form water (H₂O).

2. **Definition**: The best definition of heat of neutralization is the heat change (ΔH) that occurs when one gram equivalent of an acid reacts with one gram equivalent of a base in dilute solution at a constant temperature.

3. **Quantitative Aspect**: The heat of neutralization is usually expressed in terms of energy per gram equivalent. For example, the standard heat of neutralization for strong acids and bases is approximately -57.3 kJ per gram equivalent. This negative sign indicates that the reaction is exothermic, meaning heat is released during the process.

4. **Clarification on Terminology**: It is important to note that the term "gram equivalent" refers to the amount of substance that can donate or accept one mole of hydrogen ions (H⁺) in a reaction. Therefore, when discussing heat of neutralization, we are specifically referring to the heat change associated with the reaction of equivalent amounts of acid and base.

5. **Conclusion**: Thus, the heat of neutralization can be summarized as the heat released when one gram equivalent of an acid is neutralized by one gram equivalent of a base in a dilute solution at a constant temperature.

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