If water is formed from `H^(+)` ions and `OH^(-)` the heat of formation of water is :

Options

A. `13.7Kcal`
B. 13.7 Kcal
C. `-63.4Kcal`
D. More data required

Answer

To determine the heat of formation of water from \( H^+ \) ions and \( OH^- \) ions, we can follow these steps:

### Step 1: Understand the Reaction
The reaction we are considering is the formation of water from hydrogen ions and hydroxide ions:
\[ H^+ + OH^- \rightarrow H_2O \]

### Step 2: Identify the Type of Reaction
This reaction is a neutralization reaction, where an acid (providing \( H^+ \)) reacts with a base (providing \( OH^- \)) to produce water and a salt.

### Step 3: Relate Heat of Neutralization to Heat of Formation
The heat released during this neutralization reaction is known as the heat of neutralization. For strong acids and bases, the heat of neutralization is equal to the heat of formation of water.

### Step 4: Use Known Values
From standard thermochemical data, the heat of neutralization for the reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) is approximately:
\[ \Delta H_{neutralization} = -13.6 \text{ kcal/mol} \]
This value represents the energy released when one mole of water is formed from the neutralization of \( H^+ \) and \( OH^- \).

### Step 5: Conclusion
Since the heat of neutralization is equal to the heat of formation of water, we can conclude that:
\[ \Delta H_{formation \, of \, water} = -13.6 \text{ kcal/mol} \]

Thus, the heat of formation of water is approximately:
\[ \boxed{-13.6 \text{ kcal/mol}} \]