The value of `DeltaH_(O-H)` is `109 kcal mol^(-1)`. Then formation of one mole of water in gaseous state from `H(g)` and `O(g)` is accompanied by

Options

A. Release of `218 kcal` of enegry
B. Release of `109 kcal` of enegry
C. Absorption of `218 kcal` of enegry
D. Unpredictable

Explanation

To solve the problem, we need to analyze the formation of one mole of water (H₂O) from its constituent elements, hydrogen (H) and oxygen (O), and understand the energy changes involved in this process.

### Step-by-Step Solution:

1. **Understanding the Bonds in Water**:
Water (H₂O) consists of two O-H bonds. Therefore, when we talk about the heat of formation related to water, we need to consider the energy associated with forming these two bonds.

2. **Given Data**:
The bond dissociation energy for the O-H bond is given as ΔH_(O-H) = 109 kcal/mol. Since there are two O-H bonds in one molecule of water, the total energy associated with the formation of these bonds will be:
\[ \text{Total energy for 2 O-H bonds} = 2 \times 109 \text{ kcal/mol} = 218 \text{ kcal/mol} \]

3. **Energy Change During Formation**:
The formation of water from hydrogen and oxygen can be represented by the reaction:
\[ \text{H}_2(g) + \frac{1}{2} \text{O}_2(g) \rightarrow \text{H}_2\text{O}(g) \]
In this reaction, bonds in the reactants (H-H and O=O) must be broken, which requires energy (endothermic process). The formation of new bonds in water releases energy (exothermic process).

4. **Net Energy Change**:
Since the formation of the O-H bonds releases energy, we denote this energy release with a negative sign. Thus, the overall energy change when forming one mole of water from its elements is:
\[ \Delta H = -218 \text{ kcal/mol} \]

5. **Conclusion**:
Therefore, the formation of one mole of water in the gaseous state from hydrogen and oxygen is accompanied by the release of 218 kcal of energy.

### Final Answer:
The formation of one mole of water in gaseous state from H(g) and O(g) is accompanied by the release of **218 kcal of energy**.

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