The formation of water from `H_(2)(g)` and `O_(2)(g)` is an exothermic process because :

Options

A. The chemical energy of `H_2(g) and O_(2)(g)` is mere than that of water
B. The chemical ener gy of `H_2(g) and O_(2)(g)` is less than that of water
C. The temperature of `H_2(g) and O_(2)(g)` is higher than that of water
D. The temperature of `H_2(g) and O_(2)(g)` is lower th an that of water

Answer

To determine why the formation of water from hydrogen gas (H₂) and oxygen gas (O₂) is an exothermic process, we can analyze the enthalpy change (ΔH) associated with the reaction. Here’s a step-by-step breakdown of the reasoning:

### Step 1: Understand the Reaction
The chemical reaction for the formation of water can be written as:
\[ 2H_2(g) + O_2(g) \rightarrow 2H_2O(l) \]
This reaction involves the combination of hydrogen and oxygen gases to form liquid water.

### Step 2: Define Exothermic Reaction
An exothermic reaction is one that releases heat to the surroundings. In terms of enthalpy change (ΔH), this means:
\[ \Delta H < 0 \]
This indicates that the energy of the products is less than the energy of the reactants.

### Step 3: Analyze Enthalpy Change
Enthalpy (H) is a measure of the total energy of a thermodynamic system. The change in enthalpy (ΔH) during a reaction can be expressed as:
\[ \Delta H = H_{\text{products}} - H_{\text{reactants}} \]
For the reaction to be exothermic, the enthalpy of the products (water) must be lower than that of the reactants (hydrogen and oxygen).

### Step 4: Compare Energies
In this case, the chemical energy stored in the bonds of hydrogen (H₂) and oxygen (O₂) is greater than that stored in the bonds of water (H₂O). Therefore:
\[ H_{\text{reactants}} > H_{\text{products}} \]
This means that when hydrogen and oxygen combine to form water, some of the stored energy in the reactants is released as heat, resulting in a negative ΔH.

### Step 5: Conclusion
Thus, the formation of water from hydrogen and oxygen is an exothermic process because the chemical energy of the reactants (H₂ and O₂) is greater than that of the product (H₂O). This results in a release of energy, making ΔH negative.

### Final Answer
The formation of water from H₂ and O₂ is an exothermic process because the chemical energy of H₂ and O₂ is greater than that of water.

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