For which one of the following equations is `Delta H_(react)^(@)`equal to `DeltaH_(r)^(@)` for the product?

Options

A. `N_(2)(g) + O_(3)(g) rightarrow N_(2)O_(3)(g)`
B. `CH_(4)(g) + 2CI_(2)(g) rightarrow CH_(2)CI_(2)(I) + 2HCI(g)`
C. `Xe(g) + 2F_(2)(g) rightarrow XeF_(4)(g)`
D. `2CO(g) + O_(2)g) rightarrow 2CO_(2)(g)`

Answer

To determine for which equation the standard enthalpy change of reaction (ΔH_react^(@)) is equal to the standard enthalpy change of formation (ΔH_f^(@)) for the product, we can analyze the equations based on the definition of enthalpy of formation.

### Step-by-Step Solution:

1. **Understand the Definitions**:
- The standard enthalpy change of formation (ΔH_f^(@)) of a compound is defined as the enthalpy change when 1 mole of the compound is formed from its elements in their standard states.
- The standard enthalpy change of reaction (ΔH_react^(@)) is the enthalpy change for a given reaction.

2. **Identify the Equations**:
- We need to analyze the provided equations to see if any of them represent the formation of a product from its elements in their standard states.

3. **Analyze Each Equation**:
- **Equation 1**: N2 + O2 → N2O3
- This reaction does not represent the formation of N2O3 from its elements in their standard states because O3 is not in its elemental form.
- **Equation 2**: CH4 + 2 HCl → CH2Cl2
- This does not represent the formation of CH2Cl2 from its elements, as CH4 is not in its elemental form.
- **Equation 3**: Xe + 2 F2 → XeF4
- This equation represents the formation of XeF4 from its elements (Xe and F2) in their standard states. Therefore, ΔH_react^(@) = ΔH_f^(@) for XeF4.
- **Equation 4**: 2 CO + O2 → 2 CO2
- This does not represent the formation of CO2 from its elements, as CO is not in its elemental form.

4. **Conclusion**:
- The only equation where ΔH_react^(@) is equal to ΔH_f^(@) for the product is the third equation: **Xe + 2 F2 → XeF4**.

### Final Answer:
The equation for which ΔH_react^(@) is equal to ΔH_f^(@) for the product is **Xe + 2 F2 → XeF4**.