Which of the following reaction can be used to define the heat of formation of `CO_(2)(g)` ?

Options

A. C (graphite) `+O_(2)(g)to CO_(2)(g)`
B. `CH_(4)(g)+2O_(2)(g)to CO_(2)(g)+2H_(2)O(l)`
C. `CO(g)+1//2O_(2)(g)to CO_(2)(g)`
D. `C_(6)H_(6)(l)+7(1)/(2)O_(2)(g)to 6CO_(2)(g)+3H_(2)O(l)`

Answer

To determine which reaction can be used to define the heat of formation of \( CO_2(g) \), we first need to understand what the heat of formation is. The heat of formation, or enthalpy of formation (\( \Delta H_f \)), is the heat change that results when one mole of a compound is formed from its elements in their standard states.

### Step-by-Step Solution:

1. **Identify the Definition**: The heat of formation is defined as the heat change when one mole of a compound is formed from its constituent elements in their standard states.

2. **Identify the Elements for \( CO_2 \)**: The elements that make up carbon dioxide (\( CO_2 \)) are carbon (C) and oxygen (O).

3. **Standard States of Elements**:
- The standard state of carbon is graphite.
- The standard state of oxygen is \( O_2(g) \).

4. **Write the Formation Reaction**: The formation reaction for carbon dioxide can be written as:
\[ C(s) + O_2(g) \rightarrow CO_2(g) \]
This reaction shows that one mole of \( CO_2 \) is formed from one mole of solid carbon (in its standard state) and one mole of gaseous oxygen (in its standard state).

5. **Check the Options**: Now, we need to check the given options to see which one matches the formation reaction we have written. The correct reaction should only produce \( CO_2(g) \) from its elements without any other products.

6. **Conclusion**: The reaction that matches our formation reaction is the one that shows the formation of \( CO_2(g) \) from \( C(s) \) and \( O_2(g) \). Therefore, the answer is the option that corresponds to this reaction.