Question

The heat of formation of \( \text{SO}_2(g) \) is given by: \[ S(g) + \frac{3}{2} O_2(g) \rightarrow SO_3(g) + 2x \, \text{kcal} \] \[ SO_2(g) + \frac{1}{2} O_2(g) \rightarrow SO_3(g) + y \, \text{kcal} \]

• A. \( \frac{2x}{y} \, \text{kcal} \)
• B. \( x + y \, \text{kcal} \)
• C. \( y - 2x \, \text{kcal} \)
• D. \( 2x + y \, \text{kcal} \)

Hint:

The heat of formation is calculated using Hess's law, which involves adding or subtracting the enthalpy changes of the given reactions.

Answer 1

The Correct Option is C

The heat of formation of \( \text{SO}_2 \) is the heat change when 1 mole of \( \text{SO}_2(g) \) is formed from its elements in their standard states. 
By using the given reactions, the heat of formation is found to be \( y - 2x \).
Final Answer: \( y - 2x \, \text{kcal} \).