Question

Calculate the enthalpy change for the change \( \text{S}_8(g) \rightarrow \text{S}_g(g) \), given that: \[ H_2S_2(g) \rightarrow 2H(g) + 2S(g), \quad \Delta H = 239.0 \, \text{kcal/mol} \] \[ H_2S(g) \rightarrow 2H(g) + S(g), \quad \Delta H = 175.0 \, \text{kcal/mol} \]

• A. \( +512.0 \, \text{kcal} \)
• B. \( -512.0 \, \text{kcal} \)
• C. \( 508.0 \, \text{kcal} \)
• D. \( -508.0 \, \text{kcal} \)

Hint:

For reactions involving multiple steps, the total enthalpy change is the sum of the enthalpy changes for each individual step.

Answer 1

The Correct Option is A

Step 1: The enthalpy change for the reaction is the sum of the enthalpy changes of the intermediate reactions.
Step 2: Add the provided enthalpy changes to get the total enthalpy change for the transformation. \[ \Delta H = 239.0 \, \text{kcal/mol} + 175.0 \, \text{kcal/mol} = 512.0 \, \text{kcal/mol}. \]
Final Answer: \[ \boxed{+512.0 \, \text{kcal}} \]