Calculate the∆H_rxnfor

Given the following set of reactions:

• A. -494.4 kJ
• B. -692.8 kJ
• C. 494.4 kJ
• D. -346.4 kJ

Answer: (B)

Verified step by step guidance

1. Identify the target reaction: S(s) + (3/2)O2(g) -> SO3(g). We need to find the enthalpy change (∆Hrxn) for this reaction.
2. Examine the given reactions and their enthalpy changes: 1) (1/2)S(s) + (1/2)O2(g) -> (1/2)SO2(g), ∆H = -296.8 kJ; 2) 2SO3(g) -> 2SO2(g) + O2(g), ∆H = 198.4 kJ.
3. Adjust the first reaction to match the formation of SO2 from S and O2: Multiply the entire reaction by 2 to get S(s) + O2(g) -> SO2(g), and multiply the enthalpy change by 2, resulting in ∆H = -593.6 kJ.
4. Adjust the second reaction to match the decomposition of SO3: Reverse the reaction to get 2SO2(g) + O2(g) -> 2SO3(g), and change the sign of the enthalpy change, resulting in ∆H = -198.4 kJ.
5. Combine the adjusted reactions: Add the adjusted reactions to get the target reaction S(s) + (3/2)O2(g) -> SO3(g). Sum the enthalpy changes: ∆H = -593.6 kJ + (-198.4 kJ).