Question

"Use Hess's Law to calculate the energy change for the reaction that produces SO3.

2S(s) +20, (g) → 280, (g) 280, (g) +0, (g) → 280, (g)
ΔH = -594kJ AH =-198kJ"

Answer 1

The enthalpy change for the given reaction producing SO3 can be calculated by first finding the number of moles of SO2 from its mass, and then using this to proportionately calculate the enthalpy change based on the given ΔH for 2 moles, considering that the reaction is exothermic.

Step-by-step explanation:

To calculate the enthalpy change for the production of SO3 using Hess's Law, we need to consider the given reactions:

• 2SO2 (g) + O2 (g) → 2SO3 (g) ΔH = -198 kJ (given)
• The production of SO3 happens in a two-step process including the formation of SO2 and its subsequent reaction with O2.

Given the total mass of SO2 (58.0 g) and the molar mass of SO2 (64.07 g/mol), we can calculate the moles of SO2:

1. Moles of SO2 = Mass SO2 / Molar mass SO2 = 58.0 g / 64.07 g/mol.
2. Find the proportion of ΔH for the actual moles of SO2 since ΔH = -198 kJ is for 2 moles.

After calculating the moles, you multiply this by the enthalpy change per mole to find the total enthalpy change for the reaction, remembering that the sign of ΔH is negative because the reaction is exothermic.