Question

Use the equations with the enthalpy information given below to calculate the ÄH° for the reaction:
S(s) + O2(g) --> SO2(g)

S(s) + 3/2 O2(g) --> SO3(g)
ÄH° = -395kJ

2 SO2(g) + O2(g) --> 2 SO3(g)
ÄH° = -198.2 kJ

Answer 1

1) S(s) + 3/2 O2(g) --> SO3(g)
ÄH° = -395kJ

2) 2SO2(g) + O2(g) --> 2 SO3(g)
ÄH° = -198.2 kJ

Multiply equation 1 by 2 and add to the reverse of equation 2. delta H values are multiplied by any multipliers and delta H values change their sign when the reaction is reversed.
When you finish you will have the right equation EXCEPT it will be just twice what you want; therefore, divide everything by 2 including the delta H value.

Answer 2

How much heat is evolved when 320 g of SO2 is burned according to the chemical equation shown below?