Chemistry Help?

Question

CuSO4(s)--->Cu2+ with 2+ being on the top(aq)+SO2-4 with 2- on top while 4 on bottom(aq)

She placed 0.8 g of CuSO4(s) in a calorimeter iwth 43 g of water at an initial temperature of 18.3 degrees celcius. As the CuSO4(s) disslved in the water, the temperature rose to 20.2 degrees celcius.What value of enthalpy H can Teresa obtain from her data

How much heat will be tranferred when 0.54 mol sulfur reacts with 0.75 mol oxygen according to the following equation
2S(s)+3O2(g)--->2SO3(g) enthalpy change is -790 kJ
How many moles of SO3 will be produced?

I am really stuck on these two problems, would it be possible if you people could help me out on how to figure out this problem

Answer 1

2)since two mol of s always react wid 3 mol of O2 therefore
1mol of s===>3/2mol of O2
0.54 mol of s====>.81mol of O2
therefore s is limiting agent
we solve eq using O2
since
3 mol of O2=====>2 mol of So3
therefore 0.75mol====>.5 mol of SO3
when 2 mol of SO3 is produced Ho=-790 kj
2mol SO3====>790 kj
.5 mol =====>365 kj