How much heat is involved in changing 88.2 g S from 111 degrees celsius to 119 degrees celsius?

Question

10th grade heat/joules/chem problem. endothermic chemistry problem

Answer 1

88.2 g S x 1 mole S/32.1 g = 2.748 moles S

The melting point of S is 115ºC, so in this problem you have a phase change, from solid S to liquid S. For this you need to know the ∆Hfusion, which is 1.7 kJ/mole. You also need to know the specific heat for S, which is 22.8 J/mol/deg. But we don't know the specific heat for liquid S. So the problem can't be completed.

Heat to change 88.2 g S from 111º to 115º = mC∆T = (2.748 mole)(22.8 J/mol/deg)(4 deg) = 251 J

Heat to melt 88.2 g S at 115º = m∆Hfusion = (2.748 mol)(1.7 kJ/mol) = 4.672 kJ = 4672 J

Then you need to know the C for liquid S to find the heat needed to raise 2.748 moles of liquid S from 115º to 119º. You'd then add that to the previous heats calculated to get the final answer.