Can someone help me with enthalpy of heat?

Question

Ethanol, C2H5OH, melts at -114°C and boils at 78°C. The enthalpy of fusion of ethanol is 5.02 kJ/mol, and its enthalpy of vaporization is 38.56 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g·K and 2.3 J/g·K, respectively. How much heat is required to convert 78.0 g of ethanol at -127°C to the vapor phase at 78°C? The answer should be in kJ.

Answer 1

Think about the process in stages.

First, you have to warm the solid ethanol to its melting point:

q = mcDT = 78.0g(0.97j/gK)(13K)= ___ J

Then, you have to melt the solid at -114 C:

q = 5.02 kJ/mol (78g/46 g/mol)= ___ kJ

THen, you have to warm the liquid to its boiling point:

q = 78 X 2.3 X 182 = ____ J

Then you have to vaporize the liquid

q = 38.56 X 78/46 = ____ kJ.

Finally, convert all the answers to kJ and add them up.

(Be sure and check my numbers against your problem as you do the calculations.)