A sample of a substance X that has a mass of 326.0g releases 4325.8 cal when it freezes at its freezing point. If substance X has a molar mass of 58.45g/mol, what is the molar heat of fusion for substance X?
A. 13.31 cal/mol
B.74.00 cal/mol
C. 775.6 cal/mol
D. 19054.7 cal/mol

Question

A sample of a substance X that has a mass of 326.0g  releases 4325.8 cal when  it freezes at its freezing point.  If substance X  has a molar mass of 58.45g/mol,  what is the molar heat of fusion for substance X? 
A. 13.31 cal/mol
B.74.00 cal/mol
C. 775.6 cal/mol
D. 19054.7 cal/mol

cuanchi · Answer

The molar heat of substance X will be the amount of heat released by ONE mol of substance X. 
You have the amount of substance X (m) and its molar mass (MM). You can calculate the number of mole of substance X you have (n). 

n= m/ MM

Then you have the total heat released 4325.8 cal released by "n" number of moles. 

Molar heat of fusion = 4325.8 cal / n