Question

Pure Benzene (C6H6) has a melting point of 5.5 degrees C. Delta Hof fusion for benzene is 9.87 kj/mol; specific heat for liquidbenzene is 1.63 J/g X degrees). A. Calculate the number of joules required to melt 57.4 g ofbenzene at 5.5 degrees C. B. Calculate the number of joules required to raise the temperatureof 57.4 g of liquid benzene from 5.5 degrees C. to 45.0 degreesC.

Answer 1

mP of benzene = 5.5 c

DHfus of benzene = 9.87 kj/mol

specific heat for liquidbenzene = 1.63 J/g.c

A. heat required to melt = n*DHfus

              = (57.4/78)*9.87

              = 7.26 kj

B. heat required to heat = n*DHfus + mass of C6H6*Specific heat of C6H6*DT

      = (57.4/78)*9.87 + 57.4 *1.63*10^-3*(45-5.5)

   = 10.95 kj