Question

What is the total energy in kj lost when 10 grams of benzene is condensed at 80.1 degrees Celsius, cooled to a melting point of negative 5.1 degrees Celsius and frozen to a solid. Heat of Fusion for benzene= 128 J/g, Heat of Evaporation for benzene= 395 J/g, Specific Heat of benzene= 1.95 J/g degree Celsius

Answer 1

Ti = 80.1

Tf = -5.1

Lv = 395.0 J/g

Heatreleasedto convert gas to liquid at 80.1 oC

Q1 = m*Lv

= 10.0g *395.0 J/g

= 3950 J

Cl = 1.95 J/g.oC

Heat released to convert liquid from 80.1 oC to -5.1 oC

Q2 = m*Cl*(Ti-Tf)

= 10 g * 1.95 J/g.oC *(80.1--5.1) oC

= 1661.4 J

Lf = 128.0 J/g

Heat released to convert liquid to solid at -5.1 oC

Q3 = m*Lf

= 10.0g *128.0 J/g

= 1280 J

Total heat released = Q1 + Q2 + Q3

= 3950 J + 1661.4 J + 1280 J

= 6891.4 J

Answer: 6891.4 J