Question

Calculate the amount of heat needed to melt 91.5g of solid benzene ( C6H6 ) and bring it to a temperature of 60.6°C . Round your answer to 3 significant digits. Also, be sure your answer contains a unit symbol.

Answer 1

Since here no initial temperature is given, lets start this problem to begin at 5.49°C: because the melting point of benzene is 5.49 degrees.

The heat of fusion = 9.87 kj/mol

heat capacity = 1.63 J /gK

T2= 60.6°C

melting the solid:
(91.5 g C6H6) / (78.11236 g C6H6/mol) x (9.87 kJ/mol) = 11.56 kJ

heating the liquid:
(1.63 J/gK) x (91.5 g) x (60.6°C °C - 5.49°C) = 8219.4 J = 8.219 kJ

total:
11.56 kJ + 8.219 kJ

= 19.779 KJ

Or 19.8 KJ

Hence the amount of heat needed to melt 91.5g of solid benzene ( C6H6 ) and bring it to a temperature of 60.6°C is 19.8 KJ.