Question

Calculate the amount of heat needed to melt 51.8 g of solid benzene (C,H) and bring it to a temperature of 40.2 °C. Round your answer to 3 significant digits. Also, be sure your answer contains a unit symbol. do

Answer 1

Heat required(q) = n*DHfus + m*s*DT

No of mole of benzene(n) = 51.8/78 = 0.664 mol

Enthalpy of fusion of benzene(DHfus) = 9.9 kj/mol

Melting point of benzene(Tf) = 5.5 C

Mass of benzene (m) = 51.8 g

Specific heat of benzene (s) = 1.74 j/g.k

Final temperature = 40.2 c

      q = 0.664*9.9*10^3+51.8*1.74*(40.2-5.5)

       = 9.70 kj

answer: 9.70 kj