Question

Calculate the amount of heat needed to melt

24.9g of solid benzene (C6H6) and bring it to a temperature of

13.5°C Be sure your answer has a unit symbol and the correct number of significant digits.

Answer 1

The complete calculation of the total amount of heat is given as below:-

It is given that, mass of benzene = (m) = 24.9 g Initial temperature (TI) = 13.5°C melting point of benzene = 25°C = T2 Then dr = (T2-T) = (25-1. 5 °C or dT = 11.5 °C ork molecular weight of C6H6 = 78.11 g/mol Number of moles of C6H6 = (24.9 g ) = 0.32 moles 78.11 g/mol/ Number of moles of C6H6 = 0.32 moles -

Xl1.5k Amount of heat to reach the temperature 25°C is given by :- a, = mxcdT = mx cxd T = 0.32 moles) X118.4 57 mol-K) where, ca 118.4 Jl molik = specific heat capacity of C6H6 Then = 435.712 J @ Further amount of heat is required to melt the benzene at 25°C will be OF NL - ③ where = heat af fusion or melting of Coho or - 9.9 kJ/mol - ④

Then from equation 3 we have aa= (0.34 moles ) x 9.9 kJl mal a= 3:168 kJ = 3:168 hJ since, IK J = 1000 J Then Qua= 3168 I 0 So, the total amount of heat will be Q = a1 + ar = (435.712 +3168) J or Q=3603.712 J So, the total amount of heat will be a = 3603.712 J