Question

Calculate the amount of heat needed to melt

C6H6

) and bring it to a temperature of

3

significant digits. Also, be sure your answer contains a unit symbol.

Answer 1

[ Note that the amount of benzene is not mentioned, and also the temperature is not mentioned, i assumed the temperature to be 34⁰C and the amount to be 115 g , Do solve it again using your original values]

The melting point of benzene is 5.49⁰C, heat of fusion is 9.87 KJ/mol and the ehat capacity = 1.63 J/g K

Since no initial temperature is given, supposing the problem to begin at 5.49⁰C:

Melting the solid:
(115 g C₆H₆) / (78.11236 g C₆H₆/mol) x (9.87 kJ/mol) = 14.531 KJ

Heating the liquid:
(1.63 J/gK) x (115 g) x (34⁰C - 5.49⁰C) = 5344 J = 5.344 KJ

Total amount of heat needed=14.531 KJ + 5.344 KJ = 19.875 KJ = 19.9 KJ ( 3 significant figures)