Question

The heat of vaporization of benzene c₆h₆ , is 30.8 kJ/mol at its boiling point of 80.1 degrees Celsius. How much energy in the form of heat is required to vaporize 128 g benzene at its boiling point?

Answer 1

STEP 1 - convert the mass of benezene in moles of benzene.

Moles of benzene = mass of benzene / molar mass of benezene

= 128 g/ 78 gmol^-1

= 1.64 mol

STEP 2 multiply this mole number to heat of vaporization

Heat required to vaporize 128g benzene

= (1.64 mol)× ( 30.8 kj/mol)

= 50.5 kj (Answer)