General Chemistry Homework Question

Question

Suppose that 132.0 J of heat energy is required to completely vaporize 3.1 g of a pure liquid. If the molar mass of the liquid is 40.17 g/mol, what is the molar enthalpy of vaporization of the liquid?

Answer 1

How many moles of liquid are there?

3.1 g x 1 mole/40.17 g = 0.07717 moles of liquid

molar enthalpy of vaporization = 132.0 J/0.07717 moles = 1711 J/mole = 1700 J/mole (2 sig. figs.)