Question

1. What is the heat (q) needed by water with molar heat of vaporization of 40.7 kJ if it is 50.0 g in mass and boils at 100°C? Note that the molar mass of water is 18.0 g/mol.

2. How will you compare it with the heat needed by alcohol with molar heat of vaporization 44.0 kJ at 35.0 g and boils at 82.5°C? Note that the molar mass of isopropyl alcohol is 60.1 g/mol.

Answer 1

1.Let molar heat of vaporization be ∆H_vap

∆H_vap = 40.7 kJ

2.Moles of $H2O = \frac{50}{18}=2.78 moles$

Heat = $40.7 × 2.78=113.146 kJ$