Power delivered by coil, P = i2R = 5.22 x 12 = 324.48 W
rate of evapoartion of liquid = 21 mg/s = 21 x 10-6 kg/s
heat gained by liquid per second = (21 x 10-6) L (where L is the latent heat of vaporization)
324.48 = (21 x 10-6) L
L = 15.45 x 106 J / kg