Rates of evaporation VI. The vapour pressure and rate of evaporation of potassium chloride

The vapour pressure of potassium chloride has been determined by an effusion method at 438 to 597°C and is given by log10p mm of Hg = – 11310/T+10·451; the latent heat of vaporization over this range is 51720 ± 500 cal mole-1,giving a value of 54430 + 500 cal mole-1 at 0°K. The rate of evaporation of single crystals has been determined at 399 to 515°C. The evaporation coefficient for (100), (111) faces is 0·72 ± 0·015 (independent of temperature). A crystal with (110) and (100) faces gave an evaporation coefficient of 0·63 (independent of temperature), suggesting that the evaporation coefficient for the (110) face is 0·56.