The use of cryoscopy method for determination of freezing temperature of waters having different content of deuterium

摘要

Using the method of cryoscopy we determined the freezing temperature of light water with D/H= 4.2 ppm, O-18/O-16 = 910 ppm. It was found that light water freezes at the above zero temperature (0.3 +/- 0.1A degrees C) irrespective of cooling rate. It is shown that light water begins to freeze only at an overcooled metastable state. Under conditions of experiment the nucleation and growth of dendrite crystals of ice depends on the cooling rate and starts at the temperature -5.3; -8.8; -9.8 +/- 0.1A degrees C at the average cooling rate respectively 0.2; 0.3; 0.5A degrees C center dot min(-1). It is shown than in usual water the growth of dendrite ice crystals starts at minus temperature (-6.4;-7.5; -8.8 +/- 0.1A degrees C) and increases with an increase of the average cooling rate respectively from 0.2 to 0.6A degrees C center dot min(-1). It was found that the initial freezing temperature of heavy water constituted -3.0- -4.0 +/- 0.1A degrees at the rate of its cooling 0.2-1.0A degrees C center dot min(-1). However in this case the freezing temperature of normal and heavy waters does not depend on the cooling rate and freezing of normal and heavy waters and according to reference data constitutes respectively 0.1 +/- 0.1 and 3.9 +/- 0.1A degrees C.