Beckrnann Freezing Point Method: Easy Arresting of Supercooling In rhe Firvkmar~ntrtwiny point m c t h d a large s u p e n w l i ~ ~\ >l I: D ( ' , i, g r w r n l l ~obserwl F'm the p w ~ i dl . ~iwn~inatism ,Itn.: shuuld t1.11 Iw rv rhnn t1.:3" Il:"(' Fitit it i;diflirult tu check rhe ;t~pcrcwXngwthin thii limit hi either \.iyorcn~istirring ilw c)\trrn or scratching the sides of the freezing tube. A prompt disturbance of the metastable equilibrium with consequent arresting of the s u ~ e r e a o l i nand ~ subsequent shooting.up of the temperature can, however, be affected bv the addition of solvent crystals. A simple procedure with a slightly modified Beckmann freezing point set-up is described to prevent the troublesome large supercooling. In the Beckmann freezing point set-up an additional hole is made in the cork carrying the Beckmann thermometer and stirrer. A small amount of the solvent is taken in the semimiera tube. A clean, thin and straight nickel wire is inserted into the solvent in the semimicro tube. The tube is then placed in freezing mixture to freeze the solvent. During the course of the experiment when supercooling is observed, this thin nickel wire, with minute crystals adhering to it, is rapidly taken out from the semimicro tube, inserted momentarily into the system in the freezing tube through the additional hale and withdrawn. This method of introducing the minute solvent speed crystals prevents supercooling promptly without appreciably altering the concentration of the system. ~
V. 0. Chidambaram College Tutiwrin-628003. India
42 1 Journal of Chemical Education
