Dispensing Low-Melting Solids: Freezing Point Depression A common problem in chemistry laboratories is that of dispensing law-melting solids such as cyclohexanol, tert-butyl alcohol, and phenol. Although these substances melt somewhat above typical room temperatures, they are usually packaged in narrow-necked bottles ordinarilv used for liauids. Students are faced with the ~ r o b l e mof how to aet asolid out throunh the small opening. One solution, obviously, is to warm the bottle and melt the reagent, but hot platespresent fire and burn hazards and a hot water or steam bath often washes off the label.
of water do not interfere with most syntheses and test reactions, many of which are done in aqueous solution or with aqueous reagents anyway. If water does present a problem, methanol or other solute can be employed todepress the freezing point. For other low-melting solids, exact amount of solute required for a given freezing point depression can be calculated from the depression constant for the compound. The solute should be added a day or so in advance because the melting is often slow. t o more serious ones in another experiment
John W. Hill Univenity of Wisconsin River Falls, WI 54022
Volume 59
Number 8
August 1982
699
