How To: Measure melting points in the chemistry lab

The Interactive Lab Primer (ILP) has been developed as part of the Royal Society of Chemistry Teacher Fellowship Scheme, one of the themes of the Chemistry for Our Future program, and initiative which aims to secure a strong and sustainable future for the chemical sciences in higher education. The aim of the ILP is to address the diverse range of experience and skills students bring with them to a university by offering a resource to support their transition from school to the university chemistry laboratory. The ILP is quite simply a visual guide to common laboratory techniques.

This video tutorial will teach you how to measure melting points in the chemistry lab. The measurement of melting points is a relatively straightforward procedure that is carried out to determine the purity of a compound or to assist with its identification. A pure compound will melt over a relatively narrow temperature range, impurities both lowering temperature and widening the range over which it melts. The apparatus used to measure melting points can be simple oil baths to 'hot-stage' apparatus where the melting process is observed with the aid of a microscope. In each case the range of temperatures a compound melts is recorded and compared with known data.

Always make yourself aware of the hazards associated with the chemicals involved in a practical before you even start. If you ever come across a chemical you do not know the hazard of you must assume that is very hazardous until you find otherwise.