Thermal analysis, also known as thermoanalysis, is a group of methods for detecting and studying physical and chemical changes in substances heated at a standard rate through a temperature range. It is sometimes used for chemical analysis.
In thermogravimetric analysis (TGA), the sample is weighed in a thermobalance – a sensitive balance with the sample pan inside a furnace – and its weight is plotted against temperature. Weight loss is due to giving off gases or vapors; weight gain to reaction with the atmosphere. In differential thermal analysis (DTA), the sample is heated simultaneously with an inert reference substance (usually aluminum oxide), and the temperature difference between them is plotted against temperature. This deviates from zero in one direction when an exothermic reaction occurs. and in the other direction when an endothermic reaction occurs. See also thermochemistry.