What method is used to determine heat change in a system?

Calorimetry is the method specifically designed to measure changes in heat within a system. It involves the use of a calorimeter, which is an instrument that can accurately gauge the amount of heat absorbed or released during a chemical reaction or physical change. This is essential in thermochemistry, as understanding the heat transfer during reactions helps to characterize reaction energetics and the stability of substances.

In calorimetry, processes are conducted under controlled conditions to ensure that all heat changes can be accurately measured. This allows for the calculation of enthalpy changes, which are crucial for predicting reaction behaviors and understanding thermodynamic principles.

The other methods listed, such as spectroscopy, chromatography, and electrophoresis, serve different purposes. Spectroscopy is used for analyzing light absorption and emission properties of substances, chromatography separates mixtures based on different interactions with stationary and mobile phases, and electrophoresis separates macromolecules based on their size and charge. None of these methods directly measure heat changes in a system.