Thermochemistry studies the heat associated with chemical and physical transformations. At constant pressure, the measured heat equals the enthalpy change when the process performs only pressure-volume work and the usual thermodynamic conditions are satisfied.
Because enthalpy is a state function, a reaction enthalpy can be calculated from a sum of steps with the same overall starting and final states. This is the basis of Hess's law. A calorimetric comparison must specify temperature, phase, and composition; different physical states do not define the same thermochemical transformation.
Thermochemistry is a branch of chemistry that deals with the study of heat changes that occur during chemical reactions and physical transformations. It involves the measurement and understanding of energy changes associated with various processes, particularly focusing on the heat absorbed or released during these processes. Key concepts in thermochemistry include: 1. **Enthalpy (ΔH)**: A measure of the total heat content of a system at constant pressure.
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