Interpretation: The significance of using physical state (solid, liquid, gas or aqueous) of each substance in thermo-chemical reaction has to be explained.
At constant pressure, the exchange of heat between the system and surroundings is called as Enthalpy and its state function.
Enthalpy can be given by the formula,
For a reaction, enthalpy can either be positive or negative depending on the process.
The study of heat that is related with chemical reaction is called as Thermochemistry and their reactions are called as thermo-chemical reactions.