What is enthalpy of a reaction? Explain the standard enthalpy of a reaction.

Explanation

Enthalpy (H) : "Enthalpy is the amount of heat exchanged by a system with its surroundings at constant pressure and temperature.
The energy change taking place at constant pressure and at a constant temperature is called enthalpy change `(triangleH).`
Mathematically, `triangleH=triangleU+P. triangleV." When "triangleU`= Internal energy change.
Enthalpy is state function. Thus, the magnitude of enthalpy change depends only upon the enthalpies in the initial and the final states.
`triangleH= [H_("Products")- H_("reactants")]`
For gaseous reactions, `triangleH=triangleU+trianglenRT`