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

Explanation

The enthalpy of a reaction is defined as the enthalpy change accompanying the chemical reaction when the molar quantities of reactants and products are the same as indicated in the chemical equation. It is also known as heat of reaction. It is represented by `DeltaH`.
The enthalpy change at the standard state conditions is called standard enthalpy of the reaction. It is denoted by `Delta_(r)H^(theta)`. The superscript (`theta)` represented standard state.
Standard state of a substance is its most stable state at one bar presume and 208K.