Explain the state function 'enthalpy, H'. What is the relationship between `DeltaU and DeltaH`?

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)`.
Enthalpy is state function. Thus, the magnitude of enthalpy charge depends only upon the enthalpies in the initial and the final states.
`triangleH=[H_("Products")-H_("Reactants")]`
For gaseous reactions, `triangleH=triangleU+trianglenRT`