Standard Formation Reaction

A chemical reaction in which one mole of a substance in its standard state
is made from it's elements in their standard states.

Standard State :  Pure substance in most stable thermodynamic state at a pressure of 1 bar (~ 1atm) and a fixed temperature (often chosen to be 25^oC).

Standard Enthalpy of Formation : The enthalpy change for a standard formation reaction, ΔH^o_f .

Using Standard Enthalpies of Formation:

Equivalent to turning reactants into elements then forming products from these elements.

Example:  CaCO3(s) + heat –––> CaO(s) + CO2(g)