The standard enthalpy of formation is defined as the change in enthalpy when one mole of a substance in the standard state (1 atm of pressure and temperature of 298.15 K) is formed from its pure elements under the same conditions.
Answer : It is called as standard heat of formation.
Explanation :
Enthalpy of formation : The enthalpy of change when one mole of a pure compound is formed from its elements is called the enthalpy of formation. It is denoted as, [tex]\Delta H_f[/tex].
Standard heat of formation : When the reacting elements and the product formed are all in their standard state at [tex]25^oC[/tex], the enthalpy change accompanying the chemical reaction is called the standard enthalpy of formation or standard heat of formation. It is denoted as, [tex]\Delta H_f^o[/tex].
Hence, it is called as standard heat of formation.
