Heat of Formation Calculator:
Enter values of enthalpy of products, EP(J) and enthalpy of reactants, ER(J) to determine the value of Heat of Formation, HOF(J).
Heat of Formation Formula:
The heat of formation (HOF) is the change in enthalpy (heat content) when one mole of a compound is formed from its elements in their standard states under standard conditions (usually 298 K and 1 atm). This concept is a fundamental component in thermodynamics and chemistry, providing insight into the energy required or released when creating a compound from its basic elements.
Positive values of HOF indicate that the reaction is endothermic (absorbs heat), while negative values suggest that the reaction is exothermic (releases heat). The heat of formation can be used to predict reaction energetics, helping to determine if a reaction will be favorable or if additional energy input is needed.
The HOF is usually expressed in kilojoules per mole (kJ/mol), and it plays a crucial role in chemical engineering, material science, and environmental science by allowing calculations of energy flows and efficiencies. Calculating HOF accurately involves considering bond energies and the thermodynamic properties of the involved species.
Heat of Formation, HOF(J) in Joules equals the enthalpy of the products, EP(J) in Joules minus the enthalpy of the reactants, ER(J) in Joules.
Heat of Formation, HOF(J) = EP(J) – ER(J)
HOF(J) = heat of formation in Joules, J.
EP(J) = enthalpy of products in Joules, J.
ER(J) = enthalpy of reactants in Joules, J.
Heat of Formation Calculation:
1.A reaction has products with an enthalpy of 4000 J and reactants with an enthalpy of 2500 J. Calculate the heat of formation of the reaction.
Given: EP(J) = 4000J, ER(J) = 2500J.
Heat of Formation, HOF(J) = EP(J) – ER(J)
HOF(J) = 4000 – 2500
HOF(J) = 1500J.
2.A reaction’s heat of formation (HOF) is 1200 J, and the enthalpy of reactants (ER) is 3000 J. Find the enthalpy of the products (EP) of the reaction.
Given: HOF(J) = 1200J, ER(J) = 3000J.
Heat of Formation, HOF(J) = EP(J) – ER(J)
EP(J) = HOF(J) + ER(J)
EP(J) = 1200 + 3000
EP(J) = 4200J.