Enthalpy Change Calculator

Calculate the change in enthalpy (ΔH) for a chemical reaction based on the enthalpy of products and reactants.

Reaction Parameters

Enthalpy of Products (H_prod)

Enthalpy of Reactants (H_react)

Calculation Results

Enter total enthalpy of products and reactants

Overview

Enthalpy change (ΔH) represents the heat energy absorbed or released during a chemical reaction at constant pressure.

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Pro Tips

Enthalpy is usually measured in Joules (J) or kiloJoules (kJ).
Ensure both values are in the same unit.
ΔH = H(products) - H(reactants).
For exothermic reactions, products have lower enthalpy than reactants.
For endothermic reactions, products have higher enthalpy than reactants.

Fun Facts

"Negative ΔH means the reaction releases heat (exothermic), like combustion."
"Positive ΔH means the reaction absorbs heat (endothermic), like photosynthesis."
"Hess's Law states that the total enthalpy change is the same regardless of the path taken."
"The enthalpy of formation (ΔH_f) is the energy change when one mole of a compound forms from its elements."
"Standard enthalpy changes are measured at 298 K and 1 atm pressure."
"Bond breaking requires energy input, while bond formation releases energy."
"Calorimetry measures enthalpy changes by monitoring temperature changes in insulated containers."

Formula: ΔH = Hₚ - Hᵣ

Common Reaction Enthalpy Changes

Examples of exothermic and endothermic reactions

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