Enthalpy Change Calculator
Work out the enthalpy change of a reaction from calorimetry data. Enter your experimental measurements to find ΔH in kJ/mol and see whether the reaction is exothermic or endothermic.
Calculate Your Enthalpy Change
Enter the mass, specific heat capacity, temperature change, and moles of limiting reactant from your experiment to calculate the heat released or absorbed and the molar enthalpy change.
Calorimetry Data
Enter your experimental measurements
Reaction Evaluation
Calculated heat and enthalpy change
Common Specific Heat Capacities
Typical specific heat capacity values used in calorimetry calculations.
| Substance | Typical Use | Specific Heat Capacity |
|---|---|---|
| Water / dilute aqueous solution | Neutralisation, displacement reactions | 4.18 J/g°C |
| Ethanol | Combustion experiments | 2.44 J/g°C |
| Aluminium | Calorimeter material | 0.90 J/g°C |
| Copper | Calorimeter material | 0.39 J/g°C |
| Glass | Calorimeter vessel | 0.84 J/g°C |
Enthalpy Change FAQ
Everything you need to know about calculating and interpreting enthalpy change.
Enthalpy change (ΔH) is the amount of heat energy absorbed or released by a chemical reaction at constant pressure. It is usually measured in kilojoules per mole (kJ/mol) of the limiting reactant.
The heat released or absorbed is calculated using q = m × c × ΔT, where m is the mass of the solution, c is its specific heat capacity, and ΔT is the temperature change. The molar enthalpy change is then ΔH = −q ÷ n, where n is the number of moles of the limiting reactant.
An exothermic reaction releases heat to its surroundings, causing the temperature to rise and giving a negative ΔH value. An endothermic reaction absorbs heat from its surroundings, causing the temperature to fall and giving a positive ΔH value.
By convention, ΔH represents the enthalpy of the reacting system. When a reaction releases heat to the surroundings, the system loses energy, so the enthalpy change is recorded as negative, even though the temperature of the surroundings increases.