🔥 Enthalpy of Reaction Calculator
Determine the enthalpy of a reaction from simple calorimetry measurements: the mass and specific heat of the solution, the temperature change observed, and the moles of limiting reactant used.
What is enthalpy of reaction?
The enthalpy of reaction (ΔH) tells you how much heat a chemical reaction releases (exothermic, negative ΔH) or absorbs (endothermic, positive ΔH) per mole of reactant, at constant pressure. It’s commonly measured experimentally with a simple calorimeter.
How this calculator works
In coffee-cup calorimetry, the reaction happens in a solution, and the heat it releases or absorbs is measured indirectly from the temperature change of that solution:
q(solution) = m × c × ΔT
where m is the mass of the solution, c is its specific heat capacity, and ΔT is the temperature change. Because heat lost by the reaction is gained by the solution (and vice versa), the heat of the reaction itself is the negative of q(solution). Dividing by the moles of limiting reactant gives the molar enthalpy of reaction in kJ/mol.
- A negative ΔT (solution cooled down) means the reaction absorbed heat — it’s endothermic, giving a positive ΔH.
- A positive ΔT (solution warmed up) means the reaction released heat — it’s exothermic, giving a negative ΔH.
This calculation assumes no heat is lost to the surroundings or the calorimeter itself, which introduces some error in real experiments. This tool is for general chemistry education purposes.