Calorimetry Calculator

Work out calorimetry instantly with clear inputs, formula shown and shareable results.

About Calorimetry Calculator

A calorimeter measures enthalpy indirectly: the reaction warms a known mass of water, and Q = mcdT with c = 4.184 J/g/K recovers the heat. Dividing that heat by the moles reacted and flipping the sign gives the molar enthalpy change, since heat gained by the water was lost by the reaction.

Formulas

Heat absorbed by water

Q = m x 4.184 x dT

Molar enthalpy

dH = -Q / moles reacted

Worked example

With the default values below, Calorimetry Calculator returns Molar Enthalpy Change of -535.55. Change any input above and every figure here is recalculated in your browser.

Inputs used

Mass of water in the calorimeterminimum 0.01 g: 100 g
Temperature rise recorded: 6.4 K
Moles of reactant consumedminimum 0 mol: 0.005 mol

Results

Molar Enthalpy Change: -535.55 kJ/mol
Heat Absorbed By The Water: 2,677.8 J
Same Heat In Kilojoules: 2.678 kJ
Heat Per Gram Of Water: 26.778 J/g

Step by step

1Values used
2Heat absorbed by water
3Molar enthalpy
4Molar Enthalpy Change= -535.55 kJ/mol
5Heat Absorbed By The Water= 2,677.8 J
6Same Heat In Kilojoules= 2.678 kJ
7Heat Per Gram Of Water= 26.778 J/g

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is the molar enthalpy negative when the water warms?

Warming water means the reaction gave heat away, and the sign convention makes energy leaving the system negative.

Does the calorimeter itself absorb heat?

Yes, and a careful experiment adds its heat capacity. This simple treatment attributes all the heat to the water, which slightly understates the enthalpy.