Thermochemistry Calculator
Calculate heat absorbed or released using q = mcΔT.
Select a substance from a list of specific heat capacities and enter mass and temperature change.
The fundamental equation of calorimetry relates heat, mass, specific heat capacity, and temperature change:
q = m × c × ΔT
Where q is the heat transferred (joules), m is the mass (grams), c is the specific heat capacity of the substance (J/g·°C), and ΔT = T_final − T_initial.
If ΔT is positive (temperature increased), q is positive — the substance absorbed heat (endothermic process). If ΔT is negative, q is negative — heat was released (exothermic process).
Specific heat capacities (J/g·°C):
- Water (liquid): 4.184: the highest of common substances, which is why water is such an effective heat sink
- Ice: 2.093
- Steam: 2.010
- Ethanol: 2.44
- Aluminum: 0.897
- Iron: 0.449
- Copper: 0.385: low specific heat means copper heats up quickly
- Gold: 0.129: the lowest of common metals
- Concrete: 0.840
Water’s exceptionally high specific heat is why coastal climates are milder than inland ones, why oceans buffer climate change, and why water is used as a coolant in engines and nuclear reactors.
A practical application: how much energy does it take to heat 500g of water from 20°C to 100°C? q = 500 × 4.184 × 80 = 167,360 J = 167.4 kJ. That is about 0.047 kWh — roughly 0.6 cents of electricity at typical US rates.
The sign of q matters: negative q means heat flows out of the system into the surroundings. Exothermic reactions (combustion, neutralization) release heat; endothermic reactions (dissolving ammonium nitrate) absorb it.
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This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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