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Thermodynamics · Quick Reference
Calorimetry Cheat Sheet
In one line: calorimetry is the science of measuring heat transfer — by tracking how much heat flows into or out of substances, we can find specific heat capacities, verify energy conservation, and study reactions.
Key Ideas
1The Principle of Calorimetry. In an isolated system, heat lost by a hotter object equals heat gained by a cooler object -- energy is conserved during the exchange.
2Calorimeter. A device designed to measure heat flow during a physical or chemical process, insulated to prevent heat loss to the surroundings.
3Setting Up a Calorimetry Equation. Heat lost by the hot substance = heat gained by the cold substance: m1*c1*(T1-Tf) = m2*c2*(Tf-T2), where Tf is the final equilibrium temperature.
4Finding an Unknown Specific Heat. By measuring the final equilibrium temperature after mixing a known and unknown substance, you can solve the calorimetry equation for the unknown specific heat.
5Heat of Fusion and Vaporization. The heat required to change a substance's phase (like ice to water, or water to steam) without changing its temperature -- this energy goes into breaking molecular bonds, not raising temperature.
Worked Examples
100g of water (c=4.2 J/(g*°C)) at 80°C is mixed with 100g of water at 20°C. Find the final equilibrium temperature.
50°C
200g of metal at 100°C is dropped into 300g of water (c=4.2) at 20°C, reaching equilibrium at 25°C. Find the metal's specific heat.
c1 = 0.42 J/(g*°C)
Why does the temperature of ice water stay at 0°C while ice is melting, even as heat is continuously added?
The heat goes into the phase change (melting) rather than raising temperature, until all the ice has melted
Formulas
Heat lost = Heat gained: m1*c1*(T1-Tf) = m2*c2*(Tf-T2)
Practice Yourself
50g water at 90°C mixes with 50g water at 10°C. Find the equilibrium temperature.
50°C (simple average since masses/c equal)
What does a calorimeter measure?
Heat flow during a physical or chemical process
What is the core principle of calorimetry?
Heat lost by a hotter substance equals heat gained by a cooler substance (in an isolated system)