Calorimetry (Mixing)
T_eq = (m₁T₁ + m₂T₂)/(m₁+m₂) — mix two waters.
Key Notes
Calorimetry: study of heat transfer between bodies. Used to measure specific heat capacities.
Principle: when two bodies at different T are placed in thermal contact, heat lost by hot = heat gained by cold (no losses).
Heat balance: m₁·c₁·(T_hot − T_f) = m₂·c₂·(T_f − T_cold). Solve for T_f or unknown c.
Calorimeter: container designed to minimize heat losses (insulated double-walled, or vacuum-jacketed).
Water is commonly used in calorimeters because of its high and well-known c.
Latent heat: heat required for phase change at constant T (e.g., ice → water).
Method of mixtures: classic experiment using known reference substance and water.
Bomb calorimeter measures heat of combustion at constant volume.
Formulas
Heat lost = heat gained
Energy balance, no losses.
Final temperature
Weighted average by heat capacities.
Heat balance with phase change
Add latent heat term L for melting/vaporization.
Important Points
Heat lost by hot body = heat gained by cold body (in absence of losses).
Final T is the WEIGHTED average — weighted by m·c (heat capacity).
If amounts of heat are equal, larger m·c side changes T less.
Calorimetry experiments require GOOD INSULATION — otherwise heat leaks to environment.
Phase changes happen at FIXED T — heat goes into the phase transition, not raising T.
Specific heat of an unknown substance can be measured by heat balance with water of known mass and c.
Calorimetry (Mixing) notes from sciphylab (also known as SciPhy, SciPhy Lab, SciPhy Labs, Physics Lab). Class 11 physics revision for JEE Mains, JEE Advanced, NEET UG, AP Physics 1/2/C, SAT, and CUET-UG.