Thermal Properties of Matter
1. Temperature and Heat
- Temperature: Measure of the average kinetic energy of particles.
- Heat: Energy transferred due to temperature difference.
- SI Unit of heat: Joule (J)
2. Thermometers and Temperature Scales
- Common scales: Celsius (°C), Fahrenheit (°F), Kelvin (K)
- Conversion:
°C = (5/9)(°F - 32),
K = °C + 273.15
3. Thermal Expansion
- Increase in size of an object due to heat.
- Types: Linear, Area, and Volume expansion.
- Linear expansion: ΔL = αLΔT
- α is the coefficient of linear expansion.
4. Specific Heat Capacity
- Amount of heat required to raise the temperature of 1 kg of a substance by 1°C (or 1 K).
- Formula: Q = mcΔT
- c = specific heat capacity (J/kg·K)
5. Calorimetry
- Science of measuring heat changes.
- Principle: Heat lost by hot body = Heat gained by cold body (no loss to surroundings).
6. Change of State
- Substances change state (solid ↔ liquid ↔ gas) at constant temperature.
- Latent heat is the heat absorbed or released during change of state without temperature change.
- Latent Heat of Fusion: solid ↔ liquid
- Latent Heat of Vaporization: liquid ↔ gas
7. Heat Transfer
- Conduction: Heat transfer through solids without actual movement of particles.
- Convection: Heat transfer through fluids via actual movement.
- Radiation: Heat transfer through electromagnetic waves (doesn’t need a medium).
8. Thermal Conductivity
- Ability of a material to conduct heat.
- Fourier’s Law: Q = kA(ΔT/Δx)
- k = thermal conductivity (W/m·K)
9. Newton’s Law of Cooling
- The rate of cooling is proportional to the temperature difference between the object and surroundings.
- Formula:
Rate ∝ (T - Tenv)