1. The Kinetic Model
Brownian Motion
- Experiment: Smoke particles in air observed under microscope
- Observation: Random motion of particles
- Einstein's Explanation: Result of molecular collisions
States of Matter
Solid
- Fixed, regular arrangement
- Vibrational motion only
- Strong intermolecular forces
- High density
Liquid
- Random, close arrangement
- Free to move past each other
- Moderate forces
- Moderate density
Gas
- Random, far apart
- Rapid, random motion
- Negligible forces
- Low density
2. Temperature
Key Concepts
- Thermal Energy vs Temperature: Total KE vs average KE
- Absolute Zero: 0 K (-273.15°C), minimum possible temperature
- Triple Point: Unique T&P where all 3 phases coexist
- Kelvin Conversion: K = °C + 273.15
- Thermal Equilibrium: No net heat flow between objects at same temperature
T(K) = T(°C) + 273.15
3. Phase Changes
Definitions
- Internal Energy: Sum of KE and PE of all molecules
- Latent Heat of Fusion: Energy for solid-liquid change
- Latent Heat of Vaporization: Energy for liquid-gas change
Temperature vs Time Graph
[Diagram: Heating curve showing plateaus at phase changes]
• During phase changes: Internal energy increases but temperature remains constant
• Latent heat = energy to overcome intermolecular forces
• Absolute zero unattainable due to quantum fluctuations
Q = mcΔT (Specific Heat Capacity)
Q = energy (J), m = mass (kg), c = SHC (J/kg·K), ΔT = temp change (K)
4. PAG 11.2: Specific Heat Capacity
Electrical Method
- Set up circuit with power supply, ammeter, voltmeter, and heater in material
- Measure mass and initial temperature
- Apply known electrical power for measured time
- Record temperature change
- Calculate using: c = IVt/mΔT
Hazards & Controls
- Electric shock: Use low voltage, insulated wires
- Burns: Allow cooling time, use tongs
- Spills: Secure containers, absorbent materials ready
Circuit Diagram
[Diagram: Power supply, ammeter in series, voltmeter parallel to heater, heater in material]