1. Physics II Thermology; Electromagnetism; Quantum physics.

2. Chapter 15 Temperature and the Ideal Gas Law

3. Basic concepts 3 Thermal system & environment State & state variables Volume, mass, pressure, temperature… Macroscopic: thermodynamics Atoms or molecules, and their motion Microscopic: kinetic theory (statistic physics)

4. Atomic theory of matter 4 Atom; atomic mass 1u=1.66×10 -27 kg Brownian movement Three phases of matter: solid, liquid, gas Difference: distance and forces between atoms

5. Thermal equilibrium & temperature 5 0 th law of thermodynamics: If two systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. 2 contacting objects heat transfer Thermal equilibrium same temperatureThermal equilibrium 0th law: definition of temperature

6. Equilibrium state 6 For a gas system, it means constant P, V, T Variables are the same throughout the system and not changing in time → equilibrium state equilibrium stateIsolated system long time Closed system & open system Basic system in this chapter: a given quantity of gas at equilibrium state

7. The gas laws 7 Boyle’s law: (constant T ) Charles’s law: (constant P ) Gases: not too dense, not too low T

8. Absolute temperature 8 Changing scales: 0 K or -273.15 ℃ : absolute zero of temperature Gay-Lussac’s law: (constant V ) Celsius scale & Absolute or Kelvin scale Experimental relationship, not real laws Useful technique: only one changing variable

9. The Ideal gas law 9 Consider the amount of gas: Ideal gas law / equation of state for an ideal gas: Universal gas constant For fixed quantity of gas: n: number of moles 1) Approximation2) Equilibrium state

10. Avogadro’s hypothesis 10 Equal volumes of gas at the same pressure and temperature contain equal numbers of molecules. R ( universal gas constant ) is the same for all gases. k: Boltzmann’s constant Avogadro’s number:

11. Volume at STP 11 Example1: (a) Determine the volume of 1 mol ideal gas at standard conditions (STP); (b) Estimate the mass of air in a 2.0L breath. Solution: (a) Ideal gas law: PV = n R T (b) Temperature of human

12. Bubble in a lake 12 Example2: An air bubble (1.0cm 3 ) is at the bottom of a lake (37m deep, 5 ℃ ). What is its volume just before it reaches the surface (21 ℃ )? Solution: Ideal gas law: PV = n R T The amount of gas doesn’t change

13. Two bottles 13 Question: There are two same test tubes A and B. Tube A is heated at one end, and the temperature in A is changing from 900K to 300K uniformly. Gas in tube B has a constant temperature 600K. Compare the number of moles of gas in A and B. A B ?