Warm-up  What are the Laws of Thermodynamics?  What is heat?

Objectives I  Discuss assumptions of atomic theory.  Discuss temperature and thermal equilibrium.  Calculate thermal expansion.  Discuss anomalous behavior of water.  Apply gas laws.  Apply kinetic theory to define temperature.

Objectives II  Define heat, internal energy, and temperature.  Define and apply specific heat principles to solve calorimetry problems.  Discuss latent heat and apply to solve problems.  Discuss heat transfer processes.

Temperature  Measure of how hot or cold an object is.  Physical properties  Expansion and contraction  Electrical resistance  Color  Thermometers  Temperature scales  Absolute zero

Gas Laws  Boyles Law: V  1/P (absolute pressure)  Charles’s Law: V  T  Gay-Lussac’s Law: P  T

Ideal Gas Law  Ideal Gas Law: PV=nRT where R=universal gas constant (8.315 J/(mol-K))  PV = NkT where k=Boltzmann’s constant = R/N A = 1.38 x J/K and N = number of molecules of gas in the sample.

practice  How many moles of an ideal monatomic gas are in a fixed container of size.5m 3 at 2.0x10 5 N/m 2 and 10°C?

practice  An ideal gas filled sphere of volume.05m 3 inflates to.7m 3 when heated from 20°C to 30°C. If the final pressure is 2.05x10 5 N/m 2, what was the initial pressure?

Temperature of Gasses  Avg translational KE of molecules in a gas is directly proportional to absolute temperature  KE avg = ½ mv 2 = 3/2 k B T  v avg = v rms =

Practice  What is the average translational kinetic energy of molecules in a gas at 37°C?

practice  What is the rms speed of air molecules O 2 and N 2 at room temperature (20°C) if the atomic mass of O is 16 amu, and the atomic mass of N is 14amu?

Thermal Equilibrium  Heat energy flows to establish equilibrium.  Use of thermometers to verify thermal equilibrium of two systems.

Thermal Expansion  Most substances expand with increase in temperature.  Amount varies with material.  L=  L 0  T  V =  V 0  T

Practice  An aluminum block is 51.25m long at 20.0°C. If the coefficient for linear expansion of aluminum is 25.0x10 -6 /C°, what is it’s length at 0°C.

Water  From 0° to 4°C, water contracts to reach densest form. Then, water expands with temperature increases.  Solid water (ice) is less dense than liquid.  Icy ponds

Heat  Transfer of thermal energy due to temperature differences.  James Joule and Mechanical equivalent of heat: J = 1 cal  1 cal is heat required to raise temperature of 1 g of water from 14.5 to 15.5°C.

Specific Heat  c=Q/(m  T) where c=specific heat; Q=heat; m=mass; and T is temperature.  c is property of material.  c v and c p for gases

Practice:  Work on HW 10; you may ask quick questions about HW 9