1 Ch 10.1 Kinetic Theory: 5 assumptions 1.small particles - far apart 2.Movement random, rapid & continuous 3.Collisions are elastic 4.No attractive/repulsive forces 5.Average kinetic energy depends on temp.

2 Ch 10.1 Properties specific to gases: –Expand –Compress –Low density –Fluid –Diffuse: [↑]to [↓] until equal Rate depends on, speed, diameter, attractive force Calculated by v 1 m 2 v 2 m 1 Effuse: force through small opening. –Joule Thomas effect

3 Ch 10.2 –Note: the lower the temp of a gas the more “ideal” it is –Pressure = caused by the collisions of gas particles against it’s container. –Standard Pressure units kPa= 760mmHg or Torr for Torricilli (barometer) 1 ATM –STP = standard temp and pressure

4 Ch 10.2 Standard Temperature –0 o C or 273 K Temp is a measure of kinetic energy Kinetic energy = mv 2 / 2 Absolute zero is where (theoretically) all particle motion ceases.-273 o C or 0 K

5 Ch 10.3 In 1662 Robert Boyle: If amount and temp remain the same then, Boyle’s Law = P 1 V 1 = P 2 V 2 Inverse proportion: As one goes up the other goes down.

6 Ch Jacques Charles showed that the volume of a gas varied directly with Kelvin temp Charles’ Law: V 1 = V 2 T 1 T 2 K= o C *** always calculate in Kelvin for gases***

7 Ch Joseph Gay-Lussac recognized that for each 1 o C increase the volume would increase by 1/273. Therefore at -273 o C a gas would have no volume or disappear BUT ALL gases turn to liquid before this happens. He also noticed : P 1 = P 2 T 1 T 2

8 Ch 10.3 The Combined Gas Law: P 1 V 1 = P 2 V 2 T 1 T 2

9 Ch 10.3 John Dalton found that in the absence of a chem rxn the pressure of a gas mixture is the sum of the individual gas pressures. The partial pressure is the pressure of one gas in a mixture so it’s only part of the total pressure! P total = P gas + P other gases P gas = P total – P other gases

10 CH 10.3 When a gas is collected through water displacement –The left over water vapor pressure exerts a pressure that must be accounted for. Use a water vapor chart (pg 899) P gas = P atm – P H2O at what ever temp

11 CH 10.3 A sample of Oxygen gas is collected in a 175ml container over water at 15 o C and the barometer read 760 torr. What volume will the dry gas occupy at 770torr and 15 o C. Adjusting for the water vapor 760 torr torr = torr should be used instead of 760 torr.

12 IDEAL GAS Law Ideal Gas equation is derived at by combining all 4 variables concerned with the physical characteristics of gases (volume, temperature, pressure & # of particles)

13 IDEAL GAS Law Ideal Gas Equation: PV=nRT R is a constant used in calculations involving the ideal gas equation R=.0820 LAtm molK R = (1atm)(22.4L)/ (1mol)(273K) n = number of moles

14 Molecular Mass and Density The calculation of the molecular mass (M) and Density (D) can be determined using the ideal gas equation. M = mRTD= MP PV RT This is important in determining the formulas and structures of unknown compounds.