Gas Laws Chapter 14

Kinetic Molecular Theory of Gases No attraction/repulsion Volume of particles is 0 Constant motion Elastic collisions Equal kinetic energy

Boyle’s Law At constant temperature, pressure and volume are indirectly related. P1V1 = P2V2 A gas system has an initial volume of 2.36L with the pressure unknown. When the volume changes to 2290mL the pressure is found to be 6390torr What was the initial pressure in atm?

Practice

Charles’s Law At constant pressure, volume and temperature are directly related. V1/T1 = V2/T2

What About Pressure and Temperature? At constant volume, pressure and temperature are directly related P1/T1 = P2/T2

Combined Gas Law P1V1/n1T1 = P2V2/n2T2 http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/gasesv6.swf A closed gas system initially has pressure and temperature of 1.56atm and 629K with the volume unknown. If the same closed system has values of 195torr, 9940mL and 523K, what was the initial volume in L?

ASSIGNMENT Practice Problems: # 17-14

IDEAL GAS LAW PV=nRT R= 0.0821 L*atm/mol*K Calculate the pressure in a 212 Liter tank containing 23.3 kg of argon gas at 25°C?

Ideal v. Real Gases They’re the same except at EXTREMELY LOW T EXTREMELY HIGH P

Assignment Section Assessment # 25-30

Ideal Gas Law and Molar Mass M=mRT/PV How many grams of gas are present in a sample that has a molar mass of 70 g/mol and occupies a 2.00 L container at 117kPa and 35.1 oC?

Ideal Gas Law and Density D=MP/RT What is the density of a gas at STP that has a molar mass of 44.0 g/mol?

Dalton’s Law of Partial Pressure Pressure and moles of gas are directly proportional. Ptotal= P1 + P2 + P3 + … http://www.tlv.com/global/US/steam-theory/steam-partial-pressure-pt1.html

Remember? Gas Stoichiometry

Avogadro’s Principle Equal volumes of gas at the same temperature and pressure have equal numbers of particles. Translation: 1 mole = 22.4 L = 6.02 x 1023 gas particles What is a mole? In Chemistry a mole is NOT an animal!!                               

Diffusion/Effusion Diffusion- gases move toward areas of lower concentration Effusion- gas escaping through tiny holes in container

Graham’s Law of Gaseous Effusion

TEST 30 MC Questions 5 problems requiring elegant solutions