Gas Laws

Chapter 14

Kinetic Molecular Theory of Gases

No attraction/repulsionVolume of particles is 0Constant motionElastic collisionsTemperature equals the average kinetic

energy of all particles

Factors Affecting Gas Pressure

Amount of Gas (n=moles)

Volume (Liters)

Temperature (Kelvin)Remember: K=oC +273

1atm = 760 mm Hg = 760 Torr = 101.3 kPa = 14.7 psi

Boyle’s Law

At constant temperature, pressure and volume are indirectly related.

P1V1 = P2V2

Practice: Boyle’s Law

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?

Charles’s Law

At constant pressure, volume and temperature are directly related.

V1/T1 = V2/T2

Practice: Charles’s Law

Calculate the final temperature of a gas in Celsius when 2L of the gas at 128K is compress to 0.5L?

What About Pressure and Temperature? Gay Lussac’s LawAt constant volume,

pressure and temperature are directly related

P1/T1 = P2/T2

Practice

What is the final pressure of a sample of gas that has an initial pressure of 89.3kPa when its temperature is raised from 25oC to 100oC?

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 (Section 14.2):# 7-14

IDEAL GAS LAW

PV=nRT

R= 0.0821 L*atm/mol*K = 8.31 L*kPa/mol*K

Calculate the pressure in a 212 Liter tank containing 23.3 kg of argon gas at25°C?

Ideal v. Real Gases

They’re the same except at EXTREMELY LOW TEXTREMELY HIGH P

Assignment

Section 14.3 Assessment# 25-30

Ideal Gas Law and Molar Mass

M=mRT/PV given n=m/M

Where n=moles, m=mass and M=molar mass

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 given n=m/M and D=m/V

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

Gas Stoichiometry

If 1.39 g of ethane(C2H6) is reacted with oxygen, what volume of carbon dioxide is produced at:  STP?

12.3oC at 107.4KPa?

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

                              

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 Questions5 problems requiring elegant solutions