Chem 231- Chapter 10 (Gas Laws and Kinetic Molecular Theory)

Properties of the gas state (3)

Uniformly fills any container (“no volume”)

Mixes completely with an other gas (homogeneous)

Exterts pressure on its surroundings (elastic collisions)

Pressure; equation, measurement techniques

Force/Unit Area

Use barometer or manometer

Pressure; units, conversions

Pascal (pa), Standard atmosphere (atm), Millimeter Mercury (mm Hg), Torr

1 atm = 101, 325 Pa

1 atm = 760 mm Hg = 760 torr

Pressure from Manometer

Difference in height of the fluid in the tube will be difference in pressure between the trapped gas and the atmosphere

Gas Laws (7)

Boyle’s Law

Charles’s Law

Combined Gas Law

Avogadro’s Law

Ideal Gas law

Dalton’s Law of Partial Pressures

Graham’s Law of Effusion

Boyle’s Law

P₁V₁=P₂V₂

Conditions of ideal gas, constant T, and constant M

Ideal Gas (3)

Elastic collisions

No particle attractions

No individual particle attractions

Charles’s Law

V₁/T₁=V₂T₂

Conditions: constant P, constant M, ideal gas, and T in Kelvin

Absolute Zero

Reached at 0 K, where molecules stop moving (no volume or collisions)

(extrapolated value)

Combined Gas Law

P₁V₁/T₁=P₂V₂/T₂

Conditions: M is constant, T is in Kelvin, Ideal gas

Avagadro’s Law

V=an

a= proportionality constant

V= volume of gas

n= number of moles of gas

Ideal Gas Law

PV = nRT

R = proportionality constant of 0.09206 LL atm K mol

P= pressure (atm)

V= volume (L)

n= moles

T= temperature (K)

STP

“Standard temperature and pressure”

P = 1 atmosphere

T = O °C

Volume = 22.42 L

Density = Molar mass/22.4 L

Dalton’s Law of Partial Pressures

P_total = P₁ + P₂ + P₃ + …

Mole fraction; definition, equation

Ratio of the moles of a single component to the total number of moles in the mixture

X_a = n_a / n_total

Mole fraction and Partial pressure; equation

P_A = X_A X P_total

Kinetic Theory of Gases (4)

Volume of ind. particles is zero

Collisions of particles with container walls cause pressure exerted by gas

Particles exert no forces on each other

Particles do not all have the same velocity, so an average is used in calculations

Root Mean Square Velocity

V_{root mean square} = √(3RT/M)

R= 8.315 J/K X mol

Effusion; definition

Passage of gas through a small hole into an evacuated chamber

Graham’s Law of Effusion

√M₁/M₂ = rate of effusion₂/rate of effusion₁

Diffusion; definition, equation

The mixing of gases

√M₁/M₂ = distance traveled₂/distance traveled₁

Real Gases (3)

Gas particles have volume

Gas particles show intermolecular attractions

Gas particles experience inelastic collision

Real gases are most evident when…

At high pressure (small volume)

At low temperature (attractive forces become important)

Van der Waal’s Equation

P + a(n/V)² (V-nb) = nRT