CHEM 433 - 9/16/11

II. Gases

—> Intro and definitions. (1.1)

A. Ideal Gases

—> The ideal gas Law (1.2)

—> “Equations of “State”

—> Using the Ideal Gas Law

—> Dalton’s Law: Mixtures

READ: Chapter #1

HW: HW #2 via email

Gas: A form of matter that fills any container.

Features : - Molecules in “ceaseless random motion”.- Speeds increase with temperature.- Molecules widely separated except during collision.- Paths “largely unaffected” by IMF. (IDEAL = NO IMF)

Physical State: The “condition” of the system as specified by its physical properties. The State of a pure gas is specified by p, V, T, and n.

Equation of State: An Equation that relates p,V,T (e.g. p = f(n,V,T)).

Perfect (or Ideal) Gas: Obeys: pV=nRT or (p=nRT/V)

Pressure: Force/Area. SI Unit: Pascal (Pa) = N/m2.

http://en.wikipedia.org/wiki/Pressure_measurement

Others: Atmospheres (atm), bar, & Torr (=mmHg). (1 atm = 760 Torr = 1.01325 bar = 1.01325 x 105 Pa).

Standard Pressure: 1 bar (p°)

Mechanical Equilibrium: Equal pressures (e.g. 2 gases separated by a movable piston).

Temperature: A property that indicates the direction of heat flow.

Thermal Equilibrium: Temperatures are equal (no heat flow).

Thermodynamic Temperature Scale: T(K) = Q(°C) + 273.15

0th Law of Thermodynamics:

If A ~ B, and B ~ C —> A ~ C (~ = in Thermal EQ w/)

Diathermic Boundary: Change of state can occur upon contact (heat transfer allowed).

Adiabatic Boundary: No change of State occurs upon contact (no heat transfer).

The unofficial mascot of CHEM 433:

The frictionless movable pistonF.M.P.

Boyle’s Law: PV = const.or: p = 1 / V(constant T,n)

Charles’ Law(s) : P ~ T V ~ T

(constant n, and p or V)

Avagadro’s Principle:

V ~ n

(constant T, p)

What is the volume of 1 mol of gas at:

a) STP (T=0°C and p = 1 atm) ?

b) SATP (T=298.15K, p=1 bar)?

a) 22.4 L

b) 24.8 L

Using the Combined Gas Law:

Calculate the final temperature when 1 mol of gas a SATP is compressed from 24.8 To 12.4 L and the pressure increases from 1.0 to 2.0 bar?

THE SAME - about 298K

P1V1T1

P2V2T2

Using Dalton’s Law:

Calculate PN2, PO2 and PAr in the atmosphere, assume PTOT = 1.00 atm.

moles

PN2 = 0.78 atm, PO2 = 0.21 atm, PAr = 0.0093 atm