States of Matter

Distinctions between gases and solids and liquids

Kinetic Molecular Theory

• 1. Volumeless points in random motion
• 2. Elastic collisions
• 3. No intermolecular interactions (ideal Gas)

Derivation of Gas laws

• Boyles Law
• Charles Law
• Gay Lussac's Law
• Combined gas law
• Avogadro's principle
• Daltons Law of partial pressures

  Graham's Law of Effusion

  

  and since the distance a gas travels is proportional to its velocity (v)

  

Define STP

• standard temperature and pressure
• T = 273.15 K
• P = 1 atm, 760 torr, 760 mm of Hg, 101325 Pa

Standard Molar Volume

at STP for all ideal gases 22.4 L / mol

Solving change of conditions problems

• Consideration of wet gas vs. dry gas
• P must be adjusted for pp of water if the gas is collected over water
• P_dry = P_tot - P_vap(T)

Solving for density and FW using gas laws

Non-ideal gases

• Van der Waals constants
  • a and b are coefficients that adjust P_ideal and V_ideal based on
  • P and V in the eqn. are the experimental values or measured values
• Why the KMT assumptions are wrong?
  • V adjustment - real gases occupy a finite volume
  • P adjustment - gases interact with one another, i.e. repulsion and attraction, and the collisions are not elastic (the frequency of this interaction is concentration dependent)

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