Unit 9

Kinetic Molecular Theory

  • 1. motion of particles are totally random

  • particles move in straight lines (little bend due to gravity) until a collision occurs

  • 2. collisions are perfectly elastic

  • no energy lost through friction

  • 3. volume of particles are negligible compared to distance between particles

  • particles are small

  • most of gas is empty space

  • 4. no attractive force between particles (so quick they don’t have time to react)

  • 5. kinetic energy of the particle is directly kevlin related to absolute temperature (K)

  • gases will act most ideally under high temperature and low pressure

Basic (Physical) Gas Laws

  • P = pressure

  • force/area = newtons/m² = pascal (pa)

  • 101.3 kpa = 1.00 atm = 760.0 mmHg/torr/barr = 14.7 psi (pound over square inch)

  • V = volume = mL or L

  • n = atoms, molecules, moles

  • T = temperature in K

  • K = C + 273

  • Boyles Law = P,V (n,t constant)

  • inverse: P1V1 = P2V2

  • Gay- Lussac Law = P,T (n,v constant)

  • P1/T1 = P2/T2

  • Charles Law = V,T (n,p constant

  • V1/T1 = V2/T2

  • combined gas law: P1V1/T1 = P2V2/T2

Standard Temperature and Pressure

  • T = 0.00 C or 273 K

  • P = 1.00 atm

  • molar volume = 1.00 mol of any gas at STP = 22.4 L

  • Avogadro Law = pressure + number of particles are directly related

  • p/n = K

  • PV/nt = R ( ideal gas constant)

  • n = moles

  • PV = nRt

  • R = 0.0821 atm x L/mol x k

  • n = mass/molar mass

  • MM = mass x r x t/PV

  • Daltons Law of Partial Pressures = Pa + Pb = Ptotal