Gas Laws

STP is 1 atm and 0CK = 273 + C (Change ALL temperatures to Kelvin!!!!)

1 atm = 760 mmHg or 760 torr1000 mL=1 L

1 atm = 101.3 kPaMolar Volume of a Gas at STP 22.4 L/mol

V1 = initial volume

Boyle’s Law V1P1 = V2P2V2 = final volume

P1 = initial pressure

P2 = final pressure

Charles’s Law V1 = V2T1 = initial temperature (in Kelvin)

T1 T2T2 = final temperature (in Kelvin)

n1= initial moles

Gay-Lussac’s Law P1 = P2n2 = final moles

T1 T2

Moles and Volume LawV1 = V2

n1 n2

Combined Gas Law V1P1 = V2P2

n1T1 n2T2

Ideal Gas LawPV = nRTP = pressure in atm, kPa, or mmHg (Make sure you pick correct R!)

V = volume in liters

n = number of moles

T = temperature in Kelvin

Ideal Gas Constant =R = 0.0821 L • atm = 8.31 L • kPa = 62.4 L • mmHg

mol • K mol • K mol • K

(Pressure)(volume) = (moles)(ideal gas constant)(temperature)

Daltons LawPT = P1 + P2 + P3 + …….PT = total pressure

P# = the partial pressures of the individual gases

Total Pressure of a Gas = (Sum of the partial pressures of the component gases)

Daltons Lawapplied to Gases Collected by Water Displacement

Patm or PT = Pgas + PH2OPatm or PT = barometric pressure or total pressure

Pgas = pressure of the gas collected

PH2O = vapor pressure of water at specific temperature (table below also on page 899 in textbook)

Water Vapor Pressure

Temperature (ºC) / Pressure (mmHg) / Temperature (ºC) / Pressure (mmHg) / Temperature (ºC) / Pressure (mmHg) / Temperature (ºC) / Pressure (mmHg)
0.0 / 4.6 / 21.0 / 18.6 / 27.0 / 26.7 / 50.0 / 92.5
5.0 / 6.5 / 22.0 / 19.8 / 28.0 / 28.3 / 60.0 / 149.4
10.0 / 9.2 / 23.0 / 21.1 / 29.0 / 30.0 / 70.0 / 233.7
15.0 / 12.8 / 24.0 / 22.4 / 30.0 / 31.8 / 80.0 / 355.1
18.0 / 15.5 / 25.0 / 23.8 / 35.0 / 42.2 / 90.0 / 525.8
20.0 / 17.5 / 26.0 / 25.2 / 40.0 / 55.3 / 100.0 / 760.0

Solids, Liquids, Gases Notes

State / Compressibility / Structure / Shape / Volume / InterM Forces
Solid / No / Ordered / Definite / Definite / Yes
Liquid / No / Fluid / Not Definite / Definite / Yes
Gas / Yes / Fluid / Not Definite / Not Definite / No

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Intramolecular Forces

  • Bonds holding one atom to another atom (3 types listed from weakest to strongest: covalent, ionic, and metallic bonds)

Intermoleulcar Forces (IM)

  • Forces of attraction between one particle and another particle (3 types listed from weakest to strongest: Dispersion, Dipole-Dipole, Hydrogen Bonding)

Postulates of Kinetic Molecular Theory of Gases

Particles of matter (any type) are in constant motion! Because we know this there are a few assumptions we make about gases (called the Kinetic Molecular Theory of Gases):

1. Gas particles move in constant, straight-line motion, until they collide.

2. Gases consist of a large number of tiny particles; these particles are very far apart, therefore gas is mostly empty space.

3. Collisions between gas particles and the container wall are elastic. This means there is no loss of energy.

4. There are no forces of attraction or repulsion between gas particles.

5. The average kinetic energy of gas particles depends on the temperature of the gas.KE = ½ mv2

Nature of Gases

  • Diffusion- gas particles move from a higher to lower concentration
  • Compression- pushing/squeezing particles together
  • Fluid – has the ability to flow (liquids are also fluids)

Description of Gases

  • Volume (measured in L or mL)
  • 1000mL = 1L
  • Pressure (measured in mmHg, torr, atm, or kPa)
  • 1atm=760mmHg or 760 torr
  • 1atm=101.3kPa
  • Temperature (measured in K)
  • K = Cº + 273
  • Amount of Gas Present (measured in mol)
  • 1mol=22.4L (this only applies to gases at STP)
  • 1mol=atomic mass in g (molar mass from periodic table)