Gas Laws Cheat Sheet - Georgetown ISD



Gas Laws Cheat Sheet

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

1 atm = 760 mmHg or 760 torr 1000 mL=1 L

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

V1 = initial volume

Boyle’s Law V1P1 = V2P2 V2 = final volume

P1 = initial pressure

P2 = final pressure

Charles’s Law V1 = V2 T1 = initial temperature (in Kelvin)

T1 T2 T2 = final temperature (in Kelvin)

n1= initial moles

Gay-Lussac’s Law P1 = P2 n2 = final moles

T1 T2

Moles and Volume Law V1 = V2

n1 n2

Combined Gas Law V1P1 = V2P2

n1T1 n2T2

Ideal Gas Law PV = nRT P = 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 Law PT = 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 Law applied to Gases Collected by Water Displacement

Patm or PT = Pgas + PH2O Patm 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 |

Graham’s Law

Rate of diffusion/effusion of A = √(MB / MA) M = molar mass of that compound

Rate of diffusion/effusion of B Gas A is the lighter, faster gas

Rate of diffusion/effusion is the same as the velocity (or speed) of the gas.

After the rates of diffusion/effusion for two gases are determined, the gas with the lower molar mass will be the one diffusing/effusing faster.

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