Gas Laws

Avogadro's Law. The Ideal Gas Law. P V = n R T. P1 V1 n1 T1. = P2 V2 n2 T2. If pressure and moles do not change in the problem, omit those variables. ...

168 downloads 645 Views 90KB Size
A. Romero 2010

Gas Laws CHEM 1A Boyle’s Law

Charles’s Law

Gay-Lussac’s Law

The Combined Gas Law

Avogadro’s Law

P1 V1 = P2 V2

V1 V = 2 T1 T2

P1 P = 2 T1 T2

P1 V1 P V = 2 2 T1 T2

V1 V2 = n1 n2

Graham’s Law of Effusion (for relative velocities or rates of diffusion/effusion) Rate* Gas A = Rate* Gas B

Root Mean Squared Velocity 3RT M

urms =

MB MA

R = 8.31451 J/K∙mol M = molar mass in kg/mol

* indicate the specific type of rate (Velocity, Rate diff., or Rate eff.)

Dalton’s Law of Partial Pressures

The Ideal Gas Law

Mole Fraction

PV= nRT

nA PA A = = ntotal Ptotal

a = van der Waals constant b = van der Waals constant A = mole fraction of A d = density M = molar mass n = # of moles P = pressure PA = partial pressure gas A R = 0.08206 L·atm/K·mol T = temperature V = volume STP = 0ºC & 1 atm

Ptotal = PA + PB + PC …

At STP: 1 mole = 22.4 L 1 atm ≡ 760 torr

dRT M = P

K = °C + 273.15 Important Rules for Units  T always in Kelvin  P1 & P2 units match  V1 & V2 units match  All P units in Dalton’s Law match  All units match those of R in the Ideal Gas Law

van der Waals Equation n Pobs + a V

2 V–nb = nRT

Atm · L2 mol2

L mol

Note: Many of the gas laws can be found by solving the Ideal Gas Law for R, and then omitting any variables that do not change. Example:

The Ideal Gas Law

P1 V1 P V = 2 2 n1 T1 n2 T2

PV= nRT R =

PV nT

If pressure and moles do not change in the problem, omit those variables Charles’s Law V1 V2 = T1 T2