Gas Laws Flashcards
Gases…
fill containers, mix completely, exert pressure on container
Pressure=
Force/Area
1 Pascal=
1 N/m^2
Manometer
contained gas in one side, liquid mercury, atmospheric pressure on other side; pressure measured by height difference of Hg in mm; Pgas=Patm+Height
Torr vs atm
1 atm =760 mm Hg = 760 torr
Boyle’s Law
P1V1=P2V2; pressure and volume are inverse
Charles’ Law
V1/T1=V2/T2; volume and temperature are direct
Partial Pressure
Total pressure of a container; pressure of each gas combined, sum of pressures
Ideal Gas Law
PV=nRT
Avogadro’s Law
V1/n1=V2/n2; volume and moles are direct
Dalton’s Law
solve for P using ideal gas law/boyles law/avogadros law and use the total vs their sums to find values
Partial Pressure of a gas =
it’s mole fraction (moles of gas/total moles) times it’s total pressure
collecting gas over water
Ptotal= Pgas +Pwater
Mass and Kinetic Energy of a molecule
Kinetic-Molecular theory tells us that lightweight molecules are faster than heavier ones if temperature is constant
molecular speed=
sqrt(3RT/molar mass)
effusion
if gas is given a tiny hole, the lighter the molecules, the faster it leaks
diffusion
the spread of a gas introduced to another, the lighter molecules move and spread faster BUT molecular collisions complicate the rate
Graham’s Law of effusion
r1/r2=sqrt(molar mass2/molar mass1); can compare rate of effusion
Kinetic-Molecular Theory
- If there are a lot of molecules, they move constantly
- Combined mass of molecules is negligible compared to volume
- Molecules aren’t attractive/repulsive
- Collisions are perfectly elastic so avg KE doesn’t change
- KE is proportional to temperature
collecting gases over water
Ptotal=Pgas +Pwater
