Ch 9 Gases

simplest model to describe the behavior of gas

Kinetic Molecular Theory

when collisions happen

motion of particles only changes when?

particles of gas are negligibly small, T and avg KE are proportional, collisions are elastic

postulates of KMT

C+ 273.15

C to K

force per unit area

pressure

F/A

P=

760

1 atm is _ torr

V=1/P

Boyle’s Law

inversely proportional

volume and pressure are

V2P2

V1P1=

V and T are proportional

Charles’ Law

V2/T2

V1/T1=

0 volume

absolute zero has what volume

V and n are proportional

Avogadro’s Law

increases

as n increases V does what

increases

as V increases, n does what

P1V1 / T1= P2V2 / T2

combined gas law

PV=nRT

ideal gas law

pressure

P

volume

V

moles

n

universal gas constant

R

temperature in Kelvin

T

273\.15 K and 1 atm

pressure and temperature at STP

22\.4 L/mol

molar volume of a gas at STP

pressure exerted by an individual gas in a mixture

partial pressure

Ptotal=sum of all P for each gas

Dalton’s Law

Pa= (Xa)(Ptotal)

partial pressure equation

gas particles spread out due to a difference in concentration

diffusion

average distance a particles travels between collisions

mean free path

gas escapes through a hole into vacuum

effusion

non ideal

at high P and/or low T, gases become

particle volume becomes significant

as gas is compressed,

a weak interaction can become significant

at low T, collision occur with lower kinetic energy and

over-predicts P

at low T, ideal gas law

underpredicts P

at high P and/or low T, ideal gas law

\[P+ a(n/v)^2\](v-nb)=nRT

Van der Waals equation

correction for particle volume

what do a and b represent in the Van der Waals equation