Chapter 11 gases and kinetic molecular theory Flashcards
properties
- assumes both the shape and volume of its container
- compressible
- low densities
- miscible in all proportions
Kinetic molecular theory
the theory that models the behavior and properties of gases
- the size of gas particles is negligibly small compare to the volume they occupy
- gas particles are moving at random with no attractive forces between them
- collisions between particles are completely elastic
- the average kinetic energy of particles is proportional to the kelvin temperature
average kinetic energy
KE=1/2mv^2
at a given temperature lower mass molecules move faster
mean free path
though molecules are moving fast. the average distance that a molecule travels between collisions
diffusion
the process by which molecules spreed out
molecules move from region of high concentration to a region of low concentration
effusion
the process by which a gas escapes from a container through a tiny hole
grahams law
rateα√1/M
rate gas A÷rate gas B= √Mb/Ma
Pressure
a force exerted per unit area
SI unit: Pascal, Pa
1Pa= 1n÷m^2
atmospheric pressure
1 atm=101,325 Pa
=101.325 kPa
=14,7 lbs/in^2
760 mmHg=760torr
Barometer
instrument used to measure the atmospheric pressure
P=hgd
h: height
g: gravitation acceleration, 9.834 m/s
d: density, kg/m^3
manometer
instrument used to measure the pressure of a gas sample
Boyle’s law
the volume of a fixed amount of gas at constant temperature in inversely proportional to its pressure
Vα1/p constant T and n
V-P= constant V1P1=V2P2
charles law
the volume of a fixed amount of gas at constant pressure is directly proportional to its kelvin temperature
VαT constant P and n
V/T=constant
V1/T1=V2/T2
avogadros law
the volume of a gas at fixed pressure and temperature is directly proportional to the number of moles of the gas
present
Vαn constant V and T
V/n=constant
V1/N1=V2/N2
amontons law
the pressure of a fixed amount of gas at a fixed volume is directly proportional to its kelvin temperature
PαT=constant V and n
P/T=constant
P1/T1=P2/T2
Standard temperature and pressure, STP
to compare gases we can fix parameters of T and P
STP=0ºC and 1 atm
PV=nRT
density of gases
at STP the volume of 1 mole go gas is 22.41L
D=mass/volume
general equation for densities of gases
d=PM/RT
moles can be converted into grams using molar mass
deviations
any gas that obeys the ideal gas law equation is said to be an ideal gas
deception over under two condition:
- High pressure
- Low temperature
high pressure KMT
the size of gas particles is negligible compared to the volume they occupy.
increase number of particles
reduce the volume
real gas:the volume of the particles are no longer negligible
idea gas: V=nRT/P VDW V=nRT/P +rb V=nb=nRT/P
the volume of the ideal gas is important. b: correction factor, L/mol
low temperature KMT
gas particles are moving at random with no attractive forces between them
real gas: as molecules slow down attractive forces causes them to stick together
this causes a drop in collision which decreases the pressure
ideal gas P=nRT/V VDW P=nRt/V-a(h/v)^2 P+a(n/v)^2=nRT/P
the pressure decreases due to slower molecules
a: correction factor, L^2•atm/mol^2
van der Waals equation
VDW[p+a(n/v)^2][v-nb]=nRT/P
particle pressure, PgasA
the pressure due to any individual gas component in a gas
most gas samples are mixtures
Ptotal= ntotalRT/v = Pa+Pb+Pc
dalton law
in a mixture of non-reacting gases the total pressure exerted is equal to the sum of the partial pressures of the individual gases
Pa=XaPtotal
X:mol fraction=mol component A/total moles
