Gases
____________________

Explains Gas behavior:

4 parts:
o Gas particles do not attract or repel each other (no I.M. forces).
o Gas particles are much smaller than the space between them.
o Gas particles are in constant, random motion.
o Collisions between gas particles are elastic.
_____________________

Measures the Average Kinetic Energy of a gas.

Temperature and Average Kinetic Energy are ______________ proportional.

At the same temp. all gases have the same average kinetic energy.
Pressure

Created by the collision of particles with other and objects.

Elevation and Atmospheric pressure are inversely proportional.

Higher elevation=less air=less collision=less pressure
How do we measure gas pressure? What is SI unit?
Equivalent Units of Pressure

1 atm (atmosphere)

760 millimeters Mercury (mm Hg)

760 Torr

101.3 kPa (kilopascals)

14.7 psi (pounds/square inch)
STP = __________________________________________
Temperature Conversion

All gas temperatures are calculated using Kelvin.

°C + 2 7 3 = K
Absolute Zero

Temperature at which all molecular motion ____________.

Occurs at 0 K or –273 C
Pressure Conversions
To convert from one pressure unit to another:

Set up a “box”.

Choose conversion factor from equivalent list.

Solve.
Gas Laws

The relationship between the volume, pressure, and temperature of a gas can be
mathematically determined.

Combined Gas Law: V1P1 = V2P2
T1
T2

Boyle’s Law: the volume of a gas is ______________ related to the pressure, at a
constant temperature. V1P1 = V2P2

Charles’ Law: the volume of a gas is ______________ proportional to the
temperature, at a constant pressure. V1 = V2
T1 T2

Gay-Lussac’s Law: the pressure of a gas is _______________ proportional to the
temperature (K) if the volume remains constant. P1 = P2
T1 T2

Dalton’s Law of Partial Pressure:
The total pressure of a mixture of gases is ____________ to the sum of the partial
pressures of each component gas. P = P + P + P …

t
1
2
3
Graham’s law of effusion:
o Effusion:____________________________________________________
____________________________________________________________
The rates of effusion of gases at the same temperature and pressure are
____________________ to the square roots of their molar masses.
√M
rate
A
rate
B
B
=
√M
A
o The _________ smaller the mass of a gas, the _________ the rate of
escape.
o The _____________ the mass of a gas, the ____________ the rate of
escape.

Avogadro’s Principle:
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________

Molar Volume – the volume of 1 mole of any gas at _______.

1 mole of gas = 22.4 L (new)
= 6.022 x 10^23 particles
= Molar Mass (in grams)
Ideal Gas Law

Ideal gases follow all gas laws under all conditions of temrperature and pressure.

________ gases deviate most from ideal gas behavior at extremely high pressure
and low temperature.

This explains why real gases can be liquefied.

Allows you to calculate the amount of a gas (particle density).

PV=nRT
o P=pressure
o V=volume in liters
o n=number of moles
o R=ideal gas constant
o T=temperature (Kelvin)
R (Ideal Gas Constant)
o 1 mol of gas at STP and molar volume
o R=
o R=
o R=
Variations
o n = m/M so…. PVM=mRT
o Where M = molar mass and m = given mass
o d=m/V so….. PM=dRT
o where d = density (in g/L)