Kinetic Theory

1) All matter is made up of tiny particles. These particles are close together in solids and liquids but
are quite far apart in gases. For example, the nitrogen and oxygen molecules in our atmosphere are
a distance of about 300 times their radii.

2) The particles in all forms of matter are in constant motion. The extent of this motion depends upon the
temperature. Molecules or atoms move faster in hot matter and slower in colder matter.

3) When the particles collide with each other or the side of the container, there is no loss of kinetic energy.

4) At a given temperature, the kinetic energies of a population of particles varies, but all are pretty close
to the average. The distribution of kinetic energies in a population of molecules resembles a bell curve, with
most molecules having close to the average kinetic energy, but with some with significantly more, or less kinetic
energy.
 

Some have lower than average kinetic energies, some have higher than average kinetic energies, but most have a kinetic energy close to the average.

Layers of the Atmosphere

Troposphere - the layer from ground level to about 10-12 km elevation
                       - there is continuous mixing of gases in the troposphere which keeps the atmosphere fairly uniform
                       - today's air is similar to air from long ago except for today's elevated CO2 levels
                       - contents:    78 % N2, 21 % O2, 0.9 % Ar, 0.1 % trace gases

Stratosphere - 2nd layer of atmosphere above the troposphere
                        - starts at about 12 kn elevation and extends to about 30 km elevation
                        - contains ozone, O3, an essential gas that helps block harmful UV radiation from the sun

Ionosphere - above stratosphere
                    - contains ionized gases
 

Measurements Involving Gases

Measuring mass of gases can be difficult due to buoyancy. When working with gases, there are three measurements
that are usually made.

1) Volume - Liters

2) Temperature - C, K

The absolute temperature scale is based on the Kelvin. Celsius temperature can be converted to Kelvins by using the
following formula:

Kelvins can be converted to Celsius temperature by

3) Pressure - force exerted per area (F / A). Pressure is due to the weight of the atmosphere pushing down upon us. At higher
elevations, there is less gas above us so the pressure is less. This explains why mountain climbers may need oxygen tanks
when they climb the taller mountains like Mt. Everest.

There are several units of pressure. They include psi (lbs / sq in), atmospheres, kiloPascals, inches or millimeters of mercury.

Moles and Gases

We demonstrated in class that there are optimal ratios of gases in reactions. When the ratio of hydrogen to oxygen was 2:1, we got the biggest bang because they react in that ratio.

The equation tells us that 2 hydrogens react with one oxygen to form 2 waters. We know we can substitute moles so that 2 moles of
hydrogen eract with one mole of oxygen etc. Because the optimal volume ratio is 2:1 , there must be twice as many moles of hydrogen in 2 "volumes" of hydrogen as one "volume" of oxygen. This means that:

Equal volumes of gases at the same temperature and pressure have equal numbers of moles of gas. This is Avogadro's Principle.

At standard temperature and pressure (STP), 1 mole of any gas occupies 22.4 liters.

Effect of Temperature and Pressure on Volume

Boyles Law

Boyles Law states that the volume of a gas is inversely related to the pressure acting on a gas. In other words, as the pressure acting
on a gas increases, the volume decreases and vice versa.

The equation we use for Boyles law is                                        P1V1 = P2V2

P1 = initial pressure
V1 = initial volume
P2 = final pressure
V2 = final volume

If we know the initial volume and pressure we can rearrange the above equation to solve for final volume at a different pressure.

                                                                                                        V2 = V1 x P1
                                                                     P2

Charles Law

Charles Law states that the volume of a gas is directly related to the Kelvin temperature. In other word, as temperature of the gas
increases, the volume of the gas increases and vice versa.

The equation we use for Charles law is                                     V1  =  V2
                                                                                                        T1        T2 

T1 = initial temperature
V1 = initial volume
T2 = final temperature
V2 = final volume

If we know the initial volume and temperature, we can rearrange the above equation to solve for the final volume at a different
temperature.

                                                                                                    V2 = V1 x T2
                                                                  T1

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