KINETIC THEORY

							   KINETIC THEORY

The word kinetic indicates motion.
The Kinetic Theory describes the
     motion of gas particles.
          KINETIC THEORY
The Kinetic Theory has
  a few assumptions:

One assumption is that
 the gas particles are
 very tiny and spread
 out. Therefore, a gas
 is mostly EMPTY
 SPACE.
KINETIC THEORY
       Another assumption:
       Gas particles are
         always in motion.
       They bump into each
         other and into the
         walls of the container.
       They undergo ELASTIC
         collisions!
          KINETIC THEORY
• Elastic Collisions are
  collisions that do NOT
  lose or transfer
  energy when they
  collide.
                           Gas particles have
                           little or no attraction
                           for each other. They
                           don’t repel each other
                           either.
         KINETIC THEORY
• Not all gas particles have the same
  amount of kinetic energy. Some are fast
  and some are slow.

• The kinetic energy is proportional to the
  temperature of the gas particles. When
  the temperature is high, the particles have
  more energy and move faster.
     BOYLE’S LAW


In a sealed container, the volume
  and the pressure of a gas are
inversely proportional at constant
          temperature.
            BOYLE’S LAW
• Inversely proportional means that as the
  volume goes up, the pressure goes down.
  OR if the volume goes down, the pressure
  goes up.

Mathematically it looks like this:

                 V1P1 = V2P2
             BOYLE’S LAW
• Consider some gas
  particles trapped
  inside a jar. If the
  volume of the jar is
  500ml at a pressure
  of 740mm Hg, what
  will the volume be if
  the pressure changes
  to 1500mm Hg?
• V1P1 = V2P2
        BOYLE’S LAW
(500ml)*(740mm Hg) = (V2)*(1500mm Hg)

            V2 = 246.7ml
           BOYLE’S LAW
• Try a second problem:

A balloon has a volume of 0.8 liters at a
  pressure of 1.2 atm. What would be the
  new pressure if the volume is increased to
  2.3 liters?

Remember: V1P1 = V2P2
Answer: 0.417 atm
• Now let’s look at      Pressure    Volume
  some data of           133 kPa    0.63 liters
  pressure and volume
  of a gas in a sealed   122 kPa    0.69 liters
  container.             111 kPa    0.75 liters
• What happens to the    100 kPa    0.84 liters
  volume of a gas when
                         88 kPa     0.95 liters
  the pressure
  decreases?             77 kPa     1.09 liters
                         66 kPa     1.27 liters
That’s right, the volume increases!

                            Boyle's Law

                  1.4
                  1.2
                                                      Take a look at the
Volume (liters)




                    1                                 graph of the data, it
                  0.8                                 forms a beautiful
                  0.6
                  0.4                                 hyperbola.
                  0.2
                    0
                        0    50           100   150
                              Pressure (kPa)
     Let’s Review Boyle’s Law
• Use the equation V1P1 = V2P2 to solve
  problems when the pressure and volume
  change while the temperature is constant.

• A pressure vs. volume graph is in the
  shape of a hyperbola.

• Don’t mix units, be consistent!
         Standard Pressure
Standard pressure is a perfect day on the
  beach, right at sea level. The values are:

101.3 kPa = 1.0 atm = 760 mmHg

Get your calculator, it’s time to go to Moodle
 and do some Boyle’s Law Problems.