THE KINETIC THEORY AND THE STATES OF MATTER

1. What’s happening when the food coloring is dropped into the beaker of water? 2. What is it called? 3. Why does it happen? 4. What do we know about the size of the particles? 5. What do we learn about collisions between particles from the motion demonstrator?

THE KINETIC THEORY 1.All matter is composed of very small particles 2.These particles are in constant motion 3.Collisions between particles are perfectly elastic

FACTS ABOUT MOLECULES IN MOTION 1.At 25 o C the average O 2 molecule travels at1700 Km/hr or 1062 mi/hr. 2. Each O 2 molecule travels 314 times its own diameter before colliding with another O 2 molecule. This average distance traveled between collisions is called the mean free path. 3. There are 4.5 billion collisions per second per molecule.

What’s happening in the test tube with vinegar and baking soda? Pressure is defined as force per unit area.

1. Kilopascals (KPa), 2. millimeters of mercury (mmHg) 3. torr 4. pounds per square inch (lbs/sq in or psi) 5. atmosphere (atm) UNITS OF PRESSURE

Pressure Unit Conversions 1atm = 760 mmHg = 760 torr = 101.3KPa = 14.7psi Do the following conversion problems: atm = how many Kpa? torr = how many atm and mmHg? Kpa = how many mmHg? psi = how many atm and KPa?

Standard Pressure It is measured at sea level and is 101.3KPa or 760 mmHg or 1 atm or 760 torr or 14.7psi. EXAMPLES of pressure at work all around us.

Measuring Pressure A barometer is the instrument we use for measuring atmospheric pressure.

Torricelli ( ) invented the barometer to demonstrate that air exerted pressure. He filled a thin glass tube that was closed at one end with mercury. While covering the open end so that air could not enter he inverted the tube and placed it in a dish of mercury. The height of the mercury fell to about 760 mm. Changes in air pressure caused the mercury column to raise and fall - increase caused it to rise, decrease caused it to fall.

Calculating Pressure of a gas with a Barometer 98mm Find the air pressure in atm and KPa if the barometer reading is 756 mm. Step 1:Convert mm Hg to atm by dividing by 760 since 1 atm = 760 mmHg. 756 divided by 760 =.995 atm. Step 2 : convert atm to KPa by multiplying by since KPa = 1 atm..995 atm X KPa = KPa. 756 mm

Manometer A manometer is an instrument used to measure gas pressure in a closed container. In a manometer, a flask is connected to a U- tube that contains mercury. The gas particles push down on the mercury in the tube. The difference in the height of the mercury in the two arms is used to calculate the pressure of the gas in the container.

Calculating Pressure of a Gas with a Manometer 220mm If the difference in the height of mercury in the two tubes is 220 mm what is the gas pressure in atm? What is it in KPa? Step 1: Convert mm Hg to atm by dividing mm Hg by 760 since 760 mmHg = 1 atm. 220mm divided by 760 =.289 atm. Step 2 Convert atm to Kpa by multiplying by since 1 atm = KPa X.289 = 29.3 KPa.

Temperature 1. Definition - A measure of the average kinetic energy of the molecules of a substance Kinetic Energy is = 1/2 mass x velocity 2 Temperature of a material is related to the velocity of its particles

Heat is energy transferred due to differences in temperature. The energy always flows from higher to lower temperature.

Temperature Scales 1. Celsius or Centigrade - based on the boiling and freezing points of water. Designed so that there would be 100 degrees between them.

2. Kelvin - based on absolute zero, the temperature where all molecular motion stops. 0 K is -273 o C Temperature Conversions K = o C o C = K -273

Standard Temperature Just as there is standard pressure there is also standard temperature. Together standard temperature and pressure are abbreviated STP. They are the standard set of conditions for experimental measurements, to enable comparisons to be made between sets of data usually when working with gases. Standard temperature is 273K or 0 °C.

Do the following Sample Conversions: 1.86 K to o C6. 23 o C to K 2.191K to o C7. 58 o C to K 3.533K to o C o C to K 4.321K to o C9. 18 o C to K 5.894K to o C o C to K

The Four States of Matter This figure shows the four states of matter: ice (solid), liquid (water), gas (water vapor) and plasma (hydrogen nuclei and electrons). In the upper right hand corner is a picture of a galaxy of stars (fusion reactors).

Kinetic Theory and States of Matter 1. GAS -Particles move independent of each other and in a straight line -Particles have random motion

Gas (Continued) -A Gas assumes the shape and volume of its container

2. LIQUID -Particles have a vibratory movement about a moving point. -Particles change positions about each other continually. -Liquids have a definite volume and assume the shape of their container.

3. SOLID -Particles occupy a fixed position in relation to surrounding particles -Particles vibrate about a fixed point. -Particles closely packed together in a particular pattern. -Solids have a definite shape and volume. (See video clip disk 2 chapt.17)

4.Plasma - Most abundant form of matter in the universe. Over 99% of the universe is composed of plasma.

- Created when enough heat is applied to remove the electrons from the grip of the nucleus. Results in free electrons and positive ions -Seen in the fusion process of the Sun. -Examples of plasmas on earth are neon signs, fluorescent lights and laser tubes.

-Van Allen radiation belts surrounding the earth are plasma. Collisions between the charged plasma particles in the magnetosphere and molecules in the earth’s upper atmosphere produces a phenomenon known as the aurorae. Aurora borealis in the north and Aurora australis in the south.

-Since a plasma contains charged particles it is affected by electric and magnetic fields -The study of plasma is called magnetohydrodynamics

What determines the state of a substance at room temperature? The bonding or attractive forces between the particles of the substance. A solid typically has strong attractive forces and a gas weak attractive forces. A liquid has intermediate forces of attraction.