Kinetic Theory

1. Kinetic Theory Ch 16 Sect 1

2. Kinetic Theory • Explanation of how particles in matter behave • There are 3 assumptions associated with the kinetic theory • All matter is composed of smaller particles (atoms) • These particles are in constant random motion • These particles collide with each other and their boundaries

3. Kinetic Theory and Energy • The movement of the particles (atoms) with in an object depend on energy • Energy is measured as heat • As energy increases (gets hotter) particle motion increases • As energy decreases (gets colder) particle motion decreases

4. Measuring Particle Energy • There are 2 different measurements used when measuring the energy within an object • Thermal energy-When using thermal energy you measure the total amount of energy for all of the particles in the object (substance) • More thermal energy = More (faster) motion • Less thermal energy = less (slower) motion

5. Measuring Particle Energy (cont) • Average Kinetic Energy (AKE)-The average kinetic energy shows the average energy for all the particles in an object (substance) • Most commonly know as the temperature of an object (substance) • As temperature goes up the particles in the object are moving faster • As temperature goes down the particles in the object are moving slower • Finding Thermal energy and AKE

6. Balloon in Flask • The reason this experiment works is because of the kinetic theory of the particles in the flask • As you heat up the flask the molecules begin to move faster (causes them to escape) • You cap the flask with the balloon which traps all of the particles (keeps other particles out) • Put in ice water and the energy decreases which causes the molecules to move slowly and come back together (sucks the balloon in)

7. States of Matter • Matter-Anything that has mass and occupies space • There are 3 common types of matter on earth • Solid, liquid, gas • 4th type of matter is most common and found in stars of our universe • Plasma

8. Solid Matter • In a solid the particles inside the object are packed closer together • These particles have less energy then liquid and gas states • Most solids have a specific geometric arrangement for their particles • Ex-Picture of water on pg 489 of your text book • Solids have a fixed shape and volume

9. Liquid Matter • As temperature increases the particles start moving faster • Eventually they gain enough KE to temporarily move past their boundaries • Slide past each other • More energy then solids but less then gases • Liquid has a fixed volume but not a fixed shape • Solids melt to a liquid at heat of fusion

10. Gas Matter • Gases have enough kinetic energy to overcome all the attractions between the particles • Gases have more energy then liquids and solids • Gases do not have fixed volume or shape • Liquids turn to gases when they hit the heat of vaporization

11. Heating Curve (S to L to G) 1. As you start to heat up a solid the temperature begins to rise 2. The temperature will rise till it reaches the heat of fusion • At this point all energy goes into breaking away from chemical bonds

12. Heating Curve (S to L to G) • Once substance becomes a liquid the temperature begins rising again • Temperature continues to rise until it reaches the heat of vaporization • Once again energy goes into particles breaking its chemical bonds

13. Gas to Liquid • There are two different ways a gas can go to a liquid • Evaporation-One molecule overcomes the attractive forces at a time. • Evaporation is slow enough that you cant see it happen • Boiling-Lots of molecules overcome the attractive forces at a time • Happens with high heat or low pressure

14. Pressure and States of matter • Pressure is the other variable that can affect states of matter • High pressure causes the molecules to stick to be pressed together • Can cause a gas to go to a liquid or a liquid to a solid • Example = Dry ice • Low pressure allows the molecules to spread out • Can cause a solid to go to a liquid or a liquid to a gas • Example boiling cold water

15. Thermal Expansion • Expansion of materials do to rising temperatures • Higher temperature = increase in size of object • Particles move faster/increase distance between • Lower temperature = decrease in size of object • Particles move slower/decrease distance between

16. Diffusion • Movement of molecules from a high concentration to a low concentration • Happens because of the law of entropy • Law of entropy states that everything will go from a state of order to a state of disorder unless energy is added to keep it organized • Will particles diffuse quicker in hot water or cold water?

17. Making Ice Cream • To make ice cream we take a liquid (milk) and other ingredients (for flavor) mix them together and then take away thermal energy • Taking away the thermal energy causes the molecules to slow down, which in turn causes the state of matter to change from a liquid to a solid

18. Materials Needed for making Ice Cream • 1 gallon ziploc bag • 1 quart ziplock bag • 6 cups of ice • 1/3rd cup of salt • 1 cup of whole milk • 1 teaspoon of vanilla or strawberry extract • 2 table spoons of sugar

19. Procedure • Pour milk, extract, and sugar into a small bag (get any extra air out and seal it) • Place small bag in large bag and cover with ice and salt (seal bag) • Shake bag until liquid solidifies • Usually 8-12 minutes

20. Ice Cream Lab • Which type of milk allows ice cream to freeze faster? • Non-Fat or 2% fat