Kinetic Molecular Theory

1
Kinetic Molecular Theory

• All matter is made of molecules
• These are always in motion
• Their motion is directly related to temperature
• Click for Demo

2
Heat Defined

• Heat is a form of energy
• It is caused by the motion of molecules
• Give credit to Count Rumford
• Link on Rumford

3
(No Transcript)
4
Heat Transfer

• Heat moves from hot to cold.
• It can do this through
• Conduction
• Convection
• Radiation

5
Conduction
When there is direct contact between objects and
heat is transferred.
6
Convection
When there is transfer of heat in fluids The hot
fluid rises, due to its lower density
7
Convection Cells
8
Radiation
When heat moves as an electromagnetic wave
9
Temperature Versus Heat

• Temp. is a measure of the average velocity of the
  molecules
• Heat is a form of energy caused by this motion

10
More

• ..the higher the temperature, the more energy
  something has
• But
• temperature is NOT a measure of the amount of
  heat

11
Measuring heat

• Heat is measured in calories
• A calorie is 4.19 joules
• A calorie is how much heat is needed to get one
  gram of water to go up one degree Celsius.

12
Think about this

• You have a swimming pool that is 10º C
• You have a cup of hot cocoa
• Which has a higher temperature?
• Which has more heat?

13
Temperature Versus Heat

•  Heat total energy
• Temperature average energy

14
Temperature Scales

•  Fahrenheit
• Celsius
• Kelvin
• link
• Ab zero
• Bases

15
Specific Heat

• The amount of heat needed to raise 1 gram of a
  substance by 1 C
• Unit cal / g C
• Water is easy, it is1 cal / g C

16
Calorimeter

• A device to measure heat
• All you do is measure water and see how much it
  goes up in temperature

17
Calorimeter

• The heat lost by an object is gained by the
  water in the calorimeter
• Equation for Heat lost or gained
• Mass x ?T x specific heat