NOTES-Chapter 12

Thermal Energy

• Heat is defined and expressed by the Kinetic Molecular Theory of heat.

•This theory states that all matter is made up of tiny particles which are constantly in motion.

•Heat is the internal energy which is transferred from bodies of higher internal energy to bodies of lower internal energy. Heat does work and work produces heat.

•Temperature and heat are different. Temperature is a measure of the average kinetic energy of the molecules of the substance.

•Temperature is measured with a thermometer due to the expansion & contraction of the liquid in the scale.

•The metric scale is the Celsius scale & it has 2 fixed points:•Freezing point of water•Boiling point of water

•Freezing point is 0 degrees and boiling point is 100 degrees.

Celsius and Fahrenheit can be converted back and forth….

With formulas.

F= C(1.8) + 32

C=(F-32) / 1.8

•The random motion of molecules is thought to approach zero at -273 degrees Celsius----average kinetic energy is zero.

•This temperature is called absolute zero and is measure by the Kelvin scale.

•Celsius can be converted to Kelvin by the following formula:

•K = degrees C + 273

• Heat Travels from hot to cold.

• It travels until it reaches thermal equilibrium.

•The unit of heat measurement is the calorie—it is the amount of heat needed to raise the temperature of 1 gram of water 1 degree Celsius.•Bigger unit is the Kilocalorie.

•Specific Heat of a substance is the amount of heat needed to raise the temperature of a unit mass of that substance through one degree.

•Specific Heat is expressed in cal/g(degreeC)

•And are specific for each type of substance.

•The quantity of heat gained or lost by a mass as it changes temperature is determined by the mass, change in temperature, and specific heat.•H = m c (Delta t)

• States of Matter

Heat Transfer Methods

Insulators and Conductors

Phase Changes

Laws of Thermodynamics