Chapter 9 Heat & States of Matter

Fun Fact Water is a unique substance. Unlike most materials that expand when heated, water at temperatures of 1, 2, or 3 degrees Celsius contracts when heated. Water is most dense at 4 degrees Celsius. This property allows ice to float in your glass of water and keeps pond from freezing from the bottom up.Water is a unique substance. Unlike most materials that expand when heated, water at temperatures of 1, 2, or 3 degrees Celsius contracts when heated. Water is most dense at 4 degrees Celsius. This property allows ice to float in your glass of water and keeps pond from freezing from the bottom up.

Common Misconception During Cold weather, people often close doors and windows to keep the cold out. Since cold is the absence of thermal energy, they are actually attempting to keep the thermal energy inside, not keep the cold out.During Cold weather, people often close doors and windows to keep the cold out. Since cold is the absence of thermal energy, they are actually attempting to keep the thermal energy inside, not keep the cold out.

What is temperature? The measure of the average kinetic energy of the individual particles in an object. *Remember Kinetic Energy – Energy of motion

What are the three temperature scales? 1)Fahrenheit a)Water freezes = 32 b)Water Boils = 212 2)Celsius a)Water freezes = 0 b)Water Boils 100 3)Kelvin a) Water Freezes = 273 b) Water Boils = 373

Conversions To convert Fahrenheit to Celsius C = 5/9(F – 32) To convert Celsius to Fahrenheit F = 9/5 ( O C) + 32 To convert to Kelvin Add 273 to any temperature in Celsius

Now You Try What is the temperature 86 o F on the Celsius Scale? 5/9( ) = 30 C What is the temperature of 22 o C on the Fahrenheit scale? F = 9/5(22) + 32 = 72 What is 16 degrees Celsius in Kelvin

What is thermal energy? The total energy of all the particles in a substance.The total energy of all the particles in a substance. The sum of the kinetic and potential energy of all the particles in an object.The sum of the kinetic and potential energy of all the particles in an object. Sometimes called internal energy.Sometimes called internal energy. Depends onDepends on –Number of particles in an object –Temp of object –Arrangement of particles

So Far What is temperature? What is thermal energy?

What is the definition of heat? Thermal energy moving from a warmer object to a cooler object.Thermal energy moving from a warmer object to a cooler object. Measured in joules.Measured in joules.

Heat always flows from a warmer object to a cooler object

What is specific heat? The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree celsius.The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree celsius. Measured in J/(Kg o C)Measured in J/(Kg o C)

Review Temperature Thermal Energy Heat Specific Heat