CHAPTER 3 3.2 Heat and Thermal Energy Temperature Energy and
Heat Slide 2 2 3.2 Heat and Thermal Energy We know now that heat is
not the same thing as temperature. Slide 3 3 3.2 Heat and Thermal
Energy We know now that heat is not the same thing as temperature.
Measured in o F, o C, K Slide 4 4 3.2 Heat and Thermal Energy We
know now that heat is not the same thing as temperature. Measured
in o F, o C, K Measured in ? Slide 5 5 3.2 Heat and Thermal Energy
Heat can be measured in joules (J). The joule is the fundamental SI
unit of energy and heat. Slide 6 6 3.2 Heat and Thermal Energy Heat
can be measured in calories. It takes 1 calorie to raise 1 g of
water by 1 o C. 1 Calorie = 1 kilocalorie = 1,000 calories Slide 7
7 3.2 Heat and Thermal Energy Heat can be measured in British
thermal units (BTU). Slide 8 8 3.2 Heat and Thermal Energy joules
(J) calories British thermal units (BTU) Heat can be measured in 1
calorie = 4.184 joules 1 BTU= 1,055 joules Slide 9 9 3.2 Heat and
Thermal Energy second law of thermodynamics: energy (heat)
spontaneously flows from higher temperature to lower temperature.
Slide 10 10 3.2 Heat and Thermal Energy SURROUNDING Slide 11 11 3.2
Heat and Thermal Energy Slide 12 12 3.2 Heat and Thermal Energy
Slide 13 13 3.2 Heat and Thermal Energy first law of
thermodynamics: energy can neither be created nor destroyed. Slide
14 14 3.2 Heat and Thermal Energy The energy inside an isolated
system is constant. The energy lost by a system must be gained by
the surroundings or another system. first law of thermodynamics:
energy can neither be created nor destroyed. Slide 15 15 3.2 Heat
and Thermal Energy Slide 16 16 3.2 Heat and Thermal Energy What
happens when hot and cold water are not allowed to mix but are
allowed to exchange energy? Does one side stay hot and one side
stays cold? Slide 17 17 3.2 Heat and Thermal Energy Thermal
equilibrium Slide 18 18 3.2 Heat and Thermal Energy Same energy
input Different temperature change Slide 19 19 3.2 Heat and Thermal
Energy Specific heat of water: 4.184 J/(g o C) Specific heat of
gold: 0.129 J/(g o C) specific heat: the quantity of energy it
takes per gram of a certain material to raise the temperature by
one degree Celsius. Slide 20 20 3.2 Heat and Thermal Energy One
reason is: Why do different metals have different specific heats?
Slide 21 21 3.2 Heat and Thermal Energy A metal-working process
needs to heat steel from room temperature (20 o C) to 2,000 o C. If
the mass of steel is 100 g, how much heat is required? Slide 22 22
3.2 Heat and Thermal Energy A metal-working process needs to heat
steel from room temperature (20 o C) to 2,000 o C. If the mass of
steel is 100 g, how much heat is required? Asked:Quantity of heat
Given:100 g of steel, temperature difference is 2,000 o C 20 o C
Relationships: Slide 23 23 3.2 Heat and Thermal Energy A
metal-working process needs to heat steel from room temperature (20
o C) to 2,000 o C. If the mass of steel is 100 g, how much heat is
required? Asked:Quantity of heat Given:100 g of steel, temperature
difference is 2,000 o C 20 o C Relationships: Solve: Answer:It
takes 93,060 joules to raise the temperature of 100 g of steel to
2,000 o C, assuming no heat gets lost during the process (which is
not a very good assumption!). Slide 24 24 3.2 Heat and Thermal
Energy A mass of 300 grams of water at 80 o C cools down to 20 o C.
Assume all the heat from the water is absorbed by 100 m 3 of air (a
small room) with a mass of 100,000 g. What is the temperature
change in the air? Slide 25 25 3.2 Heat and Thermal Energy Asked:
Temperature change in o C Given:300 g of water [c p = 4.184 J/(g o
C)], change of 60 o C (80 o C 20 o C), and 100,000 g of air [c p =
1.006 J/(g o C)] Relationships: A mass of 300 grams of water at 80
o C cools down to 20 o C. Assume all the heat from the water is
absorbed by 100 m 3 of air (a small room) with a mass of 100,000 g.
What is the temperature change in the air? Slide 26 26 3.2 Heat and
Thermal Energy Asked: Temperature change in o C Given:300 g of
water [c p = 4.184 J/(g o C)], change of 60 o C (80 o C 20 o C),
and 100,000 g of air [c p = 1.006 J/(g o C)] Relationships: Solve:
A mass of 300 grams of water at 80 o C cools down to 20 o C. Assume
all the heat from the water is absorbed by 100 m 3 of air (a small
room) with a mass of 100,000 g. What is the temperature change in
the air? Slide 27 27 3.2 Heat and Thermal Energy Asked: Temperature
change in o C Given:300 g of water [c p = 4.184 J/(g o C)], change
of 60 o C (80 o C 20 o C), and 100,000 g of air [c p = 1.006 J/(g o
C)] Relationships: Solve: Answer:The air in the room gets warmer by
about 0.75 o C. A mass of 300 grams of water at 80 o C cools down
to 20 o C. Assume all the heat from the water is absorbed by 100 m
3 of air (a small room) with a mass of 100,000 g. What is the
temperature change in the air? Slide 28 28 3.2 Heat and Thermal
Energy conduction: the flow of heat energy through the direct
contact of matter. Slide 29 29 3.2 Heat and Thermal Energy Would
you describe the glass of the test tube as a thermal conductor or a
thermal insulator? Slide 30 30 3.2 Heat and Thermal Energy Would
you describe the styrofoam cup of the test tube as a thermal
conductor or a thermal insulator? Slide 31 31 3.2 Heat and Thermal
Energy Temperature is measured in: o F, o C, kelvin Heat is
measured in: joules (J), calories, British thermal units (BTU)
first law of thermodynamics: energy can neither be created nor
destroyed. second law of thermodynamics: energy (heat)
spontaneously flows from higher temperature to lower
temperature.
