1. Thermal Energy and Heat
Chapter 16
Thermal Energy and Heat
Thermal energy is used to help this locomotive steam along

2. 16.1 Key Concepts
In what direction does heat flow spontaneously?
What causes thermal expansion?
How is a change in temperature related to
specific heat?
On what principle does a calorimeter operate?

3. In the 1700s, most scientists thought that heat was a fluid called calorie that flowed between objects
Count Rumford noticed that when drilling brass canons, heat ______________ when drilling stopped
Rumford concluded that heat could _______ be a kind of matter, but was related to the _______________ of the drill
subsided
not
motion

4. Heat flows spontaneously from ______ objects to _________ objects.
Work and Heat
Heat is the _________________ of thermal energy from one object to another because of a temperature ___________________.
transfer
difference
Heat flows spontaneously from ______ objects to _________ objects.
Think of holding an ice cube in your hand… describe the flow of heat.
warm
cool
Hand  ice cube
(melts)

5. Temperature
Temperature is related to the average _____________ energy of the particles in an object due to their random ______________ through space.
Temperature is a measure of how _______ or ________ an object is compared to a reference point.
On the Celsius scale, the reference points are the
freezing and boiling points of ______________.
On the Kelvin scale, absolute zero is defined as a
temperature of ______ ___________________.
kinetic
motion
hot
cold
water
Kelvin

6. As an object heats up, its particles move _____________, on average.
Temperature
As an object heats up, its particles move
_____________, on average.
Overall, _________________ transfer thermal energy from hot to cold objects.
Thermal energy is the total _____________ and ______________ energy of all the particles in an object.
faster
collisions
kinetic
potential

7. Thermal energy depends on the… ______________ ________________
and _______________ (solid, liquid, or gas) of
an object
mass
temperature
phase

8. Thermal energy depends on mass.
A cup of tea and a teapot full of tea can have the ____________ temperature.
The average kinetic energy of the
particles is the _________ in the cup
and the pot.
There is __________ thermal energy in the teapot because it contains more _______________.
same
same
more
particles

9. Thermal energy depends on temperature.
Compare a cup of hot tea with a cup of cold tea.
In both cups, the tea has the same __________ and _______________ of particles.
The average kinetic energy of particles is higher in the _________ tea, so it has greater thermal energy.
mass
number
hot

10. The tea is at a ____________ temperature than the lemonade.
Thermal Energy
Thermal energy depends on mass and temperature.
The tea is at a ____________ temperature than the lemonade.
The lemonade has more _______________ energy because it has many more ___________
higher
thermal
particles

11. Thermal Contraction and Expansion
Thermal expansion is an increase in the _______________ of a material due to a temperature increase.
volume
Thermal expansion occurs when particles of matter move _________________ apart as temperature increases.
farther

12. If you bring the balloon inside, it ___________
Thermal Energy
If you take a balloon outside on a cold winter day, it _______________ in a process of thermal ________________.
Slower particles collide ________ often and exert less force.
shrinks
contraction
less
If you bring the balloon inside, it ___________
_____________ expand more than liquids and liquids usually expand more than solids.
expands
Gases

13. Thermal Energy
As temperature increases, the alcohol in a thermometer expands, and its ____________ increases in proportion to the increase in temperature.
In an oven thermometer, strips of steel
and brass expand at different rates as
the coil heats up. The coil ____________, moving the needle on the temperature
scale.
height
unwinds

14. Specific Heat
Specific heat is the ______________ of heat needed to raise the temperature of _______ of a material by ________.
amount
1 g
1 °C
The lower a material’s specific heat, the _________ its temperature __________ when a given amount of energy is absorbed by a given mass.
changes
more

15. Specific Heat
Think about going to the beach on a warm summer day…what heats up faster:
the air around you or the water?
the sand or the water?

16. Specific Heat

17. Q is _________ in joules, m is __________ in grams,
Specific Heat
In this formula…
Q is _________ in joules,
m is __________ in grams,
c is __________________ in J/g•°C
ΔT is the _______________________
in degrees Celsius.
heat
mass
Specific heat
change in temperature

18. Calculating Specific Heat
An iron skillet has a mass of grams. The specific heat of iron is J/g•°C. How much heat must be absorbed to raise the skillet’s temperature by 95.0°C?
Q =
(500.0 g)
(0.449 J/g·°C)
(95.0 °C)
Q = 21,300 J

19. A calorimeter is used to measure specific heat.
A ______________________ is an instrument used to measure changes in thermal energy.
A calorimeter is used to measure specific heat.
calorimeter

20. A sample is heated and placed __________ the calorimeter.
Specific Heat
A sample is heated and placed __________ the calorimeter.
The temperature change of the ______________ is observed.
The hot sample will _____________ energy but the water will ____________ it
inside
water
release
absorb

21. What is the difference between temperature and heat?
Assessment Questions
What is the difference between temperature and heat?
Measure of how
hot or cold an
object is
Transfer of thermal energy
(Kinetic energy)

22. What causes a gas to expand when its temperature is increased?
Assessment Questions
What causes a gas to expand when its temperature is increased?
The number of particles increases as temperature increases.
Each particle expands as its temperature increases, so the total volume increases.
As temperature increases, more electrons leave atoms and move separately.
As gas particles move faster, they overcome some forces of attraction.

23. Water has a high specific heat…what does that mean?
Assessment Questions
Water has a high specific heat…what does that mean?
Water requires a large energy transfer to change
is temperature

24. How does a calorimeter work?
Assessment Questions
How does a calorimeter work?
A hot sample transfers energy
to the water…
The temperature change of the
water can be recorded