16.1 Thermal Energy and Matter
In the 1700s, most scientists
thought heat was a fluid called
___________.
Count Rumford (Benjamin
Thompson) supervised the drilling
of brass cannons in a factory in
Bavaria.
From his observations, Rumford
concluded that heat is not a form
of ______, but was related to the
motion of the drill.
16.1 Thermal Energy and Matter
Work and Heat
A drill is a machine that does work on the cannon. No
machine is 100% efficient. Some work done by the drill is
useful, but some energy is lost due to friction.
Heat flows from the cannon to a surrounding water
because the cannon is at a higher temperature than the
water.
• ________: the transfer of thermal energy from one
object to another because of a temperature
difference.
• Heat flows spontaneously from______objects to
__________objects.
16.1 Thermal Energy and Matter
Temperature
• Temperature: a measure of how hot or cold
an object is compared to a ____________point.
• On the Celsius scale, the reference points are the
freezing and boiling points of water.
• On the Kelvin scale, absolute_____is defined as
a temperature of 0 Kelvin.
•Temperature is related to average kinetic
energy of particles due to random motions
through space.
16.1 Thermal Energy and Matter
Temperature
As an object heats up, its particles move faster
 The average_______energy of the particles
and the___________________increase.
• Heat can flow by the transfer of energy in
collisions.
• Overall, collisions transfer thermal energy from
hot to cold objects.
16.1 Thermal Energy and Matter
Thermal Energy
• Thermal energy: total_________and kinetic
energy of all the particles in an object.
• Depends on the mass, temperature, and
phase (solid, liquid, or gas) of an object.
16.1 Thermal Energy and Matter
Thermal Energy
_______: a cup of tea and a teapot full of tea can have
the same temperature.
• The average kinetic energy of the particles is the same in
the cup and the pot.
• There is more thermal energy in the teapot because it
contains more particles.
____________: compare a cup of hot tea with a cup of
cold tea.
• In both cups, the tea has the same mass and number of
particles.
• The average kinetic energy of particles is higher in the hot
tea, so it has greater thermal energy.
16.1 Thermal Energy and Matter
Thermal Energy
Thermal energy depends on mass and temperature.
A. The tea is at a higher temperature than the
lemonade.
B. The lemonade has more thermal energy because it
has many more particles.
16.1 Thermal Energy and Matter
Thermal Contraction and Expansion
• Thermal___________: increase in the volume
of a material due to a temperature increase.
•Particles of matter move farther apart as
temperature increases.
16.1 Thermal Energy and Matter
Thermal Energy
If you take a balloon outside on a cold winter day, it
shrinks in a process of thermal _______________.
– As temperature decreases, the particles of the air inside
the balloon move more ___________, on average.
– Slower particles collide less often & exert less force.
– Pressure decreases and the balloon contracts.
– If you bring the balloon inside, it expands.
• _____ expand more than liquids and liquids usually
expand more than __________.
16.1 Thermal Energy and Matter
Thermal Energy
As temperature increases, the alcohol in a
thermometer expands, and its height 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
unwinds, moving the needle on the temperature
scale.
16.1 Thermal Energy and Matter
Specific Heat
• Specific heat: the amount of heat needed to raise
the temperature of one gram of a material by one
________________________.
• The lower a material’s specific heat, the _______ its
temperature rises when a given amount of energy is
absorbed by a given mass.
• When a car is heated by the sun, the temp. of the metal
door increases more than the temp. of the plastic bumper.
•The iron in the door has a lower specific heat than the
plastic in the bumper.
16.1 Thermal Energy and Matter
Specific Heat
16.1 Thermal Energy and Matter
Specific Heat
In this formula, heat is in Joules, mass is in grams,
specific heat is in J/g•°C, and the temperature change
is in °C.
16.1 Thermal Energy and Matter
Specific Heat
Calculating Specific Heat
An iron skillet has a mass of 500.0 grams. The
specific heat of iron is 0.449 J/g•°C. How much
heat must be absorbed to raise the skillet’s
temperature by 95.0°C?
16.1 Thermal Energy and Matter
Specific Heat
1. How much heat is needed to raise the
temperature of 100.0 g of water by 85.0°C?
16.1 Thermal Energy and Matter
Specific Heat
2. How much heat is absorbed by a 750-g iron skillet
when its temperature rises from 25°C to 125°C?
16.1 Thermal Energy and Matter
Specific Heat
3. In setting up an aquarium, the heater transfers
1200 kJ of heat to 75,000 g of water. What is the
increase in the water’s temperature? (Hint: Rearrange
the specific heat formula to solve for ∆T.)
16.1 Thermal Energy and Matter
Specific Heat
4. To release a diamond from its setting, a jeweler
heats a 10.0-g silver ring by adding 23.5 J of heat.
How much does the temperature of the silver
increase?
16.1 Thermal Energy and Matter
Specific Heat
5. What mass of water will change its temperature by
3.0°C when 525 J of heat is added to it?
16.1 Thermal Energy and Matter
Specific Heat
• A calorimeter is an instrument used to measure
changes in____________energy.
• Heat flows from a hotter object to a colder object
until both reach _________________temperature.
• According to the law of conservation of energy, the
thermal energy released by a test sample is equal to
the thermal energy absorbed by its surroundings.
• The calorimeter is sealed to prevent thermal energy
from escaping.
16.1 Thermal Energy and Matter
A calorimeter is used to measure________
heat. – (Hint: This would be a great essay!)
1) A known mass of water is added
2) The mass of the sample is measured.
3) The sample is heated, placed in the water,
and the calorimeter is sealed.
4) The temperature change is measured.
5) Thermal energy absorbed by the water is
calculated using the specific heat equation.
6) Since the same amount of thermal energy
was given off by the sample, the specific heat
of the sample can be calculated.