Download Key p.4-12, p.14-18

Lesson 1: Kinetic Molecular Theory, Temperature, and
Thermal Energy
** Think, Pair, and Share**
What is same about ice, liquid water, and water vapour?
What is different? Can you describe the motion of water
molecules in these three states?
Kinetic Molecular Theory
The kinetic molecular theory (KMT) has two main principles:
1) All matter is made up of particles that are moving.
2) The more kinetic energy the particles have, the
faster they move.
Using kinetic energy to describe the three states of matter:
Solids:
 Particles are very close to each other. Their movement is limited.
Liquids:
 Particles are still close to each other, but they have enough energy to
slide past one another.
Gases:
 Particles are relatively far apart, and will fill the volume they occupy.
**Can you label the solid, liquid, and gas in the picture below?**
From Left to Right: Liquid, Gas, Solid
Temperature
Temperature is defined as the average kinetic energy of a substance.
Temperature is measured using a thermometer.
Temperature can be measured on three different scales:
Degrees Celsius:
In degrees Celsius, water freezes at 0 °C, and boils at 100 °C.
The Celsius scale is based on the freezing and boiling points of water, with
100 degrees separating the two.
Degrees Fahrenheit:
In degrees Fahrenheit, water freezes at 32 °F, and boils at 212 °F.
The Fahrenheit scale is based on the freezing and boiling points of water,
with 180 degrees separating the two.
Kelvin:
Kelvin is based on the kinetic energy of particles in a substance.
Therefore at 0 K, particles will have zero motion.
*Note: we do not say degrees Kelvin like with Celsius and Fahrenheit. For
example we would just say 300 Kelvin.
Converting between Temperature Scales:
Kelvin = °C + 273
°F = (°C x 1.8) + 32
**Can you rearrange both
formulas above to solve for °C?**
°C = Kelvin - 273
°C = (°F – 32)
1.8
**Let’s Practice! Remember to show your work**
1) Convert 22°C to degrees Fahrenheit? 71.6 °F
F = (22 X 1.8) + 32 = 71.6 °F
2) How many degrees Celsius is 54°F? 12.2 °C
C = 54 -32 = 12.2°C
1.8
How many degrees Celsius is 385 K? 112 °C
C = 385 -273 = 112°C
3) What temperature does water boil in Kelvin? 373 K
K =100 + 273 =373K
4) How many Kelvin is 300°F? 421.9 K
°C = 300 -32 = 148.9°C
1.8
K = 148.9 + 273 = 421.9K
Thermal Energy
Thermal energy is the total energy of all the particles in a substance.
Total energy includes both kinetic energy (energy of motion) and potential
energy (stored energy).
**Complete the formula below**
Total Energy = (kinetic energy + potential energy) x (#particles)
**What would have more thermal energy, a cup of hot chocolate at
60°C or Elk Lake?**
Elk Lake: it has lots of particles compared to hot chocolate cup
Lesson #1 Worksheet
1. On a cold day you can see your breath. This is water vapour
condensing in the cold air to form little droplets of water. Describe the
motion of the particles as they go from the gas to liquid state using
KMT.
Particles are relatively far apart and move freely. Then they lose
thermal energy as they come into contact with the air. The particles
moves closer together and slide past each other.
2. Before you leave for school you place a block of frozen soup in a pot to
melt for dinner that night. Describe the motion of the particles as they
go from the solid to liquid state using KMT.
The particles are very close together with limited motion. As they gain
thermal energy from the surroundings, the particles move faster and
slide past one another to become a liquid
3. Explain using KMT, why dishes dry if you leave them on the rack
overnight.
If you wait long enough all the particles will eventually enter the
gaseous state.
4. Your American friend is having trouble understanding why you are
saying 30 degrees is a hot day. Can you explain the problem?
Americans use the Fahrenheit scale so they think you mean 30°F
which is –1.1°C, but you mean 30°C which is 86°F.
5. What temperature does water freeze and boil in Kelvin?
Freeze: 273 K Boil: 373 K
6. Why are you unable to melt a large ice sculpture with one match?
The ice sculpture has more thermal energy. Despite its temperature, it
has more particles.
Lesson 2: Heat
Heat is the transfer of thermal energy from one substance to another due to
their differences in temperature.
**What is meant by the terms heating and cooling?**
Heating is adding thermal energy, cooling is removing thermal energy.
Objects cannot absorb cold. Only lose heat!
Thermal energy can be transferred in three ways:
1) Conduction
2) Convection
3) Radiation
Conduction
Conduction is the transfer of thermal energy within an object or between
objects due to a difference in their temperature.
Energy is always transferred from the object with more thermal energy to
the one with less thermal energy
*Note: Conduction also occurs within an object.
**Can you think of some examples of conduction?**
handle of a cooking pot, soup spoon, etc.
Convection
Convection is the transfer of thermal energy through the movement of
particles within a fluid.
*Note: A fluid means liquids and gases!
**Can you think of any examples?**
Hot air rising from a heater, convection oven
Why does hot air rise?
Thermal expansion is an important concept in convection.
When particles gain kinetic energy, they move faster and further apart.
The same substance now occupies more volume. Therefore, its density has
decreased.
Less dense substances rise while more dense substances sink.
Radiation
Radiation is the transfer of thermal energy using electromagnetic waves.
These electromagnetic waves can be absorbed and reflected.
An object gets warmer when it absorbs electromagnetic waves.
**Can you think of any examples?**
sun, radioactive decay
Electromagnetic spectra
Conserving Thermal Energy
Objects that prevent the loss of thermal energy are known as insulators.
Objects that are good insulators, are bad conductors
Conversely, object that are good conductors are bad insulators.
**Can you think of any examples**
Styrofoam: conductor
air, asbestos: insulators
Heat Capacity
Heat capacity refers to the amount of thermal energy needed to raise the
temperature of 1kg of substance by 1 degree Celsius.
**Using the table to the right,
would it require more energy to
heat 1kg of aluminum by 1 degree
Celsius or 1 degree of diamond?**
Aluminum
Latent Heat
Latent heat is the amount of thermal energy required to bring about a phase
change, without actually changing the temperature of the substance.
Water has a relatively high values of latent heat.
**What are some of the exception thermal properties of water we
discussed? Can you think why these properties might be useful to us as
humans?**
- high latent heat
- high specific heat capacity
it requires a lot of thermal energy to change the temperature of water,
which is good because water helps regulate our body temperature
Lesson #2 Worksheet
1. In each example, state whether convection, conduction, or radiation is
occurring.
a. A spoon starts to feel warm after sitting in a hot bowl of soup.
conduction
b. A burrito is warmed in the microwave radiation
c. Macaroni noodles rise and fall in a pot of hot water. convection
d. A cup of coffee is too hot to pick up. conduction
e. You go tanning at the beach. radiation
f. The basement of your house feels cooler compared to the
upstairs. convection
2. A runner asks you to “hand them an ice cube so they can absorb the
cold” after a long race. How would you correctly rephrase statement?
cold cannot be absorbed. The runner should say he is trying to lose
some thermal energy.
3. Describe three situations where you might use insulation.
windows, keeping a meal or coffee hot, oven mitts.
4. Explain how a hot air balloon works.
The hot air in the balloon spreads apart and becomes less dense than
the outside air. Warm air rises as it is lighter then the surrounding air.
Components of the Earth’s Surface
The Earth’s surface can be divided into three components:
1) Lithosphere
2) Hydrosphere
3) Atmosphere
Lithosphere
The solid outer layer (100km) of Earth’s crust.
The lithosphere contains many inorganic rocks and minerals.
Hydrosphere
The hydrosphere is made up of all the water in, on, or near Earth’s surface.
**How much of the hydrosphere is fresh water?**
3% where 2% is frozen in glaciers
Atmosphere
The atmosphere is made up of gases surrounding Earth (about 500km
thick).
**What gases are most abundant in our atmosphere?**
Nitrogen, N2: 78%,
Oxygen, O2: 21%
Sources of Thermal Energy on Earth
Solar Radiation
Radiation from the sun provides about 90% of the thermal energy that
warms the lithosphere, hydrosphere and atmosphere.
Approximately 30% of solar radiation is reflected back to space.
Approximately 70% of solar radiation is absorbed by the Earth
**What objects might absorb solar radiation? What objects might reflect
solar radiation**
Bright, shiny objects reflect. Dark and dull objects absorb.
The ability of an object or surface to reflect light or solar radiation is called
albedo.
**Why does fresh snow have
a better albedo than old
snow?**
It is more dull and dark than
fresh snow.
Heat of Formation
Earth formed due to the gravitational attraction of large chucks of matter.
These high-speed collisions and the gravitational pressure release thermal
energy.
Radioactive Decay
Some elements on Earth release radiation in order to become stable.
**What makes an element radioactive?**
Extra neutrons in its nucleus
Earth’s surface
The thick outer layer of Earth’s crust prevents the loss of thermal energy so
it can be thought of as an insulator.