Earth and Space Science:Energy Transfer in Natural

Systems

What is climate change?

How can I reduce my carbon footprint?

How does heat transfer cause weather?

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 °FF = (22 X 1.8) + 32 = 71.6 °F

2) How many degrees Celsius is 54°F? 12.2 °CC = 54 -32 = 12.2°C

1.8How many degrees Celsius is 385 K? 112 °CC = 385 -273 = 112°C

3) What temperature does water boil in Kelvin? 373 KK =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. convectiond. 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 EarthSolar RadiationRadiation 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 havea better albedo than oldsnow?**

It is more dull and dark thanfresh 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.