Name: _____________________________________ Date: _______________

Energy Forms and Changes

Directions: Update your TOC. Page 121 will be called “Energy Forms and Changes”. If you have already written on this page, use 121b. Take notes on the content below until you react today’s assignment at the “Introduction Section”. Copy these notes word for word in your notebook.

• Exothermic changes occur when energy is released to the environment• An example of an exothermic change is water freezing since it releases its heat to the

environment so that it can freeze• the system loses heat as the surroundings heat up

• Endothermic changes occur when energy is absorbed from the environment• An example is water melting since it gathers as much heat as possible from the

environment to melt• heat is needed by the reaction, so it draws heat from its surroundings, making them

feel cold• Catalyst: increases the rates of the reaction without changing the chemistry of the reaction. It can

be recovered completely at the end of the reaction, intact.

Energy Diagram

In order for the reaction to occur Activation Energy needs to be reached.• Activation energy (E a) = minimum amount of energy to start a reaction. • The more energy needed to start a reaction, the higher the activation energy.

1

Name: _____________________________________ Date: _______________

At the end of the reaction there are products with certain energy

∆H = difference in energy of reactants & productsIf H is positive the reaction is EndothermicΔ If H is negative the reaction is ExothermicΔ

END NOTE TAKING HERE.

H: heat of reactionThis shows negative and is there fore exothermic. The products are lower than the reactants.

2

Name: _____________________________________ Date: _______________

TODAY’S ASSIGNMENT: WRITE DIRECTLY ON THIS WORD DOCUMENT. You can turn it in with TEAMS OR if you need to email this document to me.

Introduction

In this activity you will investigate the flow of energy in a system. You will observe how energies are transferred and changed as they move along in a system. If the link doesn’t work search “Phet” and you will find the website shown below.

1. Click this link: http://phet.colorado.edu/This is a screen shot of the website:

2. Click the “Play with sims” button.3. In the search section type in: “Energy Forms and Changes”->Click “Run Now!”

If it asks you to download it, go ahead.

4. It will take time to load and then this screen appears:

3

Name: _____________________________________ Date: _______________

Exploration Phase

1. Click the “Intro” tab on the sim.

2. Explore by placing the iron onto the platform to the right of your screen.

3. Click on “Energy Symbols” on the top right of your screen. Keep this checked at all times to “see” the energy in each object.

Energy is the ability to do work. The type of energy we are looking at here is called “thermal” energy.

4. Freely explore by heating or cooling the iron. Use the thermometer to check the temperature of the object.

5. Place a thermometer in the container of water. Notice the temperature of the water.

6. Place the iron back in the container of water. Observe what happens to the temperature of the water. Also, observe what happens to the energy in the water and the object.

Questions

1. What does temperature measure? a. Hint : What happens to the amount of Energy Symbols and the temperature as you heat the

object? b. As you cool the object?

4

Name: _____________________________________ Date: _______________

2. What happens when you heat the brick and place it into the container of water? Use the word temperature and thermal energy in your response to help describe the energy flow.

3. What happens when you cool the brick and place it into the container of water? Use the word temperature and thermal energy in your response to describe the energy flow.

4. Place the water container directly onto the platform and heat the water. Starting from the flame, describe the energy flow.

Note: Some energy seems to be “flowing” away from the water container. How might you explain this? Where is the energy going? Is it disappearing?

5

Name: _____________________________________ Date: _______________

5. Now, cool the water. Starting from the ice cubes, describe the energy flow.

6. Create an endothermic energy diagram and an exothermic energy diagram by going into the “insert” and click on “shapes”. Use the “Draw Text Box” to label your axis and graph.

7. Determine when you have seen an endothermic and exothermic reaction and list your answers below.

Explanation Phase

5) Create a rule that describes how energy is transferred from one object to another in a system.

Click on the “Energy Systems” tab and make the screen look like this:

6) List the different forms of energy that are represented in this simulation:

6

Name: _____________________________________ Date: _______________

7) Turn the faucet all the way on by moving the blue arrow to the right. The water should move the turbine or generator. This should in turn direct energy to the receiver, the container of water. Describe the energy flow in this system.

The water from the faucet produces _________ energy. This turns the turbine, which creates ____________ energy. This _______________ energy causes the water to ___________, creating ___________ energy as an output.

Concept: This is a description of energy flow or transfer , the exchange of energy between objects in a system. In this exchange, energy can take different forms.

8) Complete the table below based on the given parts to explore how energy is transferred within different systems.

Energy Source Generator Receiver Description of Energy Transfer

FaucetThe water from the faucet produces ______________________ energy. This turns the turbine, which creates _________________ energy. This _______________ energy causes the water to ___________, creating ______________ energy as an output.

Solar EnergyThe ______ produces ___________ energy. This is absorbed by the solar panel, which creates _________________ energy. This _______________ energy causes the light bulb to light up, creating ______________ energy as an output.

Tea Kettle Steam The ___________ produces ___________ energy. This turns the turbine, which creates _________________ energy. This _______________ energy causes the water to ____________, creating ______________ energy as an output.

7

Name: _____________________________________ Date: _______________

Cyclist The __________ produces ___________ energy. This turns the turbine, which creates _________________ energy. This _______________ energy causes the light bulb to light up, creating ______________ energy as an output.

9) Why does the cyclist need to be fed?

10) Return to the solar panel system. What happens when you increase the amount of clouds?

Application Phase

11) Using what we’ve learned form this sim, determine what type of energy is shown in each row.

Type of Energy:

a)

8

Name: _____________________________________ Date: _______________

__________________________________

b)

__________________________________

c)

___________________________________

d)

____________________________________

12) Take a look at the picture below. Explain the transfer of energy you see in this system.

________________________ _______________________

______________________ _______________________

Conclusions: Scientists say that “energy cannot be created or destroyed.” What does this mean to you? Share your thoughts with your partner.

Finished: Congratulations! You’ve got the power (energy!)

9