Unit 2 Lesson 4

Monday, September 13, 2010

Opening Instructions

1. Copy the weekly assignments in your agenda. Place your agenda on the corner of your table. Mrs. G or Mr. E will initial and give an entry for today’s drawing.

2. If you earn an entry, put your name on the slip. Write on the slip if the jars of candy are either pure substance or a mixture. Make sure you explain your reasoning!

3. Answer the warm-up questions for today. Place the warm-up sheet in your science section of your binder. Be ready to review answers

TIME LIMIT – 8 MINUTES

Vocabulary Activity

Use the textbooks to find the definitions to the terms on the vocabulary worksheet. Add an example demonstrating how each term is used. The first two terms are completed as an example for you.

TIME LIMIT – 12 MINUTES

Phase Change Review

Points to remember about phase changes:1) As energy is added to a substance, the atoms

or molecules move faster and faster.2) As the atoms or molecules move faster, the

space between the atoms or molecules increases (expansion take place)

3) The amount of matter does not change -- just the motion and spacing

Crushed Can Review

Let’s figure out what happened in our “crushed can” demonstration.

First draw the molecules of water in the can before the can was heated.

Next draw the molecules of water after the can was heated.

Crushed Can Review

Before heating After heating

Air

Air is pushed out by the expanding water vapor

Crushed Can Explanation

The empty can contains air molecules. These molecules inside and outside of the can collide with the metal surface and are in balance. As the water boils inside the can, air molecules (oxygen and nitrogen) are displaced (pushed out) by the water vapor molecules. When the can is inverted into the cold water, a seal is made that prevents air from re-entering; at the same time the water cools the can and causes the water vapor molecules to condense to liquid. With a vacuum inside the can, the air pressure outside crushes the can.

Crushed Can Review

Lastly, draw the molecules of water after the can was put into the cold water. Remember the can was turned upside down so air could not enter the can.

Water here prevents air from re-entering

A vacuum (no particles) develops here Pressure from the

outside air pushes in on the empty part of the can

Four Corners

Decide which of the four corners you will choose (evaporation, condensation, freezing, or melting). You and your seat partner must go to different corners. Write your choice on your notes.

When announced, move to your corner.

Four Corners

Answer the following three questions. 1. What temperature change controls this phase change?2. What do my molecules look like before and after this process? (Draw a picture) 3. If your sample was water, what temperature would this process occur at?

Share your answers with another student in your corner. Be ready to share your answer with the class.

Unit One Retests

Compare the 2nd Opportunity test to your test analysis. Did you miss the same questions?

If you scored below 80%, you may submit a test correction tomorrow! For each missed question:1- Copy the question over2- Give the correct answer with an explanationCORRECTIONS ARE DUE TOMORROW!!!

Twitter Summary

Explain why the soda can was crushed in last week's demonstration in 150 characters or less. (An “out-the-door” activity)