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Let's Get Physical

A substance is a type of matter. For example, water is the substance. When you add cocoa to water, it makes hot chocolate, another substance. Hot chocolate is a substance that you drink on cold winter mornings.

A property is a feature of a substance. For example, a property of water is that it is a liquid at room temperature. Another property of water is that it freezes at zero degrees Celsius. Finally, water will boil and become a gas at 100 degrees Celsius at sea level. Properties of hot chocolate are its warm temperature and sweet taste.

What a state!

One way to describe the physical properties of a substance is to identify its form, or state. The three states (or forms) of matter are:

  • solid
  • liquid
  • gas

 The air we breath is a gas. The water we drink is a liquid. The desk you sit at is a solid. Many types of matter can exist in more that one state. Water is a unique substance because on Earth it naturally exists in all three states.

Each form or state of matter is different. The molecules in a solid, liquid and gas move at different speeds and are “packaged” differently. For example, the molecules in a solid are tightly packed together, while the molecules in a gas move about much more freely.

Explore this by draging your mouse over each picture below. You will see a model of how the particles of each state of matter are moving. Watch closely for differences! 

 

Solid
Liquid
Gas

Home Activity

Changing the state of matter ...
or making ice cream

Materials

  • 2 cups of sugar
  • 4 cups half and half
  • 2 teaspoons of vanilla
  • 1/2 teaspoon of salt
  • Plastic gallon jug with a lid
  • Crushed ice
  • 1/4 cup salt
  • Spoons
  • Cups
  • One large re-sealable bag
  • One small re-sealable bag

*Be sure to have an adult help you with this activity

Note: This activity is more fun when done with a family member or friend. Write down what the liquid looks like before you put it in the ice. Describe what the liquid looks like after it has changed.

Procedure:

  1. Put the sugar, half and half, vanilla, and the salt in the gallon jug. Place the lid on the jug and shake well to make sure all of the ingredients mix.
  2. Put some of the mixture in your small re-sealable bag. Be sure to seal the bag well and do not overfill.
  3. Now take your large re-sealable bag and fill it half way full of ice.  Put your small bag full of the ice cream mixture inside of the large bag with the ice.
  4. Place the 1/4 cup of salt over the ice and then seal the large bags.

*STOP*  It is time to make a hypothesis.  How long do you think it will take to freeze the ice cream? (In other words, how long will it take for the liquid ice cream mixture to change state to a solid?)

  1. Slowly move the large bag back and forth in your hands. (Watch out ... this is COLD!)
  2. When the ice cream is frozen, remove it from the bags.
  3. Serve and enjoy!

While eating your ice cream, analyze your results, was your hypothesis correct?

Analysis:

  1. Would adding more ice make the mixture freeze faster?
  2. How do you think the salt affects the freezing time?

 

Get the plug-ins: Get Adobe Acrobat Reader , and Get Quicktime Player. (The QuickTime plug-in is needed to play sounds and movies correctly.)

Want to share photos of you or your friends doing this activity? Send it in an e-mail with the following information:

  1. The title of the activity
  2. The URL (Internet address)
  3. Your name.
Remember that no pictures can be used that show student faces or student names on it. 

Teachers should view the Teacher Site Map to relate Sci-ber text and the USOE 5th grade science core.


Updated October 24, 2008 by: Glen Westbroek

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