Chemical Changes and Physical Changes Objective: The student will identify evidence of chemical changes through color, gas formation, solid formation, and temperature change.

Testing a Tablet Suppose you read about a mysterious material beneath the Antarctic icecap that has been discovered by scientists. How would you learn about such a material? A chemist would study it to learn about its chemical and physical properties. You can do the same thing.

Materials Goggles Mystery tablet Test tube Water Sheet of black construction paper Hand lens Small plastic jar Match Science notebook

Procedures Observe the tablet carefully. Record in your Science Notebook any properties you can observe just by looking at the tablet and handling it. Then break the tablet into four pieces of about the same size. Add one piece of the tablet to a test tube half full of water. Observe what happens and record your observations in your Science Notebook.

Procedures cont. Hold the bottom of the test tube in one hand. Cover the opening of the test tube with your thumb. Describe what you feel. Place a piece of the tablet on a sheet of black paper and crush it. Examine the small pieces carefully with a hand lens. Describe what you see.

Procedures cont. Place another piece of the tablet in a small jar and add a small amount of water. Have your teacher light a match for you. While the tablet is still reacting, dip the flame into the beaker, keeping it above the surface of the liquid. Observe what happens and record your observations.

Analyze and Conclude Describe what happened when the tablet was added to water. Describe how the tablet changed during a physical change? Describe how the tablet changed during a chemical change? In step 3, how did the bottom of the test tube feel? What did you feel with your thumb? What can you infer about the gas that was produced during the reaction? Give evidence to support your inference. Make a list of the physical and chemical properties of the tablet. What do you think the tablet might be?

Changes Question: If I mix substance A with substance C and/or substance B with substance C, will there be a chemical change? Hypothesis: If I mix substance A with substance C and/or substance B with substance C, then I think there will be a chemical change because …

Materials 1 canister with substance A 1 canister with substance B 1 medicine cup with substance C 1 Zip-lock bag Paper towels Safety goggles Science Notebook

Procedures Place substance A into one corner and substance B into the other corner of a zip-lock bag. Carefully place the cup in the bag. Keep it upright! Zip the bag closed. Tilt the cup over so that substance C spills into the bag. Observe. Feel the outside of the bag. What type of change do you think occurred? Why? Write down any evidence of a chemical change.

Conclusion When I mixed substance A with substance C and substance B with substance C, a ______________ did occur. The bag expanded and a gas was produced. There was also a temperature change and a color change.

Vocabulary Physical property – a characteristic that can be measured or detected by the senses. Chemical property – the ability or tendency of a material to change its chemical makeup. Physical change – a change in the size, shape, or state of matter with no new matter being formed. Chemical change – a change in matter that results in new substances being formed.