2. Formation of a New Substance Heat and Light, Precipitate, Color Change, Temperature Change, Production of Gas

3. Background Changes in matter happen all around you all the time. You have already learned about physical changes in matter. Examples of physical changes are freezing, melting, and breaking a substance. Physical changes do not change the type of matter. When a chemical change happens a new substance is created. This makes it different from a physical change. Chemical changes can be observed and measured in the laboratory. Observing means not only using your eyes, but other senses as well.

4. Look at these signs of a chemical change: A gas is produced Observe bubbling, fizzing, foaming, or a change in smell.

5. Look at these signs of a chemical change: A precipitate is formed Observe a solid forming when two or more liquids are combined.

6. Look at these signs of a chemical change: Change in energy Observe a temperature change or light released.

7. Look at these signs of a chemical change: The color changes Observe a color change that is not expected.

8. Background Which of your senses can you use to observe these signs in a laboratory? - Senses- Visual: Use your eyes Taste: Use your mouth Audio: Use your ears Smell: Use your nose Tactile: Use your sense of touch Which of your senses should NOT be used in a chemistry laboratory?

9. Background Here are four examples of matter that is changing: Think about the signs of a chemical change and determine if each of these is a physical or chemical change. A burning candle A melting ice cube A rusting nail Crushing a piece of chalk

10. Part I: Plan Your Investigation 1.My Question of Inquiry: What signs of a chemical reaction can be observed when different chemicals are combined?

11. Part I: Plan Your Investigation 2. What do you need to do to answer this Question? I need to look for evidence that a chemical reaction has occurred when different substances are combined. Some evidence I can look for is gas production, color change, temperature change, and formation of a precipitate.

12. Part I: Plan Your Investigation What safety precautions must you take in these investigations? Goggles, should be worn at all times during the investigation. Do not eat or drink any of the chemicals. Clean up spills immediately. Caution with fire. Wash your hands.