1. Physical and Chemical Properties and Changes

2. Objective and essential question
Objectives: SWBAT distinguish between physical and chemical changes and properties. Essential Question: What are the properties that classify a physical or chemical change? In what ways is a chemical change different from a physical one?

3. Physical Properties Describes how the substance looks/feels, etc
Examples: melting point, color, mass, luster (shine), hardness, temperature

4. Particle Picture: Physical Changes
Definition:
Change the appearance, not the substance or chemical composition
Examples: Hair cut, state change (melting), sugar cube dissolving

5. Particle Picture: chemical Changes
Definition:
Produces a new substance (changes chemical composition)
Involves a chemical reaction
Examples: fireworks, rust, burning coal, baking bread

6. Chemical Properties and changes
Examples:
Describes how a substance reacts
Substance has to chemically change to observe it
Examples: chemical stability, flammability, ability to oxidize or react

7. Observable factors of a chemical Change
Precipitate Formation
Light or Heat Released
Gas Formation
Color Change

8. Summary: Physical vs. chemical changes
Physical Change
Chemical Change
Does not involve changes in identity of a substance
Change the (chemical) identity of the substance
Cause a change in state or shape
Involves a chemical reaction, Causes a change on a particle level

9. Sample Test Question
Which process involves a chemical change?
melting of ice
boiling of water
freezing of water
decomposing of water (H­2O) into H and O

10. Which process involves only (a) physical change(s)?
Sample Test Question
Which process involves only (a) physical change(s)?
Burning gasoline
Reacting hydrochloric acid with ammonia
Combining hydrogen and oxygen to form water (H2O)
Melting barium

11. Mixing two kinds of paint produces a physical change because:
Sample Test Question
Mixing two kinds of paint produces a physical change because:
A new substance is formed and the color changes
The color may change, but no new substance is formed
A new liquid is formed (different color paint)
This is not a physical change. It is a chemical change.

12. Which of the following always takes place in a chemical reaction?
Sample Test Question
Which of the following always takes place in a chemical reaction?
A new product (substance) forms
The temperature increases
The mass of the product changes
A gas forms

13. Sample Test Question
Given the particle diagram: Which particle diagram best represents this same substance after a physical change has taken place?

14. Extra Practice

15. Identify whether the following are physical or chemical changes or properties and explain why
A sheet of copper can be pounded into a bowl
Digesting food
Two cans of paint mixed together
Potassium Burns when placed in water
Acid in tomato sauce can corrode aluminum foil
Barium melts at 725 C
Mixing baking soda and vinegar
Water freezing and forming ice
Gasoline is flammable
An apple will turn brown if left in oxygen

16. Chemical or physical change?
Karla broke her pencil and she can’t put it back together. She thinks it’s a chemical change. Is she correct? Why?

17. Chemical or physical change?
If Ms. Hagan puts food coloring in water, the water color changes so it must be a chemical change right?

18. HOT Question 1
Trey made the following statement when speaking to his lab partners: "Breaking a rock into several pieces is an example of a chemical change. When I started, I had one substance (a rock). At the end, I had several different substances (the different sized pebbles).“ Assess the validity of his claim and justify your reasoning.

19. HOT Question 2
Water (H2O) is made of Hydrogen (a gas) and Oxygen (also a gas). Water is a liquid at room temperature. Based on this, it seems like hydrogen and oxygen combining to form water is a physical change (gases turning into solids). Do you agree with this assessment? Why or why not?

20. HOT Question 4
The diagram below shows particles at the molecular level undergoing a change of some type.
Assess the diagram and explain what type of change you believe to be taking place. Give one example of the type of change this might be. Be sure to justify your answer.

21. HoT Question 5 The image shows the decomposition of Mercury Oxide:
Mercury oxide  Oxygen + Mercury
Mercury oxide is undergoing a chemical change. Prove this using at least three pieces of evidence.