1. DO NOW
Pick up 2 handouts. One is notes and the other is the homework handout.
Yesterday’s lab is due Monday.

2. Density Block lab
Check the Density Block lab for correct number of sig figs, units everywhere and that you have written the formulas and shown all work.
Turn it in.

3. PHYSICAL CHANGES
Changes in matter that DO NOT change the identity of the substance.
Tearing Crushing Cutting Dissolving
Phase changes (melting, freezing, etc.)

4. TRY THESE – ARE THESE PHYSICAL CHANGES?
crushing a can  
melting an ice cube  
burning paper  
boiling water  
mixing sand and water  
breaking a glass  
dissolving sugar and water  
Rusting iron 
mixing red and green marbles  
sublimating dry ice

5. CHEMICAL CHANGES
Changes in matter that DO change the identity of the substance.
Rusting burning fermenting metabolism
ANY chemical reaction

6. TRY THESE – ARE THESE PHYSICAL OR CHEMICAL CHANGES?
burning wood
casting silver in a mold
mixing acid and base
digesting food
crumpling a sheet of paper
melting an ice cube
dissolving salt in water
breaking a bottle

7. EVIDENCE OF CHEMICAL CHANGE
To distinguish between chemical and physical changes, you need to determine if the substance has been changed into something else.
Look at the substance’s physical properties and see if they have changed.
There are some clues – list them:

8. massreactants should ALWAYS equal the massproducts.
CONSERVATION OF MASS
Matter cannot be created or destroyed.
It can be converted into energy (not by you and I), but through nuclear reactions.
As a result:
massreactants should ALWAYS equal the massproducts.

9. EXAMPLE
52.0g of sodium reacts with 160.4g chlorine gas to form sodium chloride. How many grams of sodium chloride are formed?

10. HOMEWORK Physical and Chemical Changes handout due tomorrow.
Physical and Chemical Properties lab due Monday.