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

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.

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

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

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

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

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:

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.

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

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