1. Which of the following is an example of a physical change?A. dissolving salt into waterB. hard-boiling an eggC. burning wood into charcoalD. rusting iron

2. Which of the following is an example of a chemical change?A. ice meltingB. pounding gold into a coinC. paint fadingD. a puddle of water evaporating

3. A chemical change occurs whenever .A. substances are mixedB. objects change shapeC. hot objects meltD. new substances form

4. A chemical change can only be reversed by change.A. a chemicalB. a physicalC. both a physical and a chemical D. a phase

ReviewReview

• Mixtures

• Heterogeneous

• Homogeneous

• Separation of mixtures

Chemical ReactionsChemical Reactions◙Chemical equations represent

chemical reactions

◙Shows two things:

◙What you start with

◙What you end up with

Chemical ReactionsChemical Reactions Reactants- substance(s)

you start with Left side of arrow () Products- substance(s) you

end up with Right side of arrow ()

Chemical ReactionsChemical Reactions▓Fe + S FeS

▓The properties of iron sulfide are different from iron and sulfur

Reactants Product

Signs of a Chemical ReactionSigns of a Chemical Reaction

Products have different properties than the reactants

Color change Gas formation Solid precipitate forms Transfer or release of energy

Conservation of MatterConservation of Matter In a chemical reaction,

atoms rearrange New products form Is matter destroyed? No!!!!!!!

Conservation of MatterConservation of Matter☻Find the mass

of the reactants

☻Reactants- all the substances that take part in the reaction

Light Stick

Plastic tube

Liquid 1

Glass tube

Liquid 2

Conservation of MatterConservation of Matter☺Find the mass

of the products

☺Products- all the substances formed, new and/or existing

Light Stick

Plastic tube

Broken glass

New liquid

Conservation of MatterConservation of Matter

In any chemical reaction, no mass is gained or lost

Mass of the reactants = the mass of all the products, seen or unseen