Cool Chemistry

1
Cool Chemistry

• Activity 1

2
Properties and Changes

• Physical PROPERTY can observe w/o changing the
  composition of a substance
• ex color, solubility, odor, hardness, density,
  melting pt., boiling pt.
• 2) Physical CHANGE when a substance changes its
  appearance but not its composition cutting,
  tearing, dissolving
• usually reversible
• ex change of state (water changing from
  solid--gt liquid--gt gas), painting wood

3
Homogeneous Substances

• Solution a special kind of mixture 2
  phases/parts (SOLUTE dissolves SOLVENT does the
  dissolving)
• Ex moist air (H2O in Air) sterling silver (Cu
  in Agcalled an alloy)

4
The materials forming a solution are
called______.

• solute and solvent
• molarities
• reactants and products
• solvent

5
Reactants vs. Products

• In a chemical reaction, reactants are chemically
  combined or broken down to make (produce)
  products.

• arrow always points toward products!

CH4(g) 2O2(g) CO2(g) 2H2O(l)
reactants
products
6
An expression in which symbols, formulas, and
numbers are used to represent a chemical reaction
is called a (an)

• symbol
• coefficient
• chemical equation
• atom

7
Properties and Changes

• Chemical PROPERTY the ability to form a new
  substance
• 2) Chemical CHANGE changes the composition of
  the substance
• usually NOT reversible gives off/uses up energy
• ex burning, rotting, rusting, fermenting,
  exploding, corroding

8
Law of Conservation of Mass

• Remember Law of Conservation of Mass in any
  physical or chemical change, matter cannot be
  created or destroyed it may change forms, but it
  is conserved in every case

9
Indication of Chemical Change

• Gas given off
• Light produced
• Precipitate formed
• Exothermic or Endothermic
• Permanent Color Change

10
Which of the following does not indicate that a
chemical change has occurred?

• formation of a precipitate
• melting of a solid
• formation of a gas
• color change

11
Which one of the following statements is true of
a chemical or physical change?

• Dissolving salt in water is a chemical change.
• The solidification of wax is a chemical change.
• The release of heat when magnesium is dropped in
  hydrochloric acid indicates a chemical change.
• A candle burning is a physical change.

12
Polymer

• large molecule formed by the covalent bonding of
  smaller molecules called monomers

13
When two different substances are mixed, a
chemical reaction always occurs.

• True
• False