Chemical Change

Chemical Changes

modeled by equations

What do you notice?

• Bonds have been created

• This is a chemical change

• The end is different from the beginning

How is this one different than the last one?

• Bonds were broken

• This is a chemical change

• The end is different than the beginning

Poll

Which equation does not indicates a chemical change?

• 2Fe2O3 → 2Fe2O3

• 2Ag + S → Ag₂S

• C₂H₁₂O₆ → HC₂H₃O₂ + H₂O

• CH4 + 2O2 → CO2 + 2H2O

Multiple Choice

T/F This indicates a chemical change?

2Ag + S → Ag₂S

• True

• False

Multiple Choice

T/F This indicates a chemical change?

C₂H₁₂O₆ → HC₂H₃O₂ + H₂O

• True

• False

Common examples of Chemical changes

Chemical Equations

This is one way we can represent chemical changes

How many of each element is present?

• On each side of the equation

• O = 6

• Fe = 4

Multiple Choice

2H₂O_{2 (l)} ---------> 2H₂O_(g) + O_{2 (g)}

• A liquid has chemically changed into two different gases.

• A gas has chemically changed into a liquid.

• A liquid has chemically changed into a gas.

Multiple Choice

Which is NOT an example of a chemical change?

• Burning newspaper

• Ice melting into liquid water

• The souring of milk

• A nail rusting