Happy Tuesday! 
12/04/2012
DO NOW!
1. What are the 4 indicators of a chemical
reaction?
2. How is a physical reaction different from a
chemical reaction?
3. Label the following “CC” for chemical
change or “PC” for physical change:
–
–
–
–
–
Burning
Rotting
Rusting
Melting
Combining baking soda and vinegar
ACTIVATOR - Reactions
• Watch the video and write down
any reactions you see.
–Are they chemical or physical
changes do you think?
1. Which is only a
physical change?
souring or milk
melting of ice
burning of oil
rusting of iron
2.Which process involves
a chemical change?
Photosynthesis
freezing water
boiling water
melting ice
HOT Qs
3. In the making an
omelet, which process
involves a chemical
change?
melting butter
frying eggs
chopping onions
stirring eggs
LEQ #8: How are chemical
reactions represented in
writing?
LEQ #9: What can we do to
increase the rate of a reaction?
KEY VOCAB
• CHEMICAL EQUATIONS: how scientists represent
chemical reactions
6 CO2 + 6 H2O  C6H12O6 + 6 O2
This is a really
confusing and stupid
way of doing things
because what normal
person has any idea
what this means?
LUCKILY…
You’re not normal, you’re
chemistry students!
So let’s break it down…
Research
6 CO2 + 6 H2O
Reactants
C6H12O6 + 6 O2
Chemical Reaction
Products
Coefficient
Subscript
KEY VOCAB
• Reactants: substances that take part in a
chemical reaction  What goes in
• Products: substances made during a
chemical reaction  What comes out
+
=
KEY VOCAB
• Coefficient: # of molecules of a compound in a
chemical reaction
– Ex: 6 H = 6 molecules of Hydrogen
• Subscript: # of atoms of an element in a
compound
– Ex: H2O = 2 atoms of Hydrogen in 1 molecule of
water
** REMEMBER – ATOMS MAKE UP
MOLECULES **
PRACTICE
2 H202 2 H20 + O2
1.Reactants?
2.Products?
3.How many molecules of H20 are in the products?
4.How many atoms of Hydrogen are in H202?
5.How many atoms of Hydrogen are in the Reactants?
PRACTICE
C3H8
+
5 O2

4 H2O
+ 3 CO2
1.Reactants?
2.Products?
3.How many molecules of H20 are in the products?
4.How many atoms of Hydrogen are in C3H8?
5.How many atoms of Hydrogen are in the Reactants?
PRACTICE – WORK TOGETHER
4Al + 3 O2  2 Al2O3
1.Reactants?
2.Products?
3.How many molecules of Al203 are in the products?
4.How many atoms of Oxygen are in O2?
5.How many atoms of Oxygen are in the Reactants?
PRACTICE – ON YOUR OWN
1.
2.
3.
4.
5.
6 CO2 + 6 H2O  C6H12O6 + 6 O2
Reactants?
Products?
How many molecules of C02 are in the reactants?
How many atoms of Hydrogen are in H20?
How many atoms of Hydrogen are in the
Reactants?
What in the world is a precipitate?
• http://www.youtube.com/watch?v=8RmVwz2
fNGc (shorter)
• OR
• http://www.youtube.com/watch?v=JAeOP2Mf
rDY&feature=related (longer)
Finding the main idea and supporting
details!
(20 min. 4 min/paragraph)
• Read the article about reaction rates.
• For each paragraph, write down the main idea
and 2 supporting details
• 1 reader and 1 recorder
• Reader reads aloud
• Recorder writes down the main idea and
supporting details
• Switch for each paragraph
Factors that affect the RATE of a
chemical change
• Rate—how quickly
something happens
Factors that affect the RATE of
chemical change
• Temperature
• Surface area
• Concentration