1. Balancing Chemical Equations

2. ANNOUNCEMENTS! Research Outline-Rough Draft: due: Feb 5 - 6
Title
Page #
Forming & Naming Notes 53
Forming & Naming IP (4) 54
Book Learning 55
Naming/Writing Chemical Formulas 56
Naming/Writing IP (5) 57
Balancing Equations Notes 58
Balancing Lab 59 60
Balancing IP (3) 61
ANNOUNCEMENTS!
Housekeeping
Rules, Door, Attention signal
Tutoring – 2:15 (NO TUESDAYS)
Sign log
Research Outline-Rough Draft: due: Feb 5 - 6
Class website:
Your classwork is homework if not finished
Work can be checked ANY day/time
Double check your work!
Research Topic Check

3. Law of Conservation of Mass
Law of Conservation of Mass: States that mass is neither created nor destroyed in any ordinary chemical reaction
More simply: the number of atoms for an element on the reactant side must equal the number of atoms on the product side

4. Counting Atoms Subscripts & (Parenthesis)
An uppercase letter next to a lower case letter represents ONE element; example: Na (sodium)
If there is not a number behind the element you can say you have one atom of that element; Example: CO2 you have 1 carbon atom.
When a number is “small” and sits BEHIND an element, we call that a subscript. Example (N2)
When there are parentheses around a compound & and a subscript outside, the subscript multiplies EVERYTHING in the ( ).
Example: (PO3)4
P = 1 x 4 = 4
O = 3 x 4 = 12

5. Counting Atoms Subscripts & (Parenthesis)
2 minutes
Counting Atoms Subscripts & (Parenthesis)
My example: NaCl Na=_____ Cl=____
The next examples you are trying with a partner - 2 minutes
H2O H=_____ O=_____
C8H10N4 C=_____ H=_____ N=_____
Ca(CN)2 Ca=____ C=______ N=_____
(SO4)4 S=______ O=______

6. Counting Atoms Coefficients
Coefficient: A number YOU can place in front of a compound to change how much you have of elements within that compound.
This is just like the coefficients you use in Algebra I & II
Example: 4 NaCl
What is the Coefficient?
How many Na atoms do we have now?
How many Cl atoms do we have now?

7. Counting Atoms Coefficients
Try the following problems on your own: 4 Ag2O Ag=______ O=_______ 25 H2O H=_______ O=_______ 2 Ca3(PO4)2 Ca=______ P=_______ O=_______ 16 CO2 C=______ O=_______

8. Setup of the Basic Chemical Reaction
When a chemical reaction takes place, it ALWAYS follows the following format:
Reactants  Products
What do these words mean?
Reactants = your starting stuff; always located before the arrow
 = yield arrow (means the reaction took place)
Products = the end result; always after the arrow

9. Setup of the Basic Chemical Equation
Notation for a Chemical Equation. A chemical equation consists of the chemical formulas of the reactants (on the left) and the products (on the right). The two are separated by an arrow symbol ("→" usually read aloud as "yields"). Each individual substance's chemical formula is separated from others by a plus sign.
H2 + Br2 → HBr
H2: Diatomic Hydrogen
Br2: Diatomic Bromine
HBr: Hydrogen Bromide
Diatomic hydrogen and diatomic bromine combine to yield hydrogen bromide
Written Formula

10. Practice 5 minutes N2 + H2 → NH3 2. Cu(NO3)2 → CuO + NO2 + O2
3. (NH4)2Cr2O7 → Cr2O3 + N2 + H2O
Cr2o7= dichromate
Cr2o3 = chromium (iii) oxide

11. Independent Practice
Complete the problems on the practice sheet. I will be circulating to answer your questions.
Chapter 4 Section 2 pgs Balancing Chemical Equations CU: #’s 1-2 C2G: #'s 1-12
Work on research IP

12. Balancing Chemical Equations

13. ANNOUNCEMENTS! Research Outline-Rough Draft: due: Feb 5 - 6
Title
Page #
Forming & Naming Notes 53
Forming & Naming IP (4) 54
Book Learning 55
Naming/Writing Chemical Formulas 56
Naming/Writing IP (5) 57
Balancing Equations Notes 58
Balancing Lab 59 60
Balancing IP (3) 61
ANNOUNCEMENTS!
Housekeeping
Rules, Door, Attention signal
Tutoring – 2:15 (NO TUESDAYS)
Sign log
Research Outline-Rough Draft: due: Feb 5 - 6
Class website:
Your classwork is homework if not finished
Work can be checked ANY day/time
Double check your work!
Research Topic Check

14. Balancing Equations
Now we are going to tie all of these pieces together to balance an equation so that we are obeying the Law of Conservation of Mass
Steps/Rules:
Make a chart to count the atoms in your reactants and your products *If an equation is unbalanced, you MAY NOT change the subscript. You are only allowed to change the coefficient out in front.
Count how many atoms you have for each element in EACH compound BEFORE you start placing coefficients out in front.
If you do not put a coefficient in front of a compound, we treat it as a 1.

15. Hg + Br2 Hg2Br2 Hg Br Guided Practice
Nothing else in the equation can be changed other than the coefficient.

16. Guided Practice
FeCl3 + MgO
Fe2O3 + MgCl2 Fe Cl Mg O

17. Li H PO4 Li + H3PO4 H2 + Li3PO4 Guided Practice
The phosphate group (like many of the polyatomic ions) remains together when balancing chemical equations.