1. Launch: 11/16
 Grab your binder and immediately take a seat!
 Place homework (practice questions) on desk.
4Na + 4H2O  4NaOH + 2H2
3. Which of the following identifies the coefficient for
H2O in the above chemical equation?
a. 1
b. 2
c. 4
d. 8

2. Launch 11/16
5. Which of the following identifies the correct
number of atoms in 3H2SO4?
a. 3 H atoms, 3 S atoms, 3 O atoms
b. 2 H atoms, 1 S atom, 4 O atoms
c. 6 H atoms, 3 S atoms, 4 O atoms
d. 6 H atoms, 3 S atom, 12 O atoms

3. Launch: 11/16
 Grab your binder and immediately take a seat!
 Place homework (practice questions) on desk.
HC2H3O2 + NaHCO3  NaC2H3O2 + H2CO3
2. Which of the following correctly identifies all of
the reactants in the above chemical equation.
a. NaC2H3O2
b. NaHCO3
c. NaC2H3O2 and HC2H3O2
d. HC2H3O2 and NaHCO3

4. Launch 11/16
5. Which of the following identifies the correct
number of atoms in 3H2SO4?
a. 3 H atoms, 3 S atoms, 3 O atoms
b. 2 H atoms, 1 S atom, 4 O atoms
c. 6 H atoms, 3 S atoms, 4 O atoms
d. 6 H atoms, 3 S atom, 12 O atoms

5. Launch: 11/16
 Grab your binder and immediately take a seat!
 Place homework (practice questions) on desk.
1. What are chemical equations?
a. Representations of chemical reactions in which the
reactants are listed to the left of a reaction arrow.
b. Representations of chemical bonds in which 2 valence
electrons are depicted by a straight line
c. Representations of chemical reactions in which the.
products are listed to the left of the reaction arrow.
d. A way to show how reaction arrows turn into reactants.

6. Launch 11/16
HC2H3O2 + NaHCO3  NaC2H3O2 + H2CO3
2. Which of the following correctly identifies all of
the reactants in the above chemical equation.
a. NaC2H3O2
b. NaHCO3
c. NaC2H3O2 and HC2H3O2
d. HC2H3O2 and NaHCO3

7. Announcements
 Unit #5: Chemical Reactions & Stoichiometry
 Class points end next week
 Get your HW done
 Be respectful
 Quiz on Friday!

8. Is the equation balanced?
Mr. Heffner
11/16/09

9. What is conservation of matter?
 The Principle of Conservation of Matter states…
 that, in a chemical reaction, atoms cannot be created
or destroyed
2H2 + O2  2H2O
The # of atoms on
the reactants side = The # of atoms on
the products side

10. Is the equation balanced?
 Balanced: the # atoms
is equal on both sides
 Unbalanced: the # of
atoms is not equal on
both sides

11. Example #1
 Is the below equation balanced?
 Count the # of atoms on both sides
2H2 + O2  2H2O
4XH 2XO 4XH
2XO
Multiply the
coefficients and
subscripts
Yes, it is balanced!

12. Whiteboards
 With a partner, determine whether or not the
equations are balanced.
 First, re-write the equation on your whiteboard.
 Then, count the atoms on each sides showing all of
your work!
 Finally, raise your hand to show Mr. Heffner when you
have completed the problem.
 Do not go on to the next problem until you have been
checked off!

13. Practice Questions
 Practice question handouts

14. Exit Slip
1. The “Principle of Conservation of Matter” states
that
a. in a chemical equation, the number of atoms on the
products side must equal then number of atoms on
the reactants side.
b. both of the reactants need to have the same number
of atoms.
c. both of the products need to have the same number
of atoms.
d. in a chemical reaction, matter can be created or
destroyed.

15. Exit Slip
2. Which of the following identifies the correct
number of atoms in 2H3PO4?
a. 2 H atoms, 3 P atoms, 4 O atoms
b. 6 H atoms, 2 P atom, 8 O atoms
c. 6 H atoms, 3 P atoms, 4 O atoms
d. 6 H atoms, 3 P atom, 12 O atoms

16. Exit Slip
Mg + 2H2O  Mg(OH)2 + 2H2
3. Is the above equation balanced?
a. No, because the number of H atoms is not equal
b. No, because the number of O atoms is not equal
c. Yes, because the number of Mg atoms is not equal
d. Yes, because there are equal numbers of atoms on
both sides of the equation

17. Exit Slip
4. Hydrogen gas (H2) and oxygen gas (O2) react to
form water (H2O). Which of these represents a
properly balanced equation for this reaction?
a. H2 + O2  H2O
b. 2H2 + 2O2  2H2O
c. 2H2 + O2  2H2O
d. H2 + 2O2  2H2O

18. Exit Slip
5. Which of the following is a balanced equation for
the combustion of ethanol (C2H6O)?
a. C2H6O + 3O2  CO2 + 2H2O
b. C2H6O + 3O2  2CO2 + 3H2O
c. C2H6O + O2  2CO2 + 3H2O
d. C2H6O + 2O2  3CO2 + 2H2O

19. Homework
 Finish practice question worksheet