1. The document provides information about a chemistry class, including the objective for the day on converting between grams and moles using molar mass and mole ratios as conversion factors. Practice problems and homework are assigned. 2. Key steps for converting between grams, moles, and atoms using the mole concept and molar mass are reviewed. An example problem demonstrates the three step process. 3. Students complete practice conversion problems in class and are given homework to finish additional practice questions.

1. Launch: 12/10
 Grab your binder and immediately take a seat!
 Place homework (practice questions), binder paper, and
a pen/pencil on your desk.
Today’s Objective: I can convert from grams to
grams using molar mass and mole ratios as
conversion factors
Tonight’s HW: Finish practice problems

2. Launch 12/10
3. Which of the following is a mole ratio for the
equation, 2C3H8 + 7O2  6CO2 + 8H2O
a. 2 mol C3H8
1 mol O2
b. 7 mol O2
5 mol CO2
7 mol O2
c.
2 mol C3H8
7 mol O
d.
8 mol H2O

3. Launch 12/10
__Na + __H2O  __NaOH + __H2
5. When the above equation is completely balanced,
the coefficient for NaOH would be
a. 1.
b. 2.
c. 4.
d. 8.

4. Announcements
 Practice unit exam on Friday
 Worth a quiz grade
 A blank on you grade printout means it is missing!
 Make-up work must be in by Wednesday of next week
 Binder check!
 Unit exam on Thursday of next week (12/17)

5. How many grams? – Part II
Mr. Heffner
12/10/09

6. The “Heart Of Chemistry”
? grams 6.02 X 1023 atoms
1 mole 1 mole
? moles
Grams ? moles Moles Atoms
1 mole 1 mole
? grams 6.02 X 1023 atoms

7. How many grams?
 There is a 3-step process for conversions:
1. Write down the starting information and look at the ending
information.
2. Using the “Heart of Chemistry”, pick the correct conversion
number “How many…”
factor(s).
3. Cancel like terms and do the math!

8. Example #1
2H2 + O2  2H2O
In the equation above, how many grams of O2 are required to
completely react with 4.04 grams of H2?
 Step #1: Write down the starting information and look at the
ending information.
4.04g H2

9. Example #1
2H2 + O2  2H2O
In the equation above, how many grams of O2 are required to
completely react with 4.04 grams of H2?
 Step #2: Pick the correct conversion factor(s).
1 mol H2 1 mol O2 32.00g O2
4.04g H2 X X X =
2.02g H2 2 mol H2 1 mol O2

10. Example #1
2H2 + O2  2H2O
In the equation above, how many grams of O2 are required to
completely react with 4.04 grams of H2?
 Step #3: Cancel like terms and do the math!
1 mol H2 1 mol O2 32.00g O2
4.04g H2 X X X =
2.02g H2 2 mol H2 1 mol O2
4.04 X 1 X 1 X 32.00 g O2
=
2.02 X 2 X 1
4.04 X 32.00 g O2
32.00 g O2 = =
4.04

11. Practice Questions
 Practice questions worksheet

12. How many moles of sodium (Na) are there in 45.98
grams?
1 mol 22.99g
22.99g 1 mol
6.02 X 1023 atoms 1 mol
1 mol 6.02 X 1023 atoms

13. How many grams are there in 2 moles of Br2?
1 mol 159.8g
2.02g 2 mol
6.02 X 1023 atoms 159.8g
1 mol 1 mol

14. How many atoms are there in 2 moles of Br2?
1 mol 1 mol
159.8g 6.02 X 1023 atoms
6.02 X 1023 atoms 159.8g
1 mol 1 mol

15. How many moles are there in 3.01 X 1023 atoms of
C2H8?
1 mol 1 mol
32.1g 6.02 X 1023 atoms
6.02 X 1023 atoms 32.1g
1 mol 1 mol

16. How many grams are there in 1.204 X 1024 atoms
of H2O2?
1 mol 1 mol
34.04g 6.02 X 1023 atoms
6.02 X 1023 atoms 34.04g
1 mol 1 mol

17. How many atoms are there in PCl5?
1 mol 1 mol
208.22g 6.02 X 1023 atoms
6.02 X 1023 atoms 208.22g
1 mol 1 mol

18. How many grams of Na2O would be produced from
11.5 grams of Na?
4Na + O2  2Na2O
1 mol Na 2 mol Na2O
23g Na 4 mol Na
4 mol Na 62g Na2O
2 mole Na2O 1 mol Na2O

19. How many grams of C2H4 are required to
completely react with 16 grams of O2?
C2H4 + 2O2  2CO2 + 3H2O
1 mol C2H4 1 mol C2H4
28.06g C2H4 3 mol O2
1 mol O2 28.06g C2H4
32g O2 1 mol C2H4

20. Exit Slip
1. Which conversion factor(s) would need to be
used to convert 24.02 grams of carbon (C) to
moles?
12.01g 6.02 X 1023 atoms 1 mole
1 mole 1 mole 12.01g
I II III
a. I only
b. II only
c. III only
d. I and II

21. Exit Slip
2. Which conversion factor(s) would need to be
used to convert 3 moles of CH4 to atoms?
16.05g 6.02 X 1023 atoms 1 mole
1 mole 1 mole 16.05g
I II III
a. I only
b. II only
c. III only
d. II and III

22. Exit Slip
3. Which conversion factor(s) would need to be
used to convert 9.03 X 1023 atoms of CH4 to
grams?
16.05g 6.02 X 1023 atoms 1 mole
1 mole 1 mole 6.02 X 1023 atoms
I II III
a. I only
b. II only
c. II and III
d. I and III

23. Exit Slip
4. Which conversion factor(s) would need to be
used to convert of CH4 to grams?
16.05g 6.02 X 1023 atoms 1 mole
I
1 mole II
1 mole III
6.02 X 1023 atoms
a. I only
b. II only
c. II and III
d. I and III

24. Exit Slip
2. Which conversion factor(s) would need to be
used to convert 8.08 grams of H2 to moles?
1 mole
a. 2.02g
1 mole
b. 6.02 X 1023 atoms
6.02 X 1023 atoms
c. 1 mole
d. both a and c

25. Exit Slip
3. Which of the following correctly shows how to convert
64.00g of O2 to atoms?
6.02 X 1023 atoms
a. 32.00g X
32.00g
1 mole
b. 64.00g X 32.00 g
1 mole 6.02 X 1023 atoms
c. 64.00g X 32.00 g X 1 mole
1 mole 1 atoms
d. 64.00 g X X
6.02 X 10 23 g
32.00 moles

26. Exit Slip
4. How many atoms of nitrogen (N) are there in 14.01g?
a. 3.01 X 1023 atoms
b. 6.02 X 1023 atoms
c. 9.03 X 1023 atoms
d. 1.204 X 1024 atoms

27. Exit Slip
5. How many grams does 12.04 X 1023 molecules of
H2O weigh?
a. 9.01g
b. 18.02g
c. 27.03g
d. 36.04g

28. Homework
 Finish practice questions worksheet