1. Chemical Calculations
We now have 3 tools to complete chemical Calculations...
Remember...Molar Mass and Avogadro's # are always compared to 1 mol of the substance
1. Molar Mass
2. Avogadro's #
3. Mole Ratio
1 mol X
6.02 x 1023 X Or
(P.T.) g X
1 mol X Or
# mol X
# mol Y Or
(P.T.) g X
1 mol X
1 mol X
6.02 x 1023 X
# mol X
# mol Y

2. Chemical Calulations 4 3 2
_ Fe + _ O _ Fe2O3
How many moles of Fe2O3 are produced when 6.0 moles O2 react?
Follow the 3 Steps...1)what you know 2) what you want to know 3) how do you get there! 2
6.0 mol O2
mol Fe2O3
4.0 =
mol Fe2O3 3
mol O2

3. Learning Check #2 2 3 4
_ Fe + _ O _ Fe2O3
How many moles of Fe are needed to react with 12.0 mol of O2 4
12.0 mol O2
mol Fe
16.0 =
mol Fe 3
mol O2
A) mol Fe
B) mol Fe
C) mol Fe

4. Converting moles of "X" into grams of "Y"
Balance equation
Use coefficients to write a mol-mol factor
Mole Ratio
# mol X
# mol Y
Convert moles of desired to grams
Molar Mass
(P.T.) g Y
1 mol Y

5. Learning Check #3 2 3 4
_ Fe + _ O _ Fe2O3
How many grams of O2 are needed to produce mol of Fe2O3 (Remember…Get to Moles)
mol O2
0.400 mol Fe2O3 3 =
mol O2
.600
mol Fe2O3 2
mol O2
.600
g O2
31.98
g O2 =
19.2
1 mol O2

6. Converting grams of "X" into grams of "Y"
Balance equation
Convert grams of given (X) into moles of X
Molar Mass
(P.T.) g X
1 mol X
Use coefficients to write a mol-mol factor
Mole Ratio
# mol X
# mol Y
Convert moles of desired to grams
Molar Mass
(P.T.) g Y
1 mol Y

7. Chemical Calculation
The reaction between H2 and O2 produces g of water. How many grams of O2 reacted?
Write the equation
_ H2(g) _ O2(g) _ H2O(g)
Balance the equation 2 1 2
_ H2(g) _ O2(g) _ H2O(g)

8. Organize Your Data What you KNOW! What you WANT! How You get there!
Mole Bridge
g H2O
mol H2O
mol O2
g O2
Molar Mass
Mole Ratio
Molar Mass
(P.T.) g H2O
1 mol H2O
2 mol H2O
1 mol O2
(P.T.) g O2
1 mol O2

9. Tool Box Once into moles … go where ever you want = = =
The reaction between H2 and O2 produces 13.1 g of water. How many grams of O2 reacted?
Once into moles … go where ever you want
13.1g H2O
1 mol H2O
18.01 g H2O =
mol H2O
.727
2 mol H2O
1 mol O2
.727 mol H2O =
.364
mol O2
31.98 g O2
1 mol O2
.364 mol O2 =
11.63
g O2
Molar Mass
Mole Ratio
Molar Mass
Tool Box
(P.T.) g O2
1 mol O2
2 mol H2O
1 mol O2
(P.T.) g H2O
1 mol H2O

10. Set up your problem Convert Grams to moles! Cancel the units
With More Practice
Set up your problem
Convert Grams to moles!
Cancel the units
Do the math
13.1g H2O
1 mol H2O
18.01 g H2O
2 mol H2O
1 mol O2
31.98 g O2
1 mol O2 =
11.63
g O2
(P.T.) g H2O
1 mol H2O
2 mol H2O
1 mol O2
(P.T.) g O2
1 mol O2

11. Points to Remember 1. Read an equation in moles
2. Convert given amount to moles
3. Use mole factor to give desired moles
4. Convert moles to grams
grams (given grams (desired)
moles (given) moles (desired)

12. = Learning Check # 4 4 2 Balance the Equation: Complete the set up:
How many O2 molecules will react with 505 grams of Na to form Na2O?
__Na O __Na2O 4 2
Balance the Equation:
Complete the set up:
1 mol O2
4 mol Na
6.02 x 1023 molelcules O2
1 mol O2
505 g Na
1 mol Na
22.99 g Na =
3.30 x 1024 molelcules 16

13. = 2 5 4 2 Learning Check #5 __C2H2 + __O2 __CO2 + __H2O 22.2
Acetylene gas C2H2 burns in the oxyactylene torch for welding. How many grams of C2H2 are burned if the reaction produces 75.0 g of CO2?
__C2H __O __CO2 + __H2O 2 5 4 2 =
75.0 g CO2
1 mol CO2
2 mol C2H2
26.0 g C2H2
22.2
g C2H2
44.0 g CO2
4 mol CO2
1 mol C2H2

14. Pathways for Problems Using Equations
Given (A)
Find (B)
grams (A)
grams (B)
Molar Mass (A)
Molar Mass (B)
moles (A)
moles (B)
Mole Ratio
Coefficients
Avogadro's #
Avogadro's #
particles (A)
particles (B) 20