1. Determine the Gram Formula Mass
of a compound
2. Convert between Grams and Moles
3. Convert between Moles and Grams
Every element has a different atomic mass
12.011g/mole
12.011g = 1 mole
Molar Mass = 207.2 g/mol
1 mole of Lead = 207.2 g
Atomic Mass
has a unit of
grams/mole
Mass of Magnesium = 24.305 g/mol
1 mole of Magnesium is 24.305 grams
Mass of Mg
24.305 g/mol
Solve the following problem:
How many moles are present in 55 g
of Magnesium?
Convert 55g of Mg to Moles
55 g Mg
1 mol Mg
24.305 g Mg
= 2.26 moles Mg
If 1 mole is 24 g, I predict 55 g is more than 1
mole
1. Cu(NO3)2
#1 How many of each
atom are present
Cu = 1 X 63.546 g/mol
#2
What are the
masses of each atom?
N=2
O=6
#3
Multiply the #
of atoms by the mass
+
X
X
14.007 g/mol
15.999 g/mol
187.554 g/mol
1 mole of Cu(NO3)2 is 187.554 g
#4
Add up the
amounts and this is the
Gram Formula Mass
2. KMnO4
#1 How many of each
atom are present
K=1
#2
What are the
masses of each atom?
X
39.098 g/mol
Mn = 1 X 54.938 g/mol
O = 4 X 15.999 g/mol
#3
Multiply the #
of atoms by the mass
158.032 g/mol
#4
Add up the
amounts and this is the
Gram Formula Mass
+
1 mole of KMnO4 is 158.032 g
Do the rest as
Homework!
Now, take out
“Moles and Mass”
Convert 25g of NaCl to Moles
1. NaCl = Sodium Chloride
Na = 1 x 22.990 g/mol
+ Cl = 1 x 35.453 g/mol
#1 Name the Compound
#2 Find the GFM
58.443 g/mol Conversion Factor!
#3 Convert grams to
moles (Use dimensional
analysis)
25 g NaCl 1 mol NaCl
58.443 g NaCl
= 0.43 moles NaCl
If 1 mole is 58 g, I predict 25 g is less than 1 mole
Convert 405 g of Ag2SO4 to Moles
2.Ag2SO4
= Silver (I) Sulfate
#1 Name the Compound
Ag = 2 x 107.87 g/mol
#2 Find the GFM
S = 1 x 32.06 g/mol
#3 Convert grams to
moles (Use dimensional
analysis)
+ O = 4 x 15.999 g/mol
311.796 g/mol
405 g Ag2SO4
Conversion Factor!
1 mol Ag2SO4
= 1.30 moles Ag2SO4
311.796 g Ag2SO4
If 1 mole is 311 g, I predict 405g is more than 1 mole
Do Not Forget Units
Predictions Help
Section 2 (on back): Converting
from Moles to Grams
Simply flip the conversion factor around!
Convert 0.250 moles of NaCl to grams
1. NaCl = Sodium Chloride
Na = 1 x 22.990 g/mol
+ Cl = 1 x 35.453 g/mol
58.443 g/mol Conversion Factor!
0.250 mol NaCl 58.443 g NaCl
1 mol NaCl
#1 Name the Compound
#2 Find the GFM
#3 Convert moles to
grams(Use dimensional
analysis)
Notice moles on bottom!
= 14.6 grams NaCl
If 1 mole is 58 g, and I have 0.250 moles, the
answer should be less than 58 g of NaCl
Convert 1.70 moles of SiO2 to grams
2. SiO2 = Silicon Dioxide
Si = 1 x 28.086 g/mol
+ O = 2 x 15.999 g/mol
60.084 g/mol Conversion Factor!
1.70 mol SiO2
60.084 g SiO2
1 mol SiO2
#1 Name the Compound
#2 Find the GFM
#3 Convert moles to
grams(Use dimensional
analysis)
moles on
=Notice
102.1428
g bottom!
SiO2
If 1 mole is 60 g, and I have 1.70 moles, the
answer should be more than60 g of SiO2
1. Determine the GFM of a compound
2. Convert between Grams and Moles
3. Convert between Moles and Grams
Try the rest as Homework
Gram Formula Mass
# 3,4,5,6,7
3. Fe2SO4
#1 How many of each
atom are present
Fe = 2 X 55.847 g/mol
#2
What are the
masses of each atom?
S=1
O=4
#3
Multiply the #
of atoms by the mass
+
X
X
32.066 g/mol
15.999 g/mol
207.7576 g/mol
1 mole of Fe2SO4 is 207.7576 g
#4
Add up the
amounts and this is the
Gram Formula Mass
C6H12O6
C = 6 x 12.011g/mol
H = 12 x 1.0079g/mol
+
O = 6 x 15.999g/mol
180.1548 g/mol
This bag is 1 mole or 6.02 x 1023 molecules
of Sucrose
Mass to Moles
Side #1 = 3,4,5
Convert 105.5 g of P2O5 to Moles
3. P2O5
= Phosphorus Pentoxide
P= 2 x 30.974 g/mol
O = 5 x 15.999 g/mol
+
141.945g/mol
Conversion Factor!
100.5 g P2O5
1 mol P2O5
#1 Name the Compound
#2 Find the GFM
#3 Convert grams to
moles (Use dimensional
analysis)
= .70 moles P2O5
141.945 g P2O5
If 1 mole is 142 g, I predict 100.5g is less than 1 mole
Convert 538.2 g of (NH4)2CrO4 to Moles
4. (NH4)2CrO4= Ammonium Chromate #1 Name the Compound
N = 2 x 14.0067 g/mol
H = 8 x 1.0079 g/mol
S = 1 x 32.066 g/mol
+ O = 4 x 15.999 g/mol
132.14 g/mol
538.2 g (NH4)2CrO4
Conversion Factor!
1 mol (NH4)2CrO4
132.14 g (NH4)2CrO4
#2 Find the GFM
#3 Convert grams to
moles (Use dimensional
analysis)
= 4.07 moles (NH4)2CrO4
If 1 mole is 132 g, I predict 538.2g is more than 1 mole
Convert 75 g of TiO4 to Moles
5. TiPO4
= Titanium Phosphate
#1 Name the Compound
Ti= 1 x 47.88 g/mol
#2 Find the GFM
O = 4 x 15.999 g/mol
#3 Convert grams to
moles (Use dimensional
analysis)
+
111.878 g/mol
Conversion Factor!
75 g TiO4
1 mol TiO4
= .67 moles TiO4
111.878 g TiO4
If 1 mole is 112 g, I predict 75g is less than 1 mole
Moles to Grams
Side #2 = 3,4,5
Convert .0078 moles of CrPO4 to grams
3. CrPO4 = Chromium Phosphate
Cr = 1 x 51.9961 g/mol
#1 Name the Compound
#2 Find the GFM
P = 1 x 30.9738 g/mol
+ O = 4 x 15.999 g/mol
146.968g/mol
.0078 mol CrPO4
Conversion Factor!
146.968 g CrPO4
1 mol CrPO4
#3 Convert moles to
grams(Use dimensional
analysis)
moles on
=Notice
102.1428
g bottom!
SiO2
If 1 mole is 145 g, and I have.0078 moles, the
answer should be less than 145 g of CrPO4
Convert .31 moles of N2O to grams
4. N O = Dinitrogen Monoxide
#1 Name the Compound
2
N = 2 x 14.00674g/mol
+ O = 1 x 15.999 g/mol
44.0129 g/mol
.31 mol N2O
Conversion Factor!
44.0129g N2O
1 mol SiO2
#2 Find the GFM
#3 Convert moles to
grams(Use dimensional
analysis)
moles on
=Notice
102.1428
g bottom!
SiO2
If 1 mole is 44 g, and I have .31 moles, the answer
should be less than 44 g of N2O
Convert 83.1 moles of I2 to grams
5. I2 = Iodine Gas
+
I = 2 x 126.904
253.808 g/mol
83.1 mol I2
Conversion Factor!
253.808 g I2
1 mol I2
#1 Name the Compound
#2 Find the GFM
#3 Convert moles to
grams(Use dimensional
analysis)
moles on
=Notice
102.1428
g bottom!
SiO2
If 1 mole is 254 g, and I have 83.1 moles, the
answer should be more than 254 g of I2