1. Molar Mass Conversions
1 mol of Fe atoms is
55.85 g/mol
How many grams in 2.00 mol Fe?
or 3.00 mol Fe?
or mol Fe?

2. Use molar mass to convert between mass and moles.
(get MM from the PT)
Type 3
mol grams
2.50 mol x g = ______ g
1 mol
Type 4
grams mol
24.02 g x 1 mol = _____ mol
12.01 g

3. What is the mass of 9.45 mol Al2O3 ?
Type 3
mol grams
Aluminum satellite dishes resist corrosion because the Al reacts with O2 to form a coating of aluminum oxide (Al2O3).
What is the mass of 9.45 mol Al2O3 ?
9.45 mol x
101.96
______g =
1 mol
964 g
Al2O3
2 (26.98) + 3 (16.00) =
g/mol

4. Find the mass, in grams, of 0.0452 mol C20H42 (wax).
Type 3
mol grams
Find the mass, in grams, of mol C20H42 (wax).
mol x
282.62
______g =
1 mol
12.8 g
C20H42
20 (12.01) + 42 (1.01) =
g/mol

5. Type 4 grams mol Fe2O3 159.70 g/mol
When iron is exposed to air, it corrodes to form red-brown rust which is iron(III) oxide (Fe2O3).
How many moles are in 92.2 g of Fe2O3 ?
92.2 g x
______= g
1 mol
0.577 mol
Rust weakens an iron chain.
Fe2O3
2 (55.85) + 3 (16.00) =
g/mol

6. N2O Find the number of moles in 258 g dinitrogen monoxide. Type 4
grams mol
Find the number of moles in 258 g dinitrogen monoxide.
N2O
258 g x
______=
44.02 g
1 mol
5.86 mol
N2O
2 (14.01) + 1 (16.00) =
44.02 g/mol

7. 1. Where do you look to get the molar mass of an element?
Quick Quiz!
1. Where do you look to get the molar mass of an element?
Avogadro’s number
the periodic table
your neighbor’s paper
your face

8. Quick Quiz.
2. Calculate the mass in grams of a sample containing 1.85 mol of water.
1.11 x 1024 g
33.3 g
18.02 g
8460 g
MM = g/mol

9. Quick Quiz.
3. Calculate the number of moles in a spoonful of table salt (NaCl) having a mass of 3.50 g.
208 mol
2.58  103 mol
mol
17.0 mol
MM = g/mol