1. Unit: Chemical Quantities
Day 2 - Notes
Unit: Chemical Quantities
Measuring Mass with the Mole

2. After today, you will be able to…
Calculate molar mass of a substance
Use molar mass to calculate the mass of a substance given then number of moles and vice versa

3. Atomic Mass vs. Molar Mass
The atomic mass on the Periodic Table is the mass of a single atom in amu (atomic mass units). Example: 1 carbon atom= amu

4. Atomic Mass vs. Molar Mass
The molar mass (MM) = mass of one mole of a substance. It is equal to the atomic mass in grams. Example: 1 mole of carbon atoms = grams

5. Molar Mass Examples Example: What is the molar mass of Al2S3?
53.96
Round molar masses two decimal places to the right!
+96.21
150.17g Al2S3=1 mol Al2S3

6. Molar Mass Examples Example: What is the molar mass of Ba3(PO4)2?
411.99
61.94
601.93g Ba3(PO4)2=1 mol Ba3(PO4)2

7. Example: What is the mass of 1.33 moles of Ba3(PO4)2?
K: 1.33 mol Ba3(PO4)2
U: ? g Ba3(PO4)2
1.33 mol Ba3(PO4)2
601.93g Ba3(PO4)2 . x = 1
1 mol Ba3(PO4)2
801g Ba3(PO4)2

8. Example: How many moles are equal to 157.8g of CaCl2?
K: g CaCl2
1Ca = 1(40.08) =
2 Cl = 2(35.45) =
40.08
U: ? mol CaCl2
+70.90
110.98
157.8 g CaCl2
1 mol CaCl2 . x = 1
g CaCl2
1.422 mol CaCl2

9. Time to Practice! Complete WS 2
HOMEWORK:
Time to Practice! Complete WS 2