1. Chapter 7 Chemical Quantities
7.3
Molar Mass

2. Molar Mass The molar mass
Is the mass of one mole of an element or compound
Is the atomic mass expressed in grams
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3. Molar Mass from Periodic Table
Is the atomic mass expressed in grams

4. Learning Check Give the molar mass for: A. 1 mol K atoms = ________
B. 1 mol Sn atoms = ________

5. Solution Give the molar mass for: A. 1 mol K atoms = 39.10 g
B. 1 mol Sn atoms = g

6. Molar Mass of a Compound
The molar mass of a compound is the sum of the molar masses of the elements in the formula.
Example: Calculate the molar mass of CaCl2.
Element
Number of Moles
Atomic Mass
Total Mass Ca 1
40.08 g/mol
40.08 g Cl 2
35.45 g/mol
70.90 g
CaCl2 g

7. Molar Mass of K3PO4 Calculate the molar mass of K3PO4. Element
Number of Moles
Atomic Mass
Total Mass in K3PO4 K 3
39.10 g/mol
117.3 g P 1
30.97 g/mol
30.97 g O 4
16.00 g/mol
64.00 g
K3PO4
212.3 g

8. Some One-Mole Quantities
32.07 g g g g g

9. Learning Check What is the molar mass of each of the following? A. K2O
B. Al(OH)3

10. Solution
A. K2O g/mol
2 mol K (39.10 g/mol) + 1 mol O (16.00 g/mol)
78.20 g g = g
B. Al(OH) g/mol
1 mol Al (26.98 g/mol) + 3 mol O (16.00 g/mol)
+ 3 mol H (1.008 g/mol)
26.98 g g g = g

11. Learning Check
Prozac, C17H18F3NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac?
1) g/mol
2) g/mol
3) g/mol

12. Solution
Prozac, C17H18F3NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac?
3) g/mol
17C (12.01) + 18H (1.008) + 3F (19.00)
+ 1N (14.01) + 1 O (16.00) =
= g/mol