1. Chapter 3

2. Collection Terms 1 trio = 3 singers
1 six-pack Cola = 6 cans Cola drink
1 dozen donuts = 12 donuts
1 gross of pencils = 144 pencils

3. A Moles of Particles Contains 6.02 x 1023 particles
1 mole C = x 1023 C atoms
1 mole H2O = x 1023 H2O molecules
1 mole NaCl = x 1023 Na+ ions and
6.02 x 1023 Cl– ions

4. Examples of Moles Moles of elements 1 mole Mg = 6.02 x 1023 Mg atoms
1 mole Au = x 1023 Au atoms
Moles of compounds
1 mole NH3 = x 1023 NH3 molecules
1 mole C9H8O4 = x 1023 aspirin molecules

5. Avogadro’s Number
6.02 x 1023 particles
1 mole or
1 mole

6. The Mole and Molar
The mole is defined as the amount of a substance that contains as many elementary entities as there are atoms in exactly 12 g of carbon-12.
The experimentally determined number is called Avogadro’s number (NA)
NA = x 1023

7. NA = 6.0221415 x 1023 The Mole and Molar Mass
One mole each of some familiar substances:
sulfur (left)
copper (middle)
mercury (right)
helium (in balloon)
NA = x 1023

8. Learning Check
Suppose we invented a new collection unit called a mep. One mep contains 8 objects.
A. How many paper clips in 1 mep?
1) ) ) 8
B. How many oranges in 2.0 meps?
1) ) ) 16
C. How many meps contain 40 gummy bears?
1) ) ) 20

9. Solution
Suppose we invented a new collection unit called a mep. One mep contains 8 objects.
A. How many paper clips in 1 mep?
3) 8
B. How many oranges in 2.0 meps?
3) 16
C. How many meps contain 40 gummy bears?
1) 5

10. Learning Check 1. Number of atoms in 0.500 mole of Al 1) 500 Al atoms
2) x 1023 Al atoms
3) x 1023 Al atoms
2.Number of moles of S in 1.8 x 1024 S atoms
1) mole S atoms
2) mole S atoms
3) x 1048 mole S atoms

11. Solution 1. Number of atoms in 0.500 mol of Al 3) 3.01 x 1023 Al atoms
0.500 mol Al x x 1023 Al atoms
1 mol Al
2. Number of moles of S if a sample of S contains 1.80 x 1024 S atoms
2) mole S atoms
1.80 x 1024 S atoms x mol S
6.02 x 1023 S atoms

12. Molar Mass Number of grams in 1 mole
Equal to the numerical value of the atomic mass
1 mole of C atoms = g
1 mole of Mg atoms = 24.3 g
1 mole of Cu atoms = 63.5 g

13. Learning Check Give the molar mass to 0.1 g
A. 1 mole of Br atoms = ________
B. 1 mole of Sn atoms = ________

14. Solution Give the molar mass to 0.1 g
A. 1 mole of Br atoms = 79.9 g/mole
B. 1 mole of Sn atoms = g/mole

15. Molar Mass of Compounds
Mass in grams of 1 mole equal numerically to the sum of the atomic masses
1 mole of CaCl2 = g/mole
1 mole Ca x 40.1 g/mole
+ 2 moles Cl x 35.5 g/mole
1 mole of N2O4 = 92.0 g/mole
2 moles N x 14.0 g/mole
+ 4 moles O x 16.0 g/mole

16. Learning Check A. 1 mole of K2O = ______g
B. 1 mole of antacid Al(OH)3 = ______g

17. Solution
A. 1 mole of K2O = g
2 K x 39.1 g/mole + 1 O x 16.0 g/mole
B. 1 mole of antacid Al(OH)3 = g
1 Al x 27.0 g/mole + 3 O x 16.0 g/mole
+ 3 x 1.0

18. Learning Check
Prozac, C17H18F3NO, is a widely used antidepressant that inhibits the uptake of serotonin by the brain. It has a molar mass of
1) g/mole
2) 262 g/mole
3) 309 g/mole

19. Solution
Prozac, C17H18F3NO, is a widely used antidepressant that inhibits the uptake of serotonin by the brain. It has a molar mass of
3) 309 g/mole
17C (12.0) + 18H (1.0) + 3F (19.0) + 1N (14.0) + 1 O (16.0)

20. Learning Check
What is the percent carbon in C5H8NO4 (MSG monosodium glutamate), a compound used to flavor foods and tenderize meats?
1) %C
2) %C
3) %C

21. Solution Molar mass = 146.0 g/mole % = total g C x 100
total g compound
= g C x 100 = 41.1% C
146.0 g MSG

22. Molar Mass Factors
Methane CH4 known as natural gas is used in gas cook tops and gas heaters. Express the molar mass of methane in the form of conversion factors.
Molar mass of CH4 = g
16.0 g CH and mole CH4
1 mole CH g CH4

23. Learning Check
Acetic acid CH3COOH is the acid in vinegar . It has a molar mass of 60.0 g/mole.
1 mole of acetic acid = ____________
1 mole acetic acid or g acetic acid
g acetic acid mole acetic acid

24. Solution
Acetic acid CH3COOH is the acid in vinegar . It has a molar mass of 60.0 g/mole.
1 mole of acetic acid = g acetic acid
1 mole acetic acid or g acetic acid
60.0 g acetic acid 1 mole acetic acid

25. Calculations with Molar Mass
Grams Moles

26. Moles and Grams 3.00 moles Al ? g Al
Aluminum is often used for the structure of light-weight bicycle frames. How many grams of Al are in 3.00 moles of Al?
3.00 moles Al ? g Al

27. 1. Molar mass of Al 1 mole Al = 27.0 g Al
2. Conversion factors for Al
27.0g Al or mol Al
1 mol Al g Al
3. Setup 3.00 moles Al x g Al
1 mole Al
Answer = g Al

28. Learning Check
The artificial sweetener aspartame (Nutri-Sweet) formula C14H18N2O5 is used to sweeten diet foods, coffee and soft drinks. How many moles of aspartame are present in 225 g of aspartame?

29. Solution 1. Molar mass of Aspartame C14H18N2O5
(14 x 12.0) + (18 x 1.01) + (2 x 14.0) + (5 x 16.0) = 294 g/mole
2. Setup
225 g aspartame x 1 mole aspartame
294 g aspartame
= mole aspartame