1. Chapter 5 Chemical Quantities and Reactions
5.1
The Mole

2. Counting Units Counting units
A counting term states a specific number of items.
1 dozen eggs = 12 eggs
1 case soda = 24 cans
1 ream = 500 sheets of paper

3. Avogadro's Number
Small particles such as atoms, molecules, and ions are
counted using the mole.
1 mole = 6.02 x 1023 items
Avogadro’s number
= 6.02 x 1023

4. Mole of Atoms 1 mole of an element = 6.02 x 1023 atoms of that element
1 mole of carbon = 6.02 x 1023 atoms of carbon
1 mole of sodium = 6.02 x 1023 atoms of sodium

5. Number of Particles in One-Mole Samples

6. Avogadro's Number Avogadro’s number, 6.02 x 1023, can be written as an
equality and as two conversion factors.
Equality:
1 mole = x 1023 particles
Conversion Factors:
6.02 x 1023 particles and mole
1 mole x 1023 particles

7. Guide to Calculating Atoms or Molecules

8. Converting Moles to Particles
Avogadro’s number is used to convert moles of a
substance to particles.
How many CO2 molecules are
in 0.50 mole of CO2?
Step 1 State the needed and given quantities:
Given: mole of CO2
Needed: molecules of CO2

9. Converting Moles to Particles
Step 2 Write a plan to convert moles to atoms or molecules:
Avogadro’s number
moles of CO molecules of CO2
Step 3 Use Avogadro’s number to write conversion factors.
1 mole of CO2 = 6.02 x 1023 molecules of CO2
6.02 x 1023 CO2 molecules and mole CO2
 1 mole CO x 1023 CO2 molecules

10. Converting Moles to Particles
Step 4 Set up the problem to calculate the number of particles.
0.50 mole CO2 x x 1023 molecules CO2
1 mole CO2
= 3.01 x 1023 molecules of CO2

11. Learning Check The number of atoms in 2.0 mole of Al atoms is:
A Al atoms
B x 1023 Al atoms
C x 1024 Al atoms

12. Solution The number of atoms in 2.0 moles of Al atoms is:
Step 1 State the needed and given quantities:
Given: mole Al
Needed: atoms of Al
Step 2 Write a plan to convert moles to atoms or molecules:
Avogadro’s number
Moles of Al Atoms of Al

13. Solution The number of atoms in 2.0 moles of Al atoms is:
Step 3 Use Avogadro’s number to write conversion factors.
1 mole of Al = 6.02 x 1023 atoms of Al
6.02 x 1023 atoms Al and mole A
1 mole Al x 1023 atoms Al

14. Solution The number of atoms in 2.0 moles of Al atoms is:
Step 4 Set up the problem to calculate the number
of particles.
C moles Al x x 1023 Al atoms
1 mole Al
= 1.2 x 1024 Al atoms

15. Learning Check The number of moles of S in 1.8 x 1024 atoms of S is:
A mole of S atoms
B moles of S atoms
C x 1048 moles of S atoms

16. Solution The number of moles of S in 1.8 x 1024 atoms of S is:
Step 1 State the needed and given quantities:
Given: x 1024 atoms of S
Needed: moles of S
Step 2 Write a plan to convert moles to atoms or molecules:
Avogadro’s number
Atoms of S Moles of S

17. Solution The number of moles of S in 1.8 x 1024 atoms of S is:
Step 3 Use Avogadro’s number to write conversion factors.
1 mole S = 6.02 x 1023 atoms of S
6.02 x 1023 atoms S and mole S
1 mole S x 1023 atoms S

18. Solution The number of moles of S in 1.8 x 1024 atoms of S is:
Step 4 Set up the problem to calculate the number of particles.
B. 1.8 x 1024 S atoms x mole S
6.02 x 1023 S atoms
= 3.0 moles of S atoms

19. Moles of Elements in a Formula

20. Moles of Elements in a Formula
The subscripts in a formula show:
the relationship of atoms in the formula
the moles of each element in 1 mole of compound
Aspirin
C9H8O4
1 molecule: 9 atoms of C 8 atoms of H atoms of O
1 mole: moles of C 8 moles of H moles of O

21. Moles of Elements in a Formula
Subscripts are used to write conversion factors for
moles of each element in 1 mole of a compound. For
aspirin, C9H8O4, the possible conversion factors are:
9 moles C moles H moles O
1 mole C9H8O mole C9H8O mole C9H8O4
9 moles C moles H moles O

22. Learning Check
How many atoms of O are in mole of aspirin, C9H8O4?

23. Solution Step 1 State the needed and given quantities:
Given: mole of C9H8O4
Need: molecules of C9H8O4
Step 2 Write a plan to convert moles to atoms or molecules:
Moles of aspirin Moles of O Atoms of O

24. Solution Step 3 Use Avogadro’s number to write conversion factors.
Subscript factor: 1 mole of C9H8O4 = 4 moles of O
1 mole C9H8O and moles O
4 moles O mole C9H8O4
Avogadro’s number:
1 mole of O = 6.02 x 1023 atoms of O
1 mole O and x 1023 atoms O
6.02 x 1023 atoms O mole O

25. Solution
Step 4 Set up the problem to calculate the number of particles.
0.150 mole C9H8O4 x 4 mole O x x 1023 atoms O
1 mole C9H8O mole O
= x 1023 atoms of O

26. Chapter 5 Chemical Quantities and Reactions
5.2
Molar Mass

27. Molar Mass The molar mass is the mass of 1 mole of an element
is the atomic mass expressed in grams

28. Molar Mass from Periodic Table
Molar mass is the atomic mass expressed in grams.
1 mole of Ag mole of C mole of S
= g of Ag = 12.0 g of C = 32.1 g of S

29. Learning Check
Give the molar mass for each element (to the tenths place).
A. 1 mole of K atoms = ________
B. 1 mole of Sn atoms = ________
C. 1 mole of Ca atoms = ________

30. Solution Give the molar mass for each element (to the tenths place).
A. 1 mole of K atoms = g of K
B. 1 mole of Sn atoms = g of Sn
C. 1 mole of Ca atoms = g of Ca

31. Guide to Calculating Molar Mass

32. Molar Mass of the Compound C2H6O
To calculate the molar mass of C2H6O:
Step 1 Obtain the molar mass of each element.
1 mole of C = g of C
1 mole of H = g of H
1 mole of O = g of O

33. Molar Mass of the Compound C2H6O
Step 2 Multiply each molar mass by the number of moles (subscripts) in the formula.
2 moles C x g C = g of C
1 mole C
6 moles H x g H = g of H
1 mole H
1 mole O x g O = g of O
1 mole O

34. Molar Mass of the Compound C2H6O
Step 3 Calculate the molar mass by adding the masses of the elements.
2 moles of C = g of C
6 moles of H = g of H
1 mole of O = g of O
Molar mass of C2H6O = g of C2H6O

35. One-Mole Quantities

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

37. Solution What is the molar mass of each compound?
Step 1 Obtain the molar mass of each element.
A. K2O K = 39.1 g/mole
O = 16.0 g/mole
B. Al(OH)3 Al = 27.0 g/mole
O = 16.0 g/mole
H = 1.01 g/mole

38. Solution What is the molar mass of each compound?
Step 2 Multiply each molar mass by the number of moles
(subscripts) in the formula.
A. K2O
2 moles K x g K = g of K
1 mole K
1 mole O x g O = g of O
1 mole O

39. Solution What is the molar mass of each compound?
Step 2 Multiply each molar mass by the number of moles
(subscripts) in the formula.
B. Al(OH)3
1 mole Al x g Al = 27.0 g of Al
1 mole Al
3 moles O x g O = 48.0 g of O
1 mole O
3 moles H x g H = g of H
1 mole H

40. Solution What is the molar mass of each compound?
Step 3 Calculate the molar mass by adding the masses of the elements.
A. K2O 2 moles of K = g of C
1 mole of O = g of O
Molar mass of K2O = g of K2O
B. Al(OH)3 1 mole of Al = g of Al
3 moles of O = g of O
3 moles of H = g of H Molar mass of Al(OH)3 = g of Al(OH)3

41. Learning Check
Prozac, C17H18F3NO, is an antidepressant that inhibits the
uptake of serotonin by the brain. What is the molar mass
of Prozac?
A g/mole
B g/mole
C g/mole

42. Solution Step 1 Obtain the molar mass of each element.
1 mole of C = g of C
1 mole of H = g of H
1 mole of F = g of F
1 mole of N = g of N
1 mole of O = g of O

43. Solution
Step 2 Multiply each molar mass by the number of moles (subscripts) in the formula.
17 moles C x g = g of C
1 mole C
18 moles H x g = g of H
1 mole H
3 moles F x g = g of F
1 mole F
1 mole N x g = g of N
1 mole N
1 mole O x g = g of O
1 mole O

44. Solution
Step 3 Calculate the molar mass by adding the masses of the elements:
1 mole of C17H18F3NO = 309 g of C17H18F3NO

45. Calculations Using Molar Mass
Molar mass conversion factors
are fractions (ratios) written from the molar mass.
relate grams and moles of an element or compound.
for methane, CH4, used in gas stoves and gas heaters, is
1 mole of CH4 = 16.0 g of CH4 (molar mass equality)
Conversion factors:
16.0 g CH and mole CH4
1 mole CH g CH4

46. Guide to Calculating Moles from Mass

47. Converting Mass to Moles of Compound NaCl
A box of table salt, NaCl, contains 737 g of NaCl.
How many moles of NaCl are in the box?

48. Converting Mass to Moles of Compound NaCl
A box of table salt, NaCl, contains 737 g of NaCl.
How many moles of NaCl are in the box?
Step 1 State the given and needed quantities.
Given: g of NaCl
Need: moles of NaCl
Step 2 Write a plan to convert grams to moles.
molar mass
Grams of NaCl Moles of NaCl

49. Converting Mass to Moles of Compound NaCl
Step 3 Determine the molar mass and write conversion factors.
Molar Mass
1 mole Na x g Na = 23.0 g of Na
1 mole Na
1 mole Cl x g Cl = 35.5 g of Cl
1 mole Cl g of NaCl
Conversion Factors
1 mole of NaCl = g of NaCl
58.5 g NaCl and 1 mole NaCl
1 mole NaCl g NaCl

50. Converting Mass to Moles of Compound NaCl
Step 4 Set up the problem to convert grams to moles.
737 g NaCl x 1 mole NaCl = moles of NaCl
58.5 g NaCl

51. Map: Mass – Moles – Particles

52. Learning Check Allyl sulfide, C6H10S, is a compound that has
the odor of garlic. How many moles of
C6H10S are in 225 g?

53. Solution Step 1 State the given and needed quantities.
Given: g of C6H10S
Need: moles of C6H10S
Step 2 Write a plan to convert grams to moles.
molar mass
Grams of C6H10S Moles of C6H10S

54. Solution Step 3 Determine the molar mass and write conversion factors.
6 moles C x g C = g of C
1 mole C
10 moles H x g H = g of H
1 mole H
1 mole S x g S = g of S
1 mole S
= g of C6H10S

55. Solution Step 3 Determine the molar mass and write conversion factors.
1 mole of C6H10S = g of C6H10S
114.2 g C6H10S and 1 mole C6H10S
1 mole C6H10S g C6H10S
Step 4 Set up the problem to convert grams to moles.
225 g C6H10S x 1 mole C6H10S
114.2 g C6H10S
= 19.7 moles of C6H10S