1. Introduction to the mole and molar mass Get you calculator
Introduction to the mole and molar mass Get you calculator. You’re going to need it!
Mr.H Revised

2. L.O: Have a conceptual understanding of the mole
as the method of “counting” items and finding the mass of item.
Be able to calculate the number of moles if given the number of items.
Be able to calculate the mass of a sample if given the number of moles in a sample.
Be able to determine the molar mass of a compound.

3. Background
When you buy eggs you usually ask for a _______ eggs.
You know that one dozen of any item is ______.
Dozen 12

4. Paper Paper is packaged by a ream. A ream of paper has 500 sheets.
Why is it useful to use units like a dozen or a ream?
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5. What determines how many items should make up a particular unit?

6. If you were asked to design a new unit to count something, what would you consider when choosing how many items should be included in your new counting unit?

7. Materials
3 packages of different types of candy, balance, worksheet, calculator, pencil.

8. Part 1 Record the number of items in each package.
Measure the mass of each package. Record the mass of each package in the data table.
Answer questions in Analysis and Interpretations.
Record masses your group measured on the board summarizing class data.

9. Number of items in package
Data Table 1
Name of the Items in the Package
Number of items in package
Mass of the package
Jolly Ranchers
Caramels
Hershey's Kisses
26.9 4
23.03 4
20.96 4

10. ANALYSIS AND INTERPRETATION
As you know, a dozen represents 12 items.
Since I did not have enough items to make a dozen, I decided to make a new counting unit. I called this unit a MANU. Each of your packages contains
_____ items. 4

11. 1. A MANU of oranges will have _____ oranges.4
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12. 2. A MANU of pretzels has ____ pretzels.4
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13. 3. A MANU of molecules of water has ____ molecules of water.4
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14. 4. A MANU of particles has ___ particles.
4. A MANU of particles has ___ particles. 4

15. 5. A MANU of atoms of iron has _____ atoms of iron.4 26 Fe
55.85
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16. 6. A MANU of formula units of salt has _______ formula units of salt.4
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17. 7. How many Hershey’s Kisses are in 2 MANUS? _______8
Image Source: SStevens 2005

18. 8. How many caramels are in 10 MANUS? _______40
Image source: SStevens 2005

19. 9. How many Dum Dum Pops are in 400 MANUS? _______
1600
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20. 10. How many Starbursts are in 1/2 MANU? _____
Image source: SStevens 2005

21. 11. Write the formula for finding the number of items (x), if given the number of MANUS (n)
X = 4n

22. 12. How many oranges are in 5 MANUS? _______20
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23. 13. How many apples are in 0.5 MANUS? _______2
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24. 14. How many pencils are in 0.25 (1/4) MANUS? ___
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25. 15. How many atoms of silver are in 20 MANUS? _______80 47 Ag
107.9
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26. 16. How many molecules of water are in 5 MANUS? _______20
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27. 17. How many MANUS are 16 Hershey’s Kisses? ______4
Image Source: SStevens 2005

28. 18. How many MANUS are 100 pretzels? ____25
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29. 19. How many MANUS are 400 lulu icecreams? ____
100
Image Source: SStevens 2005

30. 20. How many MANUS is 1 orange? ________
(Write a fraction or a decimal.)
¼ 0.25
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31. 21. How many MANUS are 2 caramels? _____
0.5
Image Source: SStevens 2005

32. 22. Write your own formula for finding the number of MANUS (x) given the number of pieces (n)
X = n/4

33. 23. How many MANUS are 48 Hershey’s Kisses? ____12
Image Source: SStevens 2005

34. 24. How many MANUS are 32 Hershey’s Kisses? ______8
Image Source: SStevens 2005

35. 25. How many MANUS are 24 Jolly Ranchers? ______6
Image Source: SStevens 2005

36. 26. How many MANUS are 2 Gobstoppers? ______.5
Image Source: SStevens 2005

37. 27. How many MANUS are 20 caramels? ______5
Image Source:Sstevens 2005

38. MANUS MANU of molecules of water would be too small to see.
Scientists had to select a bigger unit for counting molecules of substances.
The unit scientists use is called a MOLE.

39. One MOLE of anything has 602,200,000,000,000,000,000,000 items.
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40. 6.022 x 1023 One MOLE of anything has 6.022 x 1023 items.
AVOGADRO’S NUMBER
6.022 x 1023
One MOLE of anything has x 1023 items.

42. 28. How many Hershey’s Kisses make up 1 MOLE?
6.022 x 1023
Image Source: SStevens 2005

43. 29. How many caramels make up 10 MOLES?
10 x [6.022 x 1023]
60.22 x 1023 Or
6.022 x 1024
Both correct!

44. 30. Find the number of Jolly Ranchers in 4 MOLES.
4 [6.022 x 1023] x x 1024

45. 31. Find the number of atoms of sodium in 2 MOLES.
2[6.022 x 1023 ] x x 1024
11 Na

46. 32. Find the number of molecules of water in 6 MOLES.
6[6.022 x 1023] x x 1024

47. 33. Find the number of caramels in 0.5 MOLES.
.5 x [6.022 x 1023 ] x 1023
Image Source: SStevens

48. 34. How many moles of caramels is 6.022x1023 of caramels? ___
Image Source: SStevens 2005

49. 35. How many moles of Starbursts is 6.022x1023 of Starbursts? ___

50. Avagadro is a bad boy!

51. 36. How many moles of Gobstoppers is 12.04x1023 of Gobstoppers? ___

52. 37. How many atoms of potassium make up one MOLE?
6.022 x 1023 19 K
39.10

53. 38. How many atoms of potassium make up 2 MOLES?
2 x [6.022 x 1023 ] x x 1024 19 K
39.10

54. 39. How many molecules of water make up 1 MOLE?
6.022 x 1023
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55. 40. How many molecules of water make up 5 MOLES?
5 x [6.022 x 1023 ] x x 1024

56. 41. How many moles are 6.022 x 1023 atoms of sodium? _____
Image source: SStevens 2002

57. 42. How many moles are 12.04 x 1023 atoms of carbon? _____
Image source: SStevens 2002

58. 43. How many moles are 18.06 x 1023 atoms of sodium? _____
Image source: SStevens 2002

59. 44. How many moles are 60.22 x 1023 atoms of sodium? _____
Image source: SStevens 2002

60. 45. How many moles are 6.022 x 1023 molecules of water? _____
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61. 46. How many moles are 12.04 x 1023 molecules of water? _____
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62. 47. How many moles are 30.10 x 1023 molecules of water? _____5
30.10 x = 5
6.022 x 1023
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63. Part 2

64. Mass
In addition to being able to tell the number of items in an MANU, you can now tell the mass of an MANU of Hershey’s Kisses, Jolly Ranchers, and caramels.

65. Number of items in package
Data Table 1
Name of the Items in the Package
Number of items in package
Mass of
package
Jolly Ranchers
Caramels
Hershey's Kisses 4
26.9 4
23.03 4
20.96

66. 48. Based on your measurements, the mass of 1 MANU of Hershey’s Kisses is ______ g.
20.96
Image Source: SStevens 2005

67. 49. The mass of 2 MANUS of Hershey’s Kisses is ______ g.
41.92
Image Source: SStevens 2005

68. 50. The mass of 1 MANU of Jolly Ranchers is ___ g.
26.9
Image Source: SStevens 2005

69. 51. The mass of 1 MANU of caramels is ____ g
23.03
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70. 52. The mass of 100 MANUS of Hershey’s Kisses is ____ g.
2096
Image Source: SStevens 2005

71. 53. The mass of 1/2 MANU of Hershey’s Kisses is _________ g.
10.48
Image Source: SStevens

72. 54.a. Complete the directions for finding total mass (MT) of a given number of MANUS (n), assuming you know the mass of a single MANU (m)
MT = m x n

73. 54.b. Complete the formula for finding total mass (MT) of a given number of items (z), assuming you know the mass of a single MANU (m)
MT = m x (z/4)

74. 55. The mass of 4 MANUS of Jolly Ranchers is _______ g.
107.6
Image Source: SStevens2005

75. 56. The mass of 0.5 MANUS of Jolly Ranchers is ______ g.
13.45
Image Source: SStevens 2005

76. 57. The mass of 100 MANUS of caramels is ________ g.
Image source: SStevens 2005

77. 58. The mass of 1/5 MANUS of caramels is ________ g.
4.606
Image source: SStevens 2005

78. 59. The mass of 60 MANUS of Hershey’s Kisses is ________ g.
1257.6
Image Source: SStevens

79. 60. The mass of 0.1 MANUS of Hershey’s Kisses is ________ g.
2.096
Image Source: SStevens 2005

80. 61. How would you calculate the number of MANUS if you know the mass of a package of Hershey’s Kisses?
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Divide total by mass of single MANU
e.g 260/20.96 = 12.40

81. 62. How would you calculate the number of MANUS if you know the mass of a package of caramels?
Image Source: SStevens 2005
198.5/23.03 = 8.62

82. 63. How would you calculate the number of MANUS if you know the mass of a package of Jolly Ranchers?
198/26.9 = 7.36

83. Molar Mass
Scientists use the Periodic Table to determine the mass of a mole of atom of an element.
For example, a mole of Iron (Fe) atoms would have a mass of 55.85g.

84. Amazing!

85. Periodic Table
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86. 64. The mass of 1 mole of Strontium (Sr) is ___ g.
87.62 38 Sr
87.62

87. 65. The mass of 1 mole of Lead (Pb) is ____ g.
207.2 82 Pb
207.2

88. 66. The mass of 1 mole of Nickel (Ni) is ____ g.
58.69 28 Ni
58.69

89. 67. The mass of 4 moles of Strontium (Sr) is ______g.
350.48 38 Sr
87.62

90. 68. The mass of 0.5 moles of Lead (Pb) is ____ g.
103.6 82 Pb
207.2

91. 69. The mass of 100 moles of (Ni) is ________ g. 28 Ni
58.69

92. Molar Mass
Scientists also use the Periodic Table to determine the molar mass (formula weight) of compounds.
The molar mass of the compound is the sum of the molar masses of the elements that make up the compound.

93. Potassium Chloride The molar mass of Potassium Chloride (KCl) is :
Potassium (K) g/mole
Chloride (Cl) g/mole
74.55 g/mole

94. Potassium Permanganate
The molar mass of KMnO4 is the sum of all the molar masses times the number of atoms of each element for the molecule (subscript).

95. Potassium Permanganate KMnO4
Potassium (K)
39.10 g/mole
Manganese (Mn)
54.94g/mole
Oxygen (O)
4 x [16.00 g/mole]
TOTAL
g/mole.

96. 70. The molar mass of 1 mole of Sodium Chloride (NaCl) is____ g.
58.44
Image source: SStevens 2002

97. 71. The molar mass of 1 mole of Lead Iodide (PbI2) is _____ g.
461.0

98. 72. The mass of 100 moles of Nickel Sulfide (NiS) is ________ g.

99. 73. The mass of 1 mole of is Glucose (C6H12O6) is ________ g.
Image source: SStevens 2002

100. Plants make approximately 24 kgs of glucose per person per year!

101. 74. The mass of 1 mole of is Sucrose (C12H24O12 ) _______ g.
306.31
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102. 75. The mass of 4 moles of Glucose (C6H12 O6) is _________ g.
Image source: SStevens 2002

103. Mole Conversions
In chemistry, the mole is the standard measurement of amount.
However, balances DO NOT give readings in moles. Balances give readings in grams.
So the problem is that, while we compare amounts of one substance to another using moles, we must also use grams, since this is the information we get from balances.

104. There are three steps to converting grams of a substance to moles.
1. Determine how many grams are given in the problem.
2. Calculate the molar mass of the substance.
3. Divide step one by step two.

105. The three steps above can be expressed in the following proportion:
Grams Moles = Molar Mass 1 Mole

106. Example #1 - Convert 25 grams of KMnO4 to moles.
Step One: The problem will tell you how many grams are present. Look . for the unit of grams. The problem gives us 25.0 grams. Step Two: You need to know the molar mass of the substance. The . , molar mass of KMnO4 is grams/mole. Potassium (K) = x 1 = g Manganese (Mn) = x 1 = g Oxygen (O) = x 4 = g g Step Three: You divide the grams given by the substance's molar mass . . (25.0/158.04) The answer of 0.16 mole has been rounded off.

107. Example #2 - Calculate how many moles are in 57.0 grams of Mg(NO3)2
1) 57.0 grams are given in the text of the problem. 2) The molar mass is 148 grams/mole. Mg (Magnesium) : 24 x 1=24 g N (Nitrogen) : 14 x 2=28 g O (Oxygen) : 16 x 6=96 g 3) Again you divide the grams by the substances molar mass (57.0 g/148 g). This answer has been rounded to 0.39 moles.

108. Practice Problems

109. 1. Calculate the moles present in: 2.00 grams of H2O
.11 moles water

110. 2. Calculate the moles present in: 75.57 grams of KBr
.635 moles KBr

111. 3. Calculate the moles present in: 100.0 grams of KClO4
.72 moles KClO4

112. 4. Calculate the moles present in: 225.5 grams of Sucrose (C12H24O12)
.63 moles Sucrose

113. 5. Calculate the moles present in: 350.0 grams of Glucose (C6H12O6)
1.943 moles Glucose

114. Calculate the mass of oxygen needed to react with 12 grams of magnesium.
Step 1: Write Ar values:
Mg = 24; O = 16
Step 2: Write the formula and balance it
Mg + O2  MgO (not balanced)
2Mg + O2  2MgO (balanced )
Step 3: Write the formula and balance it
48g of magnesium reacts with 32g of oxygen
Therefore, (12/48)x32 = 8g of oxygen needed! √

115. Calculate the amount of aluminium needed to react with 34g of oxygen in aluminium oxide.
(remember to work out the formula first!)
38.25 g

116. Homework

117. 1. Calculate the moles present in: 3.00 grams of NaCl

118. 2. Calculate the moles present in: 25.0 grams of NH3
1.47 moles NH3

119. 3. Calculate the moles present in: 16.0 grams of KCl
.21 moles KCl

120. 4. Calculate the moles present in: 30.25 grams of BeCl2
.38 moles KCl

121. 5. Calculate the moles present in: 175.25 grams of Li2S
3.81 moles Li2S

122. 6. Calculate the moles present in: 75.62 grams of CO2
1.72 moles CO2

123. 7. Calculate the moles present in: 56.5 grams of H2O
3.14 moles H2O

124. 8. Calculate the moles present in: 22.6 grams of CH3COOH
.38 moles CH3COOH

125. 9. Calculate the moles present in: 18.4 grams of AgCl
.13 moles AgCl

126. 10. Calculate the moles present in: 68.3 grams of HCN
2.53 moles HCN