# Moles and Molar Mass

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```					         Chapter 9

The Mole
Calculations Using Molar Mass

Timberlake LecturePLUS   1
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

Timberlake LecturePLUS           2
A Mole of Particles

Contains 6.02 x 1023 particles

1 mole C       = 6.02 x 1023 C atoms
1 mole H2O     = 6.02 x 1023 H2O molecules
1 mole NaCl    = 6.02 x 1023 Na+ ions and
6.02 x 1023 Cl– ions
Timberlake LecturePLUS     3
More Examples of Moles

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

6.02 x 1023 particles
1 mole
or

1 mole
6.02 x 1023 particles

Timberlake LecturePLUS   5
Learning Check M1
Suppose we invented a new collection unit
called a mep. One mep contains 8 objects.
A. How many paper clips in 1 mep?
1) 1            2) 4                 3) 8
B. How many oranges in 2.0 meps?
1) 4            2) 8                 3) 16
C. How many meps contain 40 gummy bears?
1) 5            2) 10                3) 20
Timberlake LecturePLUS           6
Solution M1

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
Timberlake LecturePLUS   7
Learning Check M2
1. Number of atoms in 0.500 mole of Al
1) 500 Al atoms
2) 6.02 x 1023 Al atoms
3) 3.01 x 1023 Al atoms
2.Number of moles of S in 1.8 x 1024
S atoms
1) 1.0 mole S atoms
2) 3.0 mole S atoms
3) 1.1 x 1048 mole S atoms
Timberlake LecturePLUS    8
Solution M2
1. Number of atoms in 0.500 mol of Al
3) 3.01 x 1023 Al atoms
0.500 mol Al x 6.02 x 1023 Al atoms
1 mol Al

2. Number of moles of S if a sample of S
contains 4.50 x 1024 S atoms
2) 3.0 mole S atoms
4.50 x 1024 S atoms x    1 mol S
6.02 x 1023 S atoms
Timberlake LecturePLUS       9
Molar Mass
   Number of grams in 1 mole
   Equal to the numerical value of the atomic
mass
1 mole of C atoms                   =   12.0 g
1 mole of Mg atoms                  =   24.3 g
1 mole of Cu atoms                  =   63.5 g

Timberlake LecturePLUS                10
Learning Check M3

Give the molar mass to 0.1 g
A. 1 mole of Br atoms                     =   ________

B. 1 mole of Sn atoms                     =   ________

Timberlake LecturePLUS              11
Solution M3

Give the molar mass to 0.1 g
A. 1 mole of Br atoms =                   79.9 g/mole
B. 1 mole of Sn atoms =                   118.7 g/mole

Timberlake LecturePLUS                  12
Molar Mass of Compounds
Mass in grams of 1 mole equal numerically to
the sum of the atomic masses
1 mole of CaCl2     = 111.1 g/mole
1 mole Ca x 40.1 g/mole
+ 2 moles Cl x 35.5 g/mole

1 mole of N2O4     = 74.0 g/mole
2 moles N x 14.0 g/mole
+ 4 moles O x 16.0 g/mole
Timberlake LecturePLUS        13
Learning Check M4

A. 1 mole of K2O                            = ______g

B. 1 mole of antacid Al(OH)3                = ______g

Timberlake LecturePLUS               14
Solution M4

A. 1 mole of K2O                            = 94.2 g
2 K x 39.1 g/mole + 1 O x 16.0 g/mole

B. 1 mole of antacid Al(OH)3                = 78.0 g
1 Al x 27.0 g/mole + 3 O x 16.0 g/mole
+ 3 x 1.0
Timberlake LecturePLUS          15
Learning Check M5

Prozac, C17H18F3NO, is a widely used
antidepressant that inhibits the uptake of
serotonin by the brain. It has a molar mass
of
1) 40.0 g/mole
2) 262 g/mole
3) 309 g/mole

Timberlake LecturePLUS   16
Solution M5

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)

Timberlake LecturePLUS     17
Learning Check M6

What is the percent carbon in C5H8NO4
(MSG monosodium glutamate), a
compound used to flavor foods and
tenderize meats?
1) 8.22 %C
2) 24.3 %C
3) 41.1 %C

Timberlake LecturePLUS    18
Solution M6

Molar mass = 146.0 g/mole
% = total g C          x 100
total g compound

= 60.0 g C        x 100 = 41.1% C
146.0 g MSG

Timberlake LecturePLUS   19
Molar Mass Factors for CH4
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 =          16.0 g

16.0 g CH4     and                  1 mole CH4
1 mole CH4                         16.0 g CH4

Timberlake LecturePLUS            20
Learning Check M7

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                   1 mole acetic acid

Timberlake LecturePLUS                  21
Solution M7

Acetic acid CH3COOH is the acid in vinegar . It
has a molar mass of 60.0 g/mole.

1 mole of acetic acid           =        60.0 g

1 mole acetic acid        or         60.0 g acetic acid
60.0 g acetic acid                   1 mole acetic acid

Timberlake LecturePLUS              22
Calculations with Molar Mass

molar mass
Grams                            Moles

Timberlake LecturePLUS           23
Moles and Grams

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

Timberlake LecturePLUS   24
1. Molar mass of Al
1 mole Al = 27.0 g Al
2. Conversion factors for Al
27.0g Al     or    1 mol Al
1 mol Al           27.0 g Al

3. Setup
3.00 moles Al x     27.0 g Al
1 mole Al

Timberlake LecturePLUS   25
Learning Check M9

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?

Timberlake LecturePLUS      26
Solution M9

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

= 0.765 mole aspartame

Timberlake LecturePLUS         27

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