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Chapter 3
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1 trio = 3 singers
1 six-pack Cola = 6 cans Cola drink
1 dozen donuts = 12 donuts
1 gross of pencils = 144 pencils
Collection Terms
3
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
A Moles of Particles
4
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
Examples of Moles
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6.02 x 1023 particles
1 mole
or
1 mole
6.02 x 1023 particles
Avogadro’s Number
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 = 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 = 6.0221415 x 1023
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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
Learning Check
9
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
Solution
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1. Number of atoms in 0.500 mole of Al1) 500 Al atoms
2) 6.02 x 1023 Al atoms3) 3.01 x 1023 Al atoms
2.Number of moles of S in 1.8 x 1024 S atoms1) 1.0 mole S atoms2) 3.0 mole S atoms3) 1.1 x 1048 mole S atoms
Learning Check
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1. Number of atoms in 0.500 mol of Al3) 3.01 x 1023 Al atoms
0.500 mol Al x 6.02 x 1023 Al atoms1 mol Al
2. Number of moles of S if a sample of S contains 1.80 x 1024 S atoms2) 3.0 mole S atoms
1.80 x 1024 S atoms x 1 mol S 6.02 x 1023 S atoms
Solution
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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
Molar Mass
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Give the molar mass to 0.1 g
A. 1 mole of Br atoms = ________
B. 1 mole of Sn atoms = ________
Learning Check
14
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
Solution
15
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 = 92.0 g/mole
2 moles N x 14.0 g/mole + 4 moles O x 16.0 g/mole
Molar Mass of Compounds
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A. 1 mole of K2O = ______g
B. 1 mole of antacid Al(OH)3 = ______g
Learning Check
17
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
Solution
18
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
Learning Check
19
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)
Solution
20
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
Learning Check
21
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
Solution
22
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
Molar Mass Factors
23
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
Learning Check
24
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 acetic acid
1 mole acetic acid or 60.0 g acetic acid
60.0 g acetic acid 1 mole acetic acid
Solution
25
molar mass
Grams Moles
Calculations with Molar Mass
26
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
Moles and Grams
27
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
Answer = 81.0 g Al
28
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?
Learning Check
29
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
Solution