Transcript CH_5_1_The_Mole

Chapter 5
Chemical Quantities and Reactions
1
5.1
The Mole
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
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Counting Units
2
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
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Avogadro's Number
3
Small particles such as atoms, molecules, and ions are
counted using the mole.
1 mole = 6.02 x 1023 items
Avogadro’s number
602 000 000 000 000 000 000 000 = 6.02 x 1023
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Mole of Atoms
4
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
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Number of Particles in One-Mole
Samples
5
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Avogadro's Number
6
Avogadro’s number, 6.02 x 1023, can be written as an
equality and as two conversion factors.
Equality:
1 mole = 6.02 x 1023 particles
Conversion Factors:
6.02 x 1023 particles and
1 mole
1 mole
6.02 x 1023 particles
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Guide to Calculating Atoms or
Molecules
7
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
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Converting Moles to Particles
8
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: 0.50 mole of CO2
Needed: molecules of CO2
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Converting Moles to Particles
9
Step 2 Write a plan to convert moles to atoms or molecules:
Avogadro’s number
moles of CO2
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
1 mole CO2
1 mole CO2
6.02 x 1023 CO2 molecules
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
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Converting Moles to Particles
10
Step 4 Set up the problem to calculate the number of particles.
0.50 mole CO2 x 6.02 x 1023 molecules CO2
1 mole CO2
= 3.01 x 1023 molecules of CO2
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Learning Check
11
The number of atoms in 2.0 mole of Al atoms is:
A. 2.0 Al atoms
B. 3.0 x 1023 Al atoms
C. 1.2 x 1024 Al atoms
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Solution
12
The number of atoms in 2.0 moles of Al atoms is:
Step 1 State the needed and given quantities:
Given: 2.0 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
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Solution
13
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
1 mole A
1 mole Al
6.02 x 1023 atoms Al
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Solution
14
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. 2.0 moles Al x 6.02 x 1023 Al atoms
1 mole Al
= 1.2 x 1024 Al atoms
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Learning Check
15
The number of moles of S in 1.8 x 1024 atoms of S is:
A. 1.0 mole of S atoms
B. 3.0 moles of S atoms
C. 1.1 x 1048 moles of S atoms
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Solution
16
The number of moles of S in 1.8 x 1024 atoms of S is:
Step 1 State the needed and given quantities:
Given: 1.8 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
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Solution
17
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
1 mole S
1 mole S
6.02 x 1023 atoms S
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Solution
18
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
1 mole S
6.02 x 1023 S atoms
= 3.0 moles of S atoms
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Moles of Elements in a Formula
19
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Moles of Elements in a Formula
20
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
1 mole:
9 moles of C 8 moles of H
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
4 atoms of O
4 moles of O
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Moles of Elements in a Formula
21
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
1 mole C9H8O4
8 moles H
1 mole C9H8O4
4 moles O
1 mole C9H8O4
1 mole C9H8O4
9 moles C
1 mole C9H8O4
8 moles H
1 mole C9H8O4
4 moles O
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Learning Check
22
How many atoms of O are in 0.150 mole of aspirin, C9H8O4?
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Solution
23
Step 1 State the needed and given quantities:
Given: 0.150 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
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Atoms of O
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Solution
24
Step 3 Use Avogadro’s number to write conversion factors.
Subscript factor: 1 mole of C9H8O4 = 4 moles of O
1 mole C9H8O4
4 moles O
and
4 moles O
1 mole C9H8O4
Avogadro’s number:
1 mole of O = 6.02 x 1023 atoms of O
1 mole O
and
6.02 x 1023 atoms O
6.02 x 1023 atoms O
1 mole O
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Solution
25
Step 4 Set up the problem to calculate the number of particles.
0.150 mole C9H8O4 x 4 mole O x 6.02 x 1023 atoms O
1 mole C9H8O4
1 mole O
= 3.61 x 1023 atoms of O
Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.