 # 1 Chapter 7 Chemical Quantities 7.2 The Mole Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings.

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1 Chapter 7 Chemical Quantities 7.2 The Mole Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

2 Collection Terms A collection term states a specific number of items. 1 dozen donuts = 12 donuts 1 ream of paper = 500 sheets 1 case = 24 cans Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

3 A mole (mol) is a collection that contains: The same number of particles as there are carbon atoms in 12.01 g of carbon 6.022 x 10 23 atoms of an element (Avogadro’s number). 1 Mol element Number of Atoms 1 mol C = 6.022 x 10 23 C atoms 1 mol Na = 6.022 x 10 23 Na atoms 1 mol Au= 6.022 x 10 23 Au atoms A Mole of Atoms

4 A mole Of a covalent compound has Avogadro’s number of molecules 1 mol CO 2 = 6.022 x 10 23 CO 2 molecules 1 mol H 2 O = 6.022 x 10 23 H 2 O molecules Of an ionic compound contains Avogadro’s number of formula units 1 mol NaCl = 6.022 x 10 23 NaCl formula units 1 mol K 2 SO 4 = 6.022 x 10 23 K 2 SO 4 formula units A Mole of a Compound

5 Samples of One-Mole Quantities

6 Avogadro’s number 6.022 x 10 23 can be written as an equality and two conversion factors. Equality: 1 mol = 6.022 x 10 23 particles Conversion Factors: 6.022 x 10 23 particles and 1 mol 1 mol6.022 x 10 23 particles Avogadro’s Number

7 Using Avogadro’s Number Avogadro’s number is used to convert Moles of a substance to Particles. How many Cu atoms are in 0.50 mol Cu? 0.50 mol Cu x 6.022 x 10 23 Cu atoms 1 mol Cu = 3.0 x 10 23 Cu atoms Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

8 Using Avogadro’s Number Avogadro’s number is used to convert Particles of a substance to Moles. How many moles of CO 2 are in 2.50 x 10 24 CO 2 molecules? 2.50 x 10 24 CO 2 x 1 mol CO 2 6.022 x 10 23 CO 2 = 4.15 mol CO 2

9 1. The number of atoms in 2.0 mol Al is A. 2.0 Al atoms B. 3.0 x 10 23 Al atoms C. 1.2 x 10 24 Al atoms 2. The number of moles of S in 1.8 x 10 24 atoms S is A. 1.0 mol S atoms B. 3.0 mol S atoms C. 1.1 x 10 48 mol S atoms Learning Check

10 C. 1.2 x 10 24 Al atoms 2.0 mol Al x 6.022 x 10 23 Al atoms 1 mol Al B. 3.0 mol S atoms 1.8 x 10 24 S atoms x 1 mol S 6.022 x 10 23 S atoms Solution

11 Subscripts and Moles The subscripts in a formula state The relationship of atoms in the formula. The moles of each element in 1 mol of compound. Glucose C 6 H 12 O 6 In 1 molecule: 6 atoms C 12 atoms H6 atoms O In 1 mol: 6 mol C 12 mol H 6 mol O

12 Subscripts State Atoms and Moles 9 mol C 8 mol H 4 mol O

13 Factors from Subscripts The subscripts are used to write conversion factors for moles of each element in 1 mol compound. For aspirin C 9 H 8 O 4, the following factors can be written: 9 mol C 8 mol H 4 mol O 1 mol C 9 H 8 O 4 1 mol C 9 H 8 O 4 1 mol C 9 H 8 O 4 and 1 mol C 9 H 8 O 4 1 mol C 9 H 8 O 4 1 mol C 9 H 8 O 4 9 mol C 8 mol H 4 mol O

14 Learning Check How many O atoms are in 0.150 mol aspirin C 9 H 8 O 4 ?

15 Solution How many O atoms are in 0.150 mol aspirin C 9 H 8 O 4 ? 0.150 mol C 9 H 8 O 4 x 4 mol O x 6.022 x 10 23 O atoms 1 mol C 9 H 8 O 4 1 mol O subscript Avogadro’s factor Number = 3.61 x 10 23 O atoms