1 Chapter 5 Chemical Reactions and Quantities 5.5 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 is a collection that contains the same number of particles as there are carbon atoms in 12.0 g of carbon x atoms of an element (Avogadro’s number). 1 mole element Number of Atoms 1 mole C = 6.02 x C atoms 1 mole Na = 6.02 x Na atoms 1 mole Au= 6.02 x Au atoms A Mole of Atoms

4 A mole of a covalent compound has Avogadro’s number of molecules. 1 mole CO 2 = 6.02 x CO 2 molecules 1 mole H 2 O = 6.02 x H 2 O molecules of an ionic compound contains Avogadro’s number of formula units. 1 mole NaCl = 6.02 x NaCl formula units 1 mole K 2 SO 4 = 6.02 x K 2 SO 4 formula units A Mole of a Compound

5 Samples of One Mole Quantities 1 mole C=6.02 x C atoms 1 mole Al=6.02 x Al atoms 1 mole S=6.02 x S atoms 1 mole H 2 O=6.02 x H 2 O molecules 1 mole CCl 4 =6.02 x CCl 4 molecules

6 Avogadro’s number 6.02 x can be written as an equality and two conversion factors. Equality: 1 mole = 6.02 x particles Conversion Factors: 6.02 x particles and 1 mole 1 mole6.02 x 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 mole Cu? 0.50 mole Cu x 6.02 x Cu atoms 1 mole Cu = 3.0 x 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 molecules CO 2 ? 2.50 x molecules CO 2 x 1 mole CO x molecules CO 2 = 4.15 mole CO 2

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

10 Solution A. The number of atoms in 2.0 mole Al is 2.0 mole Al x 6.02x10 23 Al atoms = 1.2 x Al atoms 1 mole Al Avogadro’s Number B. The number of moles of S in 1.8 x atoms S is 1.8 x atoms S x 1 mole S 6.02 x S atoms Avogadro’s Number = 3.0 moles of S atoms

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

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

13 Factors from Subscripts The subscripts are used to write conversion factors for moles of each element in 1 mole compound. For aspirin C 9 H 8 O 4, the following factors can be written: 9 mole C 8 mole H 4 mole O 1 mole C9H8O4 1 mole C9H8O4 1 mole C9H8O4 and 1 mole C9H8O4 1 mole C9H8O4 1 mole C9H8O4 9 mole C 8 mole H 4 mole O

14 Learning Check A. How many mole O are in mole aspirin C 9 H 8 O 4 ? B. How many O atoms are in mole aspirin C 9 H 8 O 4 ?

15 Solution A. How many mole O are in mole aspirin C 9 H 8 O 4 ? mole C 9 H 8 O 4 x 4 mole O = mole O 1 mole C 9 H 8 O 4 subscript factor B. How many O atoms are in mole aspirin C 9 H 8 O 4 ? mole C 9 H 8 O 4 x 4 mole O x 6.02 x O atoms 1 mole C 9 H 8 O 4 1 mole O subscript Avogadro’s factor Number = 3.61 x O atoms