1. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Chapter 5 Chemical Quantities and Reactions 5.1 The Mole 1

2. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Counting Units 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 2

3. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Avogadro's Number Small particles such as atoms, molecules, and ions are counted using the mole. 1 mole = 6.02 x 10 23 items Avogadro’s number 602 000 000 000 000 000 000 000 = 6.02 x 10 23 3

4. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Mole of Atoms 1 mole of an element = 6.02 x 10 23 atoms of that element 1 mole of carbon= 6.02 x 10 23 atoms of carbon 1 mole of sodium= 6.02 x 10 23 atoms of sodium 4

5. 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

6. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Avogadro's Number Avogadro’s number, 6.02 x 10 23, can be written as an equality and as two conversion factors. Equality: 1 mole = 6.02 x 10 23 particles Conversion Factors: 6.02 x 10 23 particles and 1 mole 1 mole 6.02 x 10 23 particles 6

7. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Guide to Calculating Atoms or Molecules 7

8. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Converting Moles to Particles Avogadro’s number is used to convert moles of a substance to particles. How many CO 2 molecules are in 0.50 mole of CO 2 ? Step 1 State the needed and given quantities: Given: 0.50 mole of CO 2 Needed: molecules of CO 2 8

9. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Converting Moles to Particles Step 2 Write a plan to convert moles to atoms or molecules: Avogadro’s number moles of CO 2 molecules of CO 2 Step 3 Use Avogadro’s number to write conversion factors. 1 mole of CO 2 = 6.02 x 10 23 molecules of CO 2 6.02 x 10 23 CO 2 molecules and 1 mole CO 2 1 mole CO 2 6.02 x 10 23 CO 2 molecules 9

10. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Converting Moles to Particles Step 4 Set up the problem to calculate the number of particles. 0.50 mole CO 2 x 6.02 x 10 23 molecules CO 2 1 mole CO 2 = 3.01 x 10 23 molecules of CO 2 10

11. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check The number of atoms in 2.0 mole of Al atoms is: A. 2.0 Al atoms B. 3.0 x 10 23 Al atoms C. 1.2 x 10 24 Al atoms 11

12. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution 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 12

13. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution 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 10 23 atoms of Al 6.02 x 10 23 atoms Al and 1 mole A 1 mole Al 6.02 x 10 23 atoms Al 13

14. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution 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 10 23 Al atoms 1 mole Al = 1.2 x 10 24 Al atoms 14

15. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check The number of moles of S in 1.8 x 10 24 atoms of S is: A. 1.0 mole of S atoms B. 3.0 moles of S atoms C. 1.1 x 10 48 moles of S atoms 15

16. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution The number of moles of S in 1.8 x 10 24 atoms of S is: Step 1 State the needed and given quantities: Given: 1.8 x 10 24 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 16

17. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution The number of moles of S in 1.8 x 10 24 atoms of S is: Step 3 Use Avogadro’s number to write conversion factors. 1 mole S = 6.02 x 10 23 atoms of S 6.02 x 10 23 atoms S and 1 mole S 1 mole S 6.02 x 10 23 atoms S 17

18. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution The number of moles of S in 1.8 x 10 24 atoms of S is: Step 4 Set up the problem to calculate the number of particles. B. 1.8 x 10 24 S atoms x 1 mole S 6.02 x 10 23 S atoms = 3.0 moles of S atoms 18

19. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Moles of Elements in a Formula 19

20. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Moles of Elements in a Formula The subscripts in a formula show: the relationship of atoms in the formula the moles of each element in 1 mole of compound Aspirin C 9 H 8 O 4 1 molecule: 9 atoms of C 8 atoms of H 4 atoms of O 1 mole: 9 moles of C 8 moles of H 4 moles of O 20

21. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Moles of Elements in a Formula Subscripts are used to write conversion factors for moles of each element in 1 mole of a compound. For aspirin, C 9 H 8 O 4, the possible conversion factors are: 9 moles C 8 moles H 4 moles O 1 mole C 9 H 8 O 4 1 mole C 9 H 8 O 4 1 mole C 9 H 8 O 4 9 moles C 8 moles H 4 moles O 21

22. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check How many atoms of O are in 0.150 mole of aspirin, C 9 H 8 O 4 ? 22

23. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Step 1 State the needed and given quantities: Given: 0.150 mole of C 9 H 8 O 4 Need: molecules of C 9 H 8 O 4 Step 2 Write a plan to convert moles to atoms or molecules: Moles of aspirin Moles of O Atoms of O 23

24. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Step 3 Use Avogadro’s number to write conversion factors. Subscript factor: 1 mole of C 9 H 8 O 4 = 4 moles of O 1 mole C 9 H 8 O 4 and 4 moles O 4 moles O 1 mole C 9 H 8 O 4 Avogadro’s number: 1 mole of O = 6.02 x 10 23 atoms of O 1 mole O and 6.02 x 10 23 atoms O 6.02 x 10 23 atoms O 1 mole O 24

25. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Step 4 Set up the problem to calculate the number of particles. 0.150 mole C 9 H 8 O 4 x 4 mole O x 6.02 x 10 23 atoms O 1 mole C 9 H 8 O 4 1 mole O = 3.61 x 10 23 atoms of O 25