1. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Chapter 5 Chemical Quantities and Reactions 5.2 Molar Mass 1

2. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Molar Mass The molar mass is the mass of 1 mole of an element is the atomic mass expressed in grams 2

3. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Molar Mass from Periodic Table Molar mass is the atomic mass expressed in grams. 1 mole of Ag 1 mole of C 1 mole of S = 107.9 g of Ag = 12.0 g of C = 32.1 g of S 3

4. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Give the molar mass for each element (to the tenths place). A. 1 mole of K atoms =________ B. 1 mole of Sn atoms =________ C. 1 mole of Ca atoms=________ 4

5. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Give the molar mass for each element (to the tenths place). A. 1 mole of K atoms = 39.1 g of K B. 1 mole of Sn atoms =118.7 g of Sn C. 1 mole of Ca atoms= 40.0 g of Ca 5

6. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Guide to Calculating Molar Mass 6

7. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Molar Mass of the Compound C 2 H 6 O To calculate the molar mass of C 2 H 6 O: Step 1 Obtain the molar mass of each element. 1 mole of C = 12.0 g of C 1 mole of H = 1.01 g of H 1 mole of O = 16.0 g of O 7

8. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Molar Mass of the Compound C 2 H 6 O Step 2 Multiply each molar mass by the number of moles (subscripts) in the formula. 2 moles C x 12.0 g C = 24.0 g of C 1 mole C 6 moles H x 1.01 g H = 6.06 g of H 1 mole H 1 mole O x 16.0 g O = 16.0 g of O 1 mole O 8

9. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Molar Mass of the Compound C 2 H 6 O Step 3 Calculate the molar mass by adding the masses of the elements. 2 moles of C = 24.0 g of C 6 moles of H = 6.06 g of H 1 mole of O = 16.0 g of O Molar mass of C 2 H 6 O = 46.1 g of C 2 H 6 O 9

10. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. One-Mole Quantities 10

11. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check What is the molar mass of each compound? A. K 2 O B. Al(OH) 3 11

12. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution What is the molar mass of each compound? Step 1 Obtain the molar mass of each element. A. K 2 OK = 39.1 g/mole O = 16.0 g/mole B. Al(OH) 3 Al= 27.0 g/mole O= 16.0 g/mole H = 1.01 g/mole 12

13. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution What is the molar mass of each compound? Step 2 Multiply each molar mass by the number of moles (subscripts) in the formula. A. K 2 O 2 moles K x 39.1 g K = 78.2 g of K 1 mole K 1 mole O x 16.0 g O = 16.0 g of O 1 mole O 13

14. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution What is the molar mass of each compound? Step 2 Multiply each molar mass by the number of moles (subscripts) in the formula. B. Al(OH) 3 1 mole Al x 27.0 g Al = 27.0 g of Al 1 mole Al 3 moles O x 16.0 g O = 48.0 g of O 1 mole O 3 moles H x 1.01 g H = 3.03 g of H 1 mole H 14

15. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution What is the molar mass of each compound? Step 3 Calculate the molar mass by adding the masses of the elements. A. K 2 O2 moles of K = 78.2 g of C 1 mole of O = 16.0 g of O Molar mass of K 2 O = 94.2 g of K 2 O B. Al(OH) 3 1 mole of Al = 27.0 g of Al 3 moles of O = 48.0 g of O 3 moles of H = 3.03 g of H Molar mass of Al(OH) 3 = 78.0 g of Al(OH) 3 15

16. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Prozac, C 17 H 18 F 3 NO, is an antidepressant that inhibits the uptake of serotonin by the brain. What is the molar mass of Prozac? A. 40.1 g/mole B. 262 g/mole C. 309 g/mole 16

17. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Step 1 Obtain the molar mass of each element. 1 mole of C = 12.0 g of C 1 mole of H = 1.01 g of H 1 mole of F = 19.0 g of F 1 mole of N = 14.0 g of N 1 mole of O = 16.0 g of O 17

18. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Step 2 Multiply each molar mass by the number of moles (subscripts) in the formula. 17 moles C x 12.0 g = 204 g of C 1 mole C 18 moles H x 1.01 g = 18.2 g of H 1 mole H 3 moles F x 19.0 g = 57.0 g of F 1 mole F 1 mole N x 14.0 g = 14.0 g of N 1 mole N 1 mole O x 16.0 g = 16.0 g of O 1 mole O 18

19. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Step 3 Calculate the molar mass by adding the masses of the elements: 1 mole of C 17 H 18 F 3 NO = 309 g of C 17 H 18 F 3 NO 19

20. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Calculations Using Molar Mass Molar mass conversion factors are fractions (ratios) written from the molar mass. relate grams and moles of an element or compound. for methane, CH 4, used in gas stoves and gas heaters, is 1 mole of CH 4 = 16.0 g of CH 4 (molar mass equality) Conversion factors: 16.0 g CH 4 and 1 mole CH 4 1 mole CH 4 16.0 g CH 4 20

21. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Guide to Calculating Moles from Mass 21

22. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Converting Mass to Moles of Compound NaCl A box of table salt, NaCl, contains 737 g of NaCl. How many moles of NaCl are in the box? 22

23. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Converting Mass to Moles of Compound NaCl A box of table salt, NaCl, contains 737 g of NaCl. How many moles of NaCl are in the box? Step 1 State the given and needed quantities. Given: 737 g of NaCl Need:moles of NaCl Step 2 Write a plan to convert grams to moles. molar mass Grams of NaCl Moles of NaCl 23

24. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Converting Mass to Moles of Compound NaCl Step 3 Determine the molar mass and write conversion factors. Molar Mass 1 mole Na x 23.0 g Na = 23.0 g of Na 1 mole Na 1 mole Cl x 35.5 g Cl = 35.5 g of Cl 1 mole Cl 58.5 g of NaCl Conversion Factors 1 mole of NaCl = 58.5 g of NaCl 58.5 g NaCl and 1 mole NaCl 1 mole NaCl 58.5 g NaCl 24

25. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Converting Mass to Moles of Compound NaCl Step 4 Set up the problem to convert grams to moles. 737 g NaCl x 1 mole NaCl = 12.6 moles of NaCl 58.5 g NaCl 25

26. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Map: Mass – Moles – Particles 26

27. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Allyl sulfide, C 6 H 10 S, is a compound that has the odor of garlic. How many moles of C 6 H 10 S are in 225 g? 27

28. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Step 1 State the given and needed quantities. Given: 225 g of C 6 H 10 S Need:moles of C 6 H 10 S Step 2 Write a plan to convert grams to moles. molar mass Grams of C 6 H 10 S Moles of C 6 H 10 S 28

29. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Step 3 Determine the molar mass and write conversion factors. Molar mass 6 moles C x 12.0 g C = 76.0 g of C 1 mole C 10 moles H x 1.01 g H = 10.1 g of H 1 mole H 1 mole S x 32.1 g S = 32.1 g of S 1 mole S = 114.2 g of C 6 H 10 S 29

30. Chemistry An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Step 3 Determine the molar mass and write conversion factors. Conversion Factors 1 mole of C 6 H 10 S = 114.2 g of C 6 H 10 S 114.2 g C 6 H 10 S and 1 mole C 6 H 10 S 1 mole C 6 H 10 S 114.2 g C 6 H 10 S Step 4 Set up the problem to convert grams to moles. 225 g C 6 H 10 S x 1 mole C 6 H 10 S 114.2 g C 6 H 10 S = 19.7 moles of C 6 H 10 S 30