1. General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 6.5 Molar Mass Chapter 6 Chemical Reactions and Quantities © 2013 Pearson Education, Inc. Lectures

2. © 2013 Pearson Education, Inc. Chapter 6, Section 5 2 Molar mass is  the mass of one mole of a substance.  the number of grams that equals the atomic mass of that element. Molar Mass Molar mass is rounded to the tenths (0.1 g) place for use in this text.

3. © 2013 Pearson Education, Inc. Chapter 6, Section 5 3 Give the molar mass of the following elements to the nearest 0.1 g. 1. K= ________ 2. Sn= ________ 3. Si= ________ Learning Check

4. © 2013 Pearson Education, Inc. Chapter 6, Section 5 4 Solution Give the molar mass of the following elements to the nearest 0.1 g. 1. K= 39.1 g 2. Sn= 118.7 g 3. Si= 28.1 g

5. © 2013 Pearson Education, Inc. Chapter 6, Section 5 5 Guide to Calculating Molar Mass

6. © 2013 Pearson Education, Inc. Chapter 6, Section 5 6 Molar Mass of CaCl 2 We calculate the molar mass of CaCl 2 to the nearest 0.1 g as follows. Analyze the Problem. Step 1 Obtain the molar mass of each element. GivenNeed formula unit CaCl 2 molar mass of Ca, Cl; CaCl 2

7. © 2013 Pearson Education, Inc. Chapter 6, Section 5 7 Molar Mass of CaCl 2 We calculate the molar mass of CaCl 2 to the nearest 0.1 g as follows. Step 2 Multiply each molar mass by the number of moles (subscript) in the formula. Grams from 1 mole of Ca Grams from 2 moles of Cl

8. © 2013 Pearson Education, Inc. Chapter 6, Section 5 8 Molar Mass of CaCl 2 We calculate the molar mass of CaCl 2 to the nearest 0.1 g as follows. Step 3 Calculate the molar mass by adding the masses of the elements.

9. © 2013 Pearson Education, Inc. Chapter 6, Section 5 9 Learning Check Determine the molar mass of K 3 PO 4 to 0.1 g.

10. © 2013 Pearson Education, Inc. Chapter 6, Section 5 10 Solution Determine the molar mass of K 3 PO 4 to 0.1 g. Analyze the Problem. Step 1 Obtain the molar mass of each element. GivenNeed formula unit K 3 PO 4 molar mass of K, P, O; molar mass of K 3 PO 4

11. © 2013 Pearson Education, Inc. Chapter 6, Section 5 11 Solution Determine the molar mass of K 3 PO 4 to 0.1 g. Step 2 Multiply each molar mass by the number of moles (subscript) in the formula. Grams from 3 moles of K

12. © 2013 Pearson Education, Inc. Chapter 6, Section 5 12 Solution Determine the molar mass of K 3 PO 4 to 0.1 g. Step 3 Calculate the molar mass by adding the masses of the elements.

13. © 2013 Pearson Education, Inc. Chapter 6, Section 5 13 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. 40.0 g/mole B. 262 g/mole C. 309 g/mole Learning Check

14. © 2013 Pearson Education, Inc. Chapter 6, Section 5 14 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? Analyze the Problem Solution GivenNeed molecular formula for Prozac, C 17 H 18 F 3 NO molar mass of C, H, F, N, O molar mass of C 17 H 18 F 3 NO

15. © 2013 Pearson Education, Inc. Chapter 6, Section 5 15 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? Step 1 Obtain the molar mass of each element. C 12.0 g/mole N 14.0 g/mole F 19.0 g/mole O 16.0 g/mole H 1.0 g/mole Solution

16. © 2013 Pearson Education, Inc. Chapter 6, Section 5 16 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? Step 2 Multiply each molar mass by the number of moles (subscript) in the formula. Solution

17. © 2013 Pearson Education, Inc. Chapter 6, Section 5 17 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? Step 3 Calculate the molar mass by adding the masses of the elements. Solution

18. © 2013 Pearson Education, Inc. Chapter 6, Section 5 18 One-Mole Quantities 32.1 g 55.9 g 58.5 g 294.2 g 342.3 g

19. © 2013 Pearson Education, Inc. Chapter 6, Section 5 19 Methane (CH 4 ), known as natural gas, is used in gas stoves and gas heaters. 1 mole of CH 4 = 16.0 g of CH 4 The molar mass of methane can be written as conversion factors Conversion Factors from Molar Mass

20. © 2013 Pearson Education, Inc. Chapter 6, Section 5 20 Calculations Using Molar Mass

21. © 2013 Pearson Education, Inc. Chapter 6, Section 5 21 How many moles are present in a 65.1 g sample of KCl? Step 1 State the given and needed quantities. Analyze the Problem. Step 2 Write a plan to convert grams to moles. grams of KCl Molar Mass moles of KCl Converting Mass to Moles, KCl GivenNeed 65.1 g of KClmoles of KCl

22. © 2013 Pearson Education, Inc. Chapter 6, Section 5 22 How many moles are present in a 65.1 g sample of KCl? Step 3 Determine the molar mass and write conversion factors. Step 4 Set up the problem to convert grams to moles. Converting Mass to Moles, KCl 1 mole of KCl = 74.6 g of KCl

23. © 2013 Pearson Education, Inc. Chapter 6, Section 5 23 Acetic acid, C 2 H 4 O 2, gives the sour taste to vinegar. Calculate the moles of acetic acid present in a 25.8 g sample. Learning Check

24. © 2013 Pearson Education, Inc. Chapter 6, Section 5 24 Acetic acid, C 2 H 4 O 2, gives the sour taste to vinegar. Calculate the moles of acetic acid present in a 25.8 g sample. Step 1 State the given and needed quantities. Analyze the Problem. Step 2 Write a plan to convert grams to moles. grams of C 2 H 4 O 2 Molar Mass moles C 2 H 4 O 2 Solution GivenNeed 25.8 g acetic acid, C 2 H 4 O 2 moles of C 2 H 4 O 2

25. © 2013 Pearson Education, Inc. Chapter 6, Section 5 25 Acetic acid, C 2 H 4 O 2, gives the sour taste to vinegar. Calculate the moles of acetic acid present in a 25.8 g sample. Step 3 Determine the molar mass and write conversion factors. 1 mole of C 2 H 4 O 2 = 60.0 g of C 2 H 4 O 2 Solution

26. © 2013 Pearson Education, Inc. Chapter 6, Section 5 26 Acetic acid, C 2 H 4 O 2, gives the sour taste to vinegar. Calculate the moles of acetic acid present in a 25.8 g sample. Step 4 Set up the problem to convert grams to moles. Solution

27. © 2013 Pearson Education, Inc. Chapter 6, Section 5 27 Connections between Mass, Moles, and Particles

28. © 2013 Pearson Education, Inc. Chapter 6, Section 5 28 Calcium carbonate, CaCO 3 is found in antacid tablets. If we have a 0.320 mole sample of CaCO 3, how many grams are present? Learning Check

29. © 2013 Pearson Education, Inc. Chapter 6, Section 5 29 Calcium carbonate, CaCO 3 is found in antacid tablets. If we have a 0.320 mole sample of CaCO 3, how many grams are present? Step 1 State the given and needed quantities. Analyze the Problem Step 2 Write a plan to convert grams to moles. moles of CaCO 3 molar mass grams of CaCO 3 Solution GivenNeed 0.320 mole CaCO 3 grams of CaCO 3

30. © 2013 Pearson Education, Inc. Chapter 6, Section 5 30 Calcium carbonate, CaCO 3 is found in antacid tablets. If we have a 0.320 mole sample of CaCO 3, how many grams are present? Step 3 Determine the molar mass and write conversion factors. 1 mole of CaCO 3 = 100.1 g of CaCO 3 Solution

31. © 2013 Pearson Education, Inc. Chapter 6, Section 5 31 Calcium carbonate, CaCO 3 is found in antacid tablets. If we have a 0.320 mole sample of CaCO 3, how many grams are present? Step 4 Set up the problem to convert moles to grams. Solution