1. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Dalton Pre-lab Write out procedure using pictures & descriptions Safety Precautions Example: NEVER TOUCH CRUCIBLE Prepare 3 data tables If this is NOT complete by the beginning of class tomorrow you will need to make up the lab on Thursday After School & you will get a ZERO for the pre-lab. 1

2. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 2 3.3 Counting Atoms

3. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 3 The molar mass is  the mass of one mole of a substance  the atomic mass of an element expressed in grams Molar Mass

4. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 4 What is a mole? https://www.youtube.com/watch?v=TEl4jeETVmg

5. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 5 Give the molar mass to the nearest 0.1 g. A. K = ________ B. Sn = ________ Learning Check

6. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 6 Give the molar mass to the nearest 0.1 g. A. K =39.1 g B. Sn =118.7 g Solution

7. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 7 Molar Mass of CaCl 2  For a compound, the molar mass is the sum of the molar masses of the elements in the formula. We calculate the molar mass of CaCl 2 to the nearest 0.1 g as follows. ElementNumber of Moles Atomic MassTotal Mass Ca140.1 g/mole 40.1 g Cl235.5 g/mole 71.0 g CaCl 2 1 111.1 g

8. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 8 Molar Mass of K 3 PO 4 Determine the molar mass of K 3 PO 4 to 0.1 g. ElementNumber of Moles Atomic MassTotal Mass in K 3 PO 4 K339.1 g/mole 117.3 g P131.0 g/mole 31.0 g O416.0 g/mole 64.0 g K 3 PO 4 1 212.3 g

9. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Guide to Calculating Molar Mass Find the molar mass of each element Multiply the molar mass by the number of moles (subscript) for each element in the compound Calculate molar mass by adding up the mass of each element in the compound 9

10. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 10 Calculate the molar mass for Al(OH) 3 to the nearest 0.1g. 1) 44.0 g/mole 2) 75.0 g/mole 3) 78.0 g/mole Learning Check

11. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 11 STEP 1 Obtain the molar mass of each element. Al 27.0 g/mole O 16.0 g/mole H 1.0 g/mole STEP 2 Multiply each by the subscript in the formula. 1 mole Al x 27.0 g Al = 27.0 g 1 mole Al 3 moles O x 16.0 g O = 48.0 g 1 mole O 3 moles H x 1.0 g H = 3.0 g 1 mole H STEP 3 Total: 1 mole of Al(OH) 3 = 78.0 g (3) Solution

12. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 12 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. 16.0 g CH 4 and 1 mole CH 4 1 mole CH 4 16.0 g CH 4 Conversion Factors from Molar Mass

13. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 13 Acetic acid, C 2 H 4 O 2, gives the sour taste to vinegar. Write an equality and two molar mass conversion factors for acetic acid. Learning Check

14. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 14 Acetic acid, C 2 H 4 O 2, gives the sour taste to vinegar. Write an equality and two molar mass conversion factors for acetic acid. Equality: 1 mole of acetic acid = 60.0 g of acetic acid Molar mass conversion factors: 1 mole acetic acid and 60.0 g acetic acid 60.0 g acetic acid 1 mole acetic acid Solution

15. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 15 Guide to Calculations Using Molar Mass

16. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 16 Aluminum is often used for the structure of lightweight bicycle frames. How many grams of Al are in 3.00 moles of Al? 3.00 moles Al x 27.0 g Al = 81.0 g of Al 1 mole Al mole factor for Al Calculating Grams from Moles

17. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 17 The artificial sweetener aspartame (NutraSweet), C 14 H 18 N 2 O 5, is used to sweeten diet foods, coffee, and soft drinks. How many moles of aspartame are present in 225 g of aspartame? Learning Check

18. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 18 STEP 1 Given: 225 g of aspartame, C 14 H 18 N 2 O 5 STEP 2 Plan: g of aspartame moles of aspartame STEP 3 Determine molar mass of aspartame: 14(12.0) + 18(1.0) + 2(14.0) + 5(16.0) = 294 g/mole STEP 4 Set up problem to calculate the moles of aspartame: 225 g aspartame x 1 mole aspartame 294 g aspartame mole factor (inverted) = 0.765 mole of aspartame Solution

19. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Avogadro’s Number 6.02 x 10 23 atoms = 1 mole 19

20. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Calculations using Avogadro’s Number 1. Determine the given number of moles or atoms 2. Use the conversion factor for atoms to moles 3. Solve 20

21. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Learning Check How many atoms are in 2.0 moles of carbon? 21

22. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Converting Between Mass, Moles, and Particles 22