 # 1 The Mole 6.02 X 10 23 2 AVOGADRO’S NUMBER AND MOLAR CONVERSIONS TEXTBOOK PAGE 224 READ P 224 TO 228 DO PRACTICE QUESTIONS 1 TO 4 PAGE 228.

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1 The Mole 6.02 X 10 23

2 AVOGADRO’S NUMBER AND MOLAR CONVERSIONS TEXTBOOK PAGE 224 READ P 224 TO 228 DO PRACTICE QUESTIONS 1 TO 4 PAGE 228

3 The Mole A counting unit Similar to a dozen, except instead of 12, is 602,000,000,000,000,000,000,000 6.02 X 10 23 (in scientific notation) Amedeo AVOGADRO (1776 – 1856)This number is named in honor of Amedeo AVOGADRO (1776 – 1856), who studied quantities of gases and discovered that no matter what the gas was, there were the same number of molecules present

4 Just How Big is a Mole? Enough soft drink cans to cover the surface of the earth to a depth of over 200 miles. If you had Avogadro's number of unpopped popcorn kernels, and spread them across the United States of America, the country would be covered in popcorn to a depth of over 9 miles. If we were able to count atoms at the rate of 10 million per second, it would take about 2 billion years to count the atoms in one mole.

5 The Mole 1 dozen cookies = 12 cookies 1 mole of cookies = 6.02 X 10 23 cookies 1 dozen cars = 12 cars 1 mole of cars = 6.02 X 10 23 cars 1 dozen Al atoms = 12 Al atoms 1 mole of Al atoms = 6.02 X 10 23 atoms Note that the NUMBER is always the same, but the MASS is very different! Mole is abbreviated mol (gee, that’s a lot quicker to write, huh?)

6 = 6.02 x 10 23 C atoms = 6.02 x 10 23 H 2 O molecules = 6.02 x 10 23 NaCl “molecules” (technically, ionics are compounds not molecules so they are called formula units) 6.02 x 10 23 Na + ions and 6.02 x 10 23 Cl – ions A Mole of Particles A Mole of Particles Contains 6.02 x 10 23 particles 1 mole C 1 mole H 2 O 1 mole NaCl

7 6.02 x 10 23 particles 1 mole or 1 mole 6.02 x 10 23 particles Note that a particle could be an atom OR a molecule! Avogadro’s Number as Conversion Factor

8 1. Number of atoms in 0.500 mole of Al a) 500 Al atoms b) 6.02 x 10 23 Al atoms c) 3.01 x 10 23 Al atoms 2.Number of moles of S in 1.8 x 10 24 S atoms a) 1.0 mole S atoms b) 3.0 mole S atoms c) 1.1 x 10 48 mole S atoms Learning Check

9 The Mass of 1 mole (in grams) Equal to the numerical value of the average atomic mass (get from periodic table) 1 mole of C atoms= 12.0 g 1 mole of Mg atoms =24.3 g 1 mole of Cu atoms =63.5 g Molar Mass

10 Other Names Related to Molar Mass Molecular Mass/Molecular Weight: If you have a single molecule, mass is measured in amu’s instead of grams. But, the molecular mass/weight is the same numerical value as 1 mole of molecules. Only the units are different. (This is the beauty of Avogadro’s Number!) Formula Mass/Formula Weight: Same goes for compounds. But again, the numerical value is the same. Only the units are different. THE POINT: You may hear all of these terms which mean the SAME NUMBER… just different units

11 Find the molar mass ( round to no decimals) Learning Check! A.1 mole of Br atoms B.1 mole of Sn atoms =80 g/mole = 119 g/mole

12 Mass in grams of 1 mole equal numerically to the sum of the atomic masses 1 mole of CaCl 2 = 111 g/mol 1 mole Ca x 40 g/mol + 2 moles Cl x 35.5 g/mol = 111 g/mol CaCl 2 1 mole of N 2 O 4 = 92 g/mol Molar Mass of Molecules and Compounds

13 A.Molar Mass of K 2 O = ? Grams/mole B. Molar Mass of antacid Al(OH) 3 = ? Grams/mole Learning Check!

14 Prozac, C 17 H 18 F 3 NO, is a widely used antidepressant that inhibits the uptake of serotonin by the brain. Find its molar mass. Learning Check

15 molar mass Grams Moles Calculations with Molar Mass

16 Aluminum is often used for the structure of light-weight bicycle frames. How many grams of Al are in 3.00 moles of Al? 3.00 moles Al ? g Al Converting Moles and Grams

17 1. Molar mass of Al1 mole Al = 27.0 g Al 2. Conversion factors for Al 27.0g Al or 1 mol Al 1 mol Al 27.0 g Al 3. Setup3.00 moles Al x 27.0 g Al 1 mole Al Answer = 81.0 g Al

18 The artificial sweetener aspartame (Nutra-Sweet) formula 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!

19 Atoms/Molecules and Grams Since 6.02 X 10 23 particles = 1 mole AND 1 mole = molar mass (grams) You can convert atoms/molecules to moles and then moles to grams! (Two step process) You can’t go directly from atoms to grams!!!! You MUST go thru MOLES. That’s like asking 2 dozen cookies weigh how many ounces if 1 cookie weighs 4 oz? You have to convert to dozen first!

20 molar mass Avogadro’s number Grams Moles particles Everything must go through Moles!!! Calculations

21 Atoms/Molecules and Grams How many atoms of Cu are present in 35.4 g of Cu? 35.4 g Cu 1 mol Cu 6.02 X 10 23 atoms Cu 63.5 g Cu 1 mol Cu = 3.4 X 10 23 atoms Cu

22 Learning Check! How many atoms of K are present in 78.4 g of K?

23 Learning Check! What is the mass (in grams) of 1.20 X 10 24 molecules of glucose (C 6 H 12 O 6 )?

24 Learning Check! How many atoms of O are present in 78.1 g of oxygen? 78.1 g O 2 1 mol O 2 6.02 X 10 23 molecules O 2 2 atoms O 32.0 g O 2 1 mol O 2 1 molecule O 2

25 APRIL 11 WHAT IS THE VOLUME OF A MOLE?

26 DO NOW Find the mass of the following A) 1 mol of Ar (g) B) 1 mol of N 2 (g) C) 1 mol of CO 2 (g)

27 MOLAR VOLUME The volume of a mole of any gas at STP is 22.4 liters.

28 Avogadro’s hypothesis Equal volumes of any gas at the same temperature an pressure contains the same number of molecules.

29 April 12 Stoichiometry problems HOMEWORK Study page 302-305 in texbook Do practice questions 1 and 2 from page 304

30 Answers to Molar Volume Practice 1)C 2)A 3)D 4)B 5)D 6)C 7)A 8)C 9)A 10)C 11)B 12)B 13)D 14)B 15)C 16)B 17)D

31 Set 1 – Mole calculations 1.3 2.4 3.2 4.2 5.2 6. 0.50 mol 7. 781 g 8. 8.40 g/ 58g/mol 9)3 10)2 11)1 12)4 13)1 14)4 15)1 16)11g/ 44g/mol 17) 0.8 mol

32 APRIL 15 Objective: How to work with stoichiometric relationships? MOL TO MOL PROBLEMS Do now Write the equation for formation of Aluminum Oxide and balance it

33 STOICHIOMETRYSTOICHIOMETRY - the study of the quantitative aspects of chemical reactions.

34 Challenge How many mol of O 2 are needed to produce 3 mol of Aluminum Oxide? How many mol of Aluminum are needed?

35 Page 228 1. 1.13 x 10 23 ions of Na + 8.73 x 10 6 atoms of As 2.54 x 10 24 molecules 3.6 x 10 24 formula units

36 Mass to mol problems How many mol of water can be produced if 6 g of H2 react with an excess of O2 ? HINT CONVERT THE GIVEN AMOUNT TO MOL!!!!! Given Unknown

37 How many mol of C are needed to produce 88g of CO2? Convert given to mol!!!! Given Unknown

38 APRIL 16 Objective: To practice mol to mol problems and to review for tomorrow’s test DO NOW : Read ‘Mathematics of chemistry part 2 – Stoichiometry’ and DO PROBLEMS 1 TO 8

39 TOPICS FOR TOMORROW’S TEST % Composition – hydrates Balancing chemical equations Recognize types of chemical reactions Mole conversions Mol to mol problems

40 EXIT SLIP How many mol of O2 are needed to produce 12 mol of H2O ? 4NH3+5O2  4 NO + 6 H2O

41 STOICHIOMETRY (mol problems) 1- 5 mol H2 2- 1 mol F2O3 3- 3 mol FeCl3 4- 3.75 mol O2 5- 0.6 mol N2 6- 3.8 mol H2 7- 0.25 mol H2 8- 1.6 mol Zn

42 STOICHIOMETRIC RELATIONSHIP 1 4.5 mol O2 2 0.2 mol Zn 3 8 mol O2 4 6 mol H2 5 12 mol NH3 6 3 mol S 7 2 mol AgCl

43 REVIEW SHEET ANSWERS 1.A 2.C 3.D 4.D 5.C 6.B 7.B 8.A 9.C 10.B 20. 4 11.C 21. 4 12.B 22. 4 13.D 23. 3 14.B 15.A 17. D 18.4 19.1

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