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Today is Friday (!), April 4 th , 2014

Stuff You Need : Calculator Periodic Table. In This Lesson: Unit 4 Moles and Mole Conversions (Lesson 1 of 4). Today is Friday (!), April 4 th , 2014. Pre-Class:

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Today is Friday (!), April 4 th , 2014

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  1. Stuff You Need: • Calculator • Periodic Table In This Lesson: Unit 4 Moles and Mole Conversions (Lesson 1 of 4) Today is Friday (!),April 4th, 2014 Pre-Class: Take a look at the graduated cylinder near the projector. There are 18 mL of water in it. If you had to guess, about how many water molecules are in there? Also: You need your periodic table and calculator.

  2. Today’s Agenda • The Mole! • Working with Moles • Where is this in my book? • P. 287 and following…

  3. By the end of this lesson… • You should be able to calculate the number of moles in a quantity of a substance.

  4. The Mole • 1 dozen of something equals how many? • 12 • 1 mole of something equals how many? • 6.02 x 1023 (or 602,000,000,000,000,000,000,000) • For chemistry, a mole of a substance equals 6.02 x 1023representative particles. • 1 mole of iron = 6.02 x 1023 iron atoms. • 1 mole of carbon dioxide = 6.02 x 1023 carbon dioxide molecules. • 1 mole of sodium chloride = 6.02 x 1023 sodium chloride formula units.

  5. Did you get that? • The smallest unit of a(n) ____ is a(n) ____: • element…atom • covalent compound…molecule • ionic compound…formula unit

  6. Avogadro’s Number • 6.02 x 1023 is called “Avogadro’s Number” in honor of the Italian chemist Amadeo Avogadro (1776-1855). • He did not actually discover the number, however. • Fun fact: Avogadro’s full name was Lorenzo Romano Amadeo Carlo Avogadro, Count of Quarequa and Cerreto. Amadeo Avogadro

  7. Avogadro’s Number

  8. Quick Mole Questions • 1 Dozen Cars • 1 Dozen Tricycles • Of which vehicle do I have more? • I have the same amount of each vehicle. • 1 Mole of Molecule A = C2H6 • 1 Mole of Molecule B = C8H8 • Of which molecule do I have more? • I have the same amount of each molecule!

  9. Quick Mole Questions • 1 Dozen Cars • 1 Dozen Tricycles • Do I have more car wheels or tricycle wheels? • More car wheels (each car has 4, each tricycle has 3). • 1 Mole of Molecule A = C2H6 • 1 Mole of Molecule B = C8H8 • Do I have more atoms from Molecule A or Molecule B? • More atoms from Molecule B (each B molecule has 16 atoms, each A molecule has 8 atoms).

  10. How big is a mole? • Video!

  11. Molar Mass • Molar mass (also known as formula mass) is the total atomic mass of a compound or element. • In other words, just add all the atomic masses of the elements in a compound together. • Molar mass equals the mass in grams of one mole of a substance. • One mole of hydrogen (H) has a mass of ~1.0079 g. • One mole of hydrogen gas (H2) has a mass of ~2.016 g. • Molar mass is measured in grams per mole or g/mol.

  12. Moles and Gases • For solids and liquids, the molar mass of a substance equals one mole. • For gases, 22.4 Liters (L) = 1 mole. • This works for any gas at STP (standard temperature and pressure). • This is called the molar volume. • Like the molar mass, only…you know…volume.

  13. So… Molar Mass 1 Mole 22.4 Liters (Gas) 6.02 x 1023 rep. part

  14. Molar Mass Practice • Calculate the molar mass of carbon dioxide. • Formula of carbon dioxide = CO2. • Carbon mass = 12.0107 g/mol. • Oxygen mass = 15.9994 g/mol. • 12.0107 + 15.9994 * 2 = 44.0095 g/mol. • So, one mole of CO2, or 6.02 x 1023 molecules, has a mass of about 44 grams.

  15. Hydrates • While we’re on the topic of formula mass, we should talk about hydrates. • Hydrates are substances, typically salts, that contain water within their chemical bonds. • Because of this, their formulas include H2O. • Example: CoCl2 • 6H2O • This is cobalt (II) chloride with six attached water molecules.

  16. Naming Hydrates • CoCl2 • 6H2O is “Cobalt II chloride hexahydrate.” • CoCl2 • 5H2O is “Cobalt II chloride pentahydrate.” • I think you get the idea. • CoCl2 is “Cobalt II chloride anhydrous,” which just means it is not hydrated.

  17. Hydrates

  18. Hydrate Molar Mass • We’ll look more at hydrates when we do our Formula of a Hydrate lab. For now, know this: • To calculate molar mass of a hydrate, add the mass of water (times the coefficient) to the rest of the formula’s mass. • Example: CoCl2 • 6H2O • Add up Co’s mass, Cl’s mass (times two) and water’s mass (times six). • 58.93 + 35.45 * 2 + 18.0148 * 6 = 237.9188 g/mol. • The • looks like a multiplication symbol, but don’t do that. That’d be bad.

  19. Molar Mass Worksheet • Let’s try a QUICK worksheet (Molar Mass) that will help you practice molar/formula mass. • Try 1/4 the problems. Any 10, as long as you do 10. • You must try at least one of 30, 39, or 40, and at least one of your ten has to have parentheses. • ( ) around something means the subscript outside them is distributive – you’ll need to do a little multiplication for those. • Example: Al2(SO4)3– calculate SO4’s molar mass and multiply by 3. • Similar to what is done for hydrates.

  20. Mole Calculations • Now that you know how to find the mass of a mole of something, it’s time to learn how to do some calculations relating to that. • The good news is we’re still going to be using our old friend from unit analysis: • The other good news is that I have a system for you to learn how to make these calculations. • It’s called the mole highway.

  21. The Mole Highway 6.02x1023 Rep. Part. 1 mol 1 mol Molar Mass 1 mol 22.4 L x x x x x x 1 mol Molar Mass 1 mol 22.4 L 1 mol 6.02x1023 Rep. Part. Atoms, Molecules, or Formula Units Mass (g) Volume (L)

  22. The Mole Highway 6.02x1023 Rep. Part. 6.02x1023 Rep. Part. x Molar Mass ÷ Molar Mass x 22.4 L ÷ 22.4 L x ÷ Atoms, Molecules, or Formula Units Mass (g) Volume (L)

  23. Mole Conversion Triforce g L rep. part. mol mol mol molar mass 6.02x 1023 22.4

  24. Mole Calculations How many grams of lithium are in 3.50 moles of lithium? There are 24.3 g of lithium in 3.50 mol.

  25. Mole Calculations How many moles of lithium are in 18.2 grams of lithium? There are 2.62 mol of lithium in 18.2 g.

  26. Mole Calculations How many atoms of lithium are in 3.50 moles of lithium? There are 2.11 x 1024 atoms of lithium in 3.50 mol.

  27. The Big Idea • As your Mole Highway shows: • Moles  Grams = Multiply • (MGM) • Grams  Moles = Divide

  28. Moles to Grams

  29. Grams to Moles

  30. Let’s Talk About Gas • You may have noticed another set of lanes on the mole highway for volume. • When it comes to gases, we can also determine the volume a mole of a gas will take up (like we can determine the mass of a mole of something). • One mole of any gas takes up 22.4 L at standard temperature and pressure. • Molar mass doesn’t have anything to do with this. • Conversions work the same way.

  31. Mole Calculations How many liters do 2.00 moles of hydrogen gas occupy at standard temperature and pressure? 2.00 moles of H2 take up 44.8 L.

  32. Mole Calculations How many moles are in 14.2 liters of argon gas at standard temperature and pressure? 14.2 L of Ar is 0.634 mol.

  33. The Big Idea • As your Mole Highway shows: • Moles  Liters = Multiply • Liters  Moles = Divide

  34. Moles to Liters…and vice versa…

  35. Mole Calculations How many atoms are in fifteen moles of lead? In 15 moles of Pb, there are 9.0 x 1024 atoms.

  36. Mole Calculations How many moles are in 5.2 x 1024 molecules of F2? If you have 5.2 x 1024 molecules of F2, you have 8.6 moles.

  37. The Big Idea • As your Mole Highway shows: • Moles  Representative Particles = Multiply • Representative Particles  Moles = Divide

  38. Moles to Representative Particles…and vice versa…

  39. Practice • Mole Calculation Practice Worksheet • #1-4 • Mole Conversions Worksheet • #1-6 [4 is a challenge]

  40. Two Step Mole Conversions • Sometimes you’ll need to go from grams to liters or atoms to grams. • In these cases, you’ll still use the mole highway, but you’ll have to use it for two steps. • For example, let’s look at the path you’d take if you needed to go from grams to atoms.

  41. The Mole Highway 6.02x1023 Rep. Part. 1 mol 1 mol Molar Mass 1 mol 22.4 L x x x x x x 1 mol Molar Mass 1 mol 22.4 L 1 mol 6.02x1023 Rep. Part. Atoms, Molecules, or Formula Units Mass (g) Volume (L)

  42. Mole Calculations How many atoms of lithium are in 18.2 grams of lithium? There are 1.58 x 1024 atoms of lithium in 18.2 g.

  43. Mole Calculations How many formula units of sodium chloride are in 14.0 grams of sodium chloride? There are 1.44 x 1023 units of NaCl in 14.0 g.

  44. Mole Calculations How many grams of water are in 1.204 x 1024 molecules of water? 1.204 x 1024 molecules of water weigh 36.03 g.

  45. Moles/Grams to Liters(and vice versa)

  46. Practice • Mole Conversions worksheet • #7-12 • Mole Calculation Practice Worksheet • #5-6

  47. Closure • Quick interesting note: • For some reason, it seems like every two-step mole conversion requires you to first divide, then multiply. • Multiply or divide by what? You decide. • Example: Grams to Liters: • Divide by molar mass, multiply by 22.4.

  48. Closure • How many representative particles are in 71.91 grams of diatomic bromine? • Br2 formula mass = 159.81 g/mol • 71.91 g / 159.81 g/mol = 0.45 moles • 0.45 moles x 6.02 x 1023 = 2.709 x 1023 particles.

  49. Mole Conversions Boss • Automobiles in the US emit approximately 1.5 billion metric tons of carbon dioxide annually. How many liters is this at STP? • 1 metric ton = 2204.6 pounds • 2.2 pounds = 1 kilogram = 7.7 x 1014 L 1.5x109 t 2204.6 lbs 1 kg 1000 g 1 mol 22.4 L 1 t 2.2 lbs 1 kg 44.009 g 1 mol https://www.fueleconomy.gov/feg/climate.shtml http://img1.wikia.nocookie.net/__cb20110523221131/villains/images/6/66/Bowser_SMG.jpg

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