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Friday, March 21 st : “A” Day Monday, March 24 th : “B” Day Agenda

Friday, March 21 st : “A” Day Monday, March 24 th : “B” Day Agenda. Homework Questions/Collect Finish section 7.1…finally! In-class: Practice pg. 231: #1-4 Practice pg. 232: #1-3 Homework: Practice worksheet pg 24/25 Must SHOW WORK for credit!.

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Friday, March 21 st : “A” Day Monday, March 24 th : “B” Day Agenda

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  1. Friday, March 21st: “A” DayMonday, March 24th: “B” DayAgenda • Homework Questions/Collect • Finish section 7.1…finally! • In-class: • Practice pg. 231: #1-4 • Practice pg. 232: #1-3 • Homework: • Practice worksheet pg 24/25 • Must SHOW WORK for credit!

  2. Homework“Grams/Moles Calculations” worksheet • Questions/Problems? • Hand in

  3. Changing Particles Mass • Now that you know how to change particles into moles and moles into mass (in grams), we can put these two steps together to convert from Particles Mass!

  4. Changing Particles Mass • You need 2 steps to change number of particles to mass, in grams: 1. Change particles to moles using Avogadro’s number 2. Change moles to mass using the molar mass • Two different conversion factors must be used!

  5. Particles Mass Sample Problem C, pg. 231 • Find the mass in grams of 2.44 X 1024 atoms of carbon, whose molar mass is 12.01 g/mol. • Start with what you know: 2.44 X 1024 atoms C • Use Avogadro’s number as a conversion factor to change atoms C moles C: • 2.44 X 1024 atoms C X 1 mol C 6.022 X 1023 atoms C = 4.05 mol C

  6. Particles Mass Sample Problem C, pg. 231, cont. 3. Now, use molar mass of carbon to change moles C mass (in grams) of C: • 4.05 moles C X 12.01 g C 1 mole C 48.6 g C (3 sig figs)

  7. Particles Mass Practice #1 • Find the mass in grams of 6.12 X 1014 formula units of rhenium dioxide, ReO2, 218.21 g/mol. • Start with what you know: 6.12 X 1014 form. units ReO2 • Use Avogadro’s number as a conversion factor to change form. units ReO2 moles ReO2: • 6.12 X 1014 form. units X 1 mol ReO2 6.022 X 1023 form. units = 1.02 X 10-9 mole ReO2

  8. Particles Mass Practice #1, cont. 3. Now, use molar mass of ReO2 to change moles ReO2 mass (in grams) of ReO2: • 1.02 X 10-9 mole ReO2 X 218.21 g ReO2 1 mole ReO2 2.23 X 10-7 g ReO2 (3 sig figs)

  9. Changing Mass Particles • Converting from mass to number of particles is simply the opposite of what you’ve just done. • You need 2 steps to change number of particles to mass: • Change mass to moles using molar mass • Second, change moles to particles using Avogadro’s number • Two different conversion factors must be used!

  10. Mass Particles Sample Problem D, pg. 232 • Find the number of molecules present in 47.5 g of glycerol, C3H8O3. The molar mass of glycerol is 92.11 g/mol. • Start with what you know: 47.5 g C3H8O3 2. Use molar mass of C3H8O3 to change mass C3H8O3 moles C3H8O3: 47.5 g C3H8O3 X 1 mol C3H8O3 = .516 mol C3H8O3 92.11 g C3H8O3

  11. Mass Particles Sample Problem D, cont. • Now, use Avogadro’s number to change moles molecules: • 0.516 mol C3H8O3 X 6.022 X 1023 molecules C3H8O3 1 mole C3H8O3 3.11 X 1023 moleculesC3H8O3 (3 sig figs)

  12. Mass Particles Additional Practice • Determine the number of atoms present in 54.3 grams of cobalt, Co. 1. Start with what you know: 54.3 g Co • Use molar mass of Co to change mass Co mole Co: • 54.3 g Co X 1 mol Co= .921 mole Co 58.93 g Co

  13. Mass Particles Additional Practice, cont. • Now, use Avogadro’s number to change moles Co atoms Co: • 0.921 moles Co X 6.022 X 1023 atoms Co 1 mole Co 5.55 X 1023 atoms Co

  14. In-Class Assignments/HomeworkYou Must SHOW WORK! • Practice pg. 231: #1-4 • Practice pg. 232: #1-3 • Practice worksheet, pg. 24/25 • Concept Review: • “Avogadro’s Number & Molar Conversions”

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