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OB: Intro to the Mole

OB: Intro to the Mole. You gotta have a reference table and a calculator of your own now. No exceptions. One way to measure how much someone loves you is to see if they know that a dozen roses means twelve. * ( * not really, it’s a silly comparison).

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OB: Intro to the Mole

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  1. OB: Intro to the Mole You gotta have a reference table and a calculator of your own now. No exceptions.

  2. One way to measure how much someone loves you is to see if they know that a dozen roses means twelve.* (*not really, it’s asilly comparison) A deck of cards means 52 cards. 51 is not good. And we know shoes come in pairs of 2.

  3. You could have a pair of atoms, or a dozen, or even 52, but you wouldn’t know it because atoms are so small. We need a bigger unit, and that’s what a mole is. A mole is a certain number of particles. You could have a mole of: atoms molecules cations or anions formula units (!) these are the smallest mathematical part of an ionic compound since “molecules” of a salt do not exist naturally ever. A mole is 6.02 x 1023 of something. That is: 602,000,000,000,000,000,000,000 of them. That is a really, really big number.

  4. No one ever counted that many, it’s been worked out mathematically and is called: Avogadro’s Number 6.02 x 1023 in honor of Amedo Avogadro, an Italian chemist who studied gases. So, how many atoms are in one mole of mercury? That would be 6.02 x 1023 atoms of mercury. How many atoms are in one half mole of carbon?That’s just 3.01 x 1023 atoms of carbon. half

  5. Get ready... What is the mass of one mole of mercury? One atom of Hg has a weighted average mass of 200.59 amu In our class we’d round that to the nearest whole number, so 201 amu is the mass of one atom of mercury. 6.02 x 1023 atoms of mercury has mass of 201 grams. Did you catch that conversion factor?

  6. Determine the mass of… 1.0 mole of carbon 2.0 moles of aluminum 3.0 moles of helium 0.50 moles magnesium This one will be tricky, tricky, tricky… What is the mass of one mole of oxygen gas?

  7. Determine the mass of… 1.0 mole of carbon = 12 grams 2.0 moles of aluminum 3.0 moles of helium 0.50 moles magnesium This one will be tricky, tricky, tricky… What is the mass of one mole of oxygen gas?

  8. Determine the mass of… 1.0 mole of carbon = 12 grams 2.0 moles of aluminum = 2 x 27 g = 54 grams 3.0 moles of helium 0.50 moles magnesium This one will be tricky, tricky, tricky… What is the mass of one mole of oxygen gas?

  9. Determine the mass of… 1.0 mole of carbon = 12 grams 2.0 moles of aluminum = 2.0 x 27 g = 54 grams 3.0 moles of helium = 3.0 x 4 = 12 grams 0.50 moles magnesium This one will be tricky, tricky, tricky… What is the mass of one mole of oxygen gas?

  10. Determine the mass of… 1.0 mole of carbon = 12 grams 2.0 moles of aluminum = 2.0 x 27 g = 54 grams 3.0 moles of helium = 3.0 x 4 = 12 grams 0.50 moles magnesium = 0.50 x 24 g = 12 grams This one will be tricky, tricky, tricky… What is the mass of one mole of oxygen gas?

  11. Determine the mass of… 1.0 mole of carbon = 12 grams 2.0 moles of aluminum = 2.0 x 27 g = 54 grams 3.0 moles of helium = 3.0 x 4 = 12 grams 0.50 moles magnesium = 0.50 x 24 g = 12 grams This one will be tricky, tricky, tricky… What is the mass of one mole of oxygen gas? Oxygen is O2, it’s diatomic, so 2 x 16g = 32 grams The HONClBrIF twins can be fun or tormenting!

  12. What is the mass of one mole of magnesium oxide? (wow, this is a great question! I could also have asked, what is the molar mass of magnesium oxide? One mole of a substance is equal to it’s molar mass. That’s vocabulary. To do this, write the formula, underline it, and list the atoms in the compound like this: MgO Mg O

  13. MgO Mg = 1 mole x 24 g/mole = 24 g O = 1 mole x 16 g/mole = 16 g 1 mole of MgO = 40 g You can say it this way: MgO has a molar mass of 40 grams per mole, Or There are 40 grams of magnesium oxide in one mole of MgO.

  14. Determine the molar mass of carbon dioxide CO2 C O

  15. Determine the molar mass of carbon dioxide CO2 C 1 x 12 g = 12 g O 2 x 16 g = 32 g CO2 is 44g/mole

  16. What is the mass of 2.5 moles of sulfur? To do these problems we need first to determine the molar mass for the element… The molar mass of sulfur is: ________________________ Which means, one mole sulfur = _______ grams of sulfur (that is a conversion factor begging to be used!)

  17. The molar mass of sulfur is 32g/mole. To do this math problem: 2.5 moles S 1 x 32 g Sulfur1 mole sulfur = 80. g Sulfur Starting point of problem over one Conversion factor from periodic table with unlimited SF Correct answer with proper number of SF In every box on the periodic table is a conversion factor waiting for you. One mole of atoms of any element is equal to the molar mass (with unlimited SF)

  18. What is the mass of 0.356 moles of lead? First determine the molar mass of lead and write it down neatly. Then, start the problem in the right place, put it “over one”. (it’s always best to start at the beginning). Then, neatly write out the math, use your calculators, get it right the first time. What’s her name? She’s one of my heroes!

  19. 73.692 grams 73.7 g Pb with 3SF 207 g lead1 mole Pb 0.356 moles lead1 x = It is way cool that you can do this now… Try one more: What is the mass of 1.45 moles of boron? Boron has a molar mass of 11g/mole That number has unlimited SF, since one mole boron = 11 grams of boron

  20. 1.45 mole B1 11 g B1 mole B X = 15.95 g B 16.0 g B with 3 SF Tonight’s Homework Play whack a mole in your head. Do the second set of drills for molecular compounds. Do them, no kidding. Finish up the Naming Compounds Diary. Really. There are lots of important dates coming up, like the 1st Quarter Unit Celebration of Knowledge taken IN CLASS, check the homepage.

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