Celebrate MOLE Day! October 23 rd from 6:02 a.m. till 6:02 p.m. IV. Relating Mass to Numbers of Atoms.
1. The Mole (can be abbreviated mol, but NOT m, which is the abbreviation for meter!) - the SI unit for amount of substance. A mole is the amount of a substance that contains as many particles as there are atoms in exactly 12 grams of carbon-12.
-the number of particles in exactly one mole of a pure substance. This number was determined experimentally and its value is 6.022 X 1023, which means that 12 g of carbon-12 contains 6.022 x 1023 carbon-12 atoms.
OK, so How many is a mole? How large is Avogrado’s number…
Let’s get some perspective…
If every person living on Earth (6 billion people) worked to count out one mole of oranges (or anything else), and if each person counted continually at a rate of one orange per second, it would take about 4 million years for all the oranges to be counted!
If we had a mole of sand it would cover the earth 7 times over! If you had a mole of dollar bills, you could spend a million dollars every minute of your life and never spend it all!!!
3. Molar Mass for compounds
How to find the molar mass:
Example: find the molar mass of NaCl.
Example: find the molar mass of calcium phosphate, Ca3(PO4)2.
1 mole = 6.022X1023 atoms OR molecules OR formula units
1 mole Al = 26.98 grams
1 atom Al = 26.98 amu
1. Gram/Mole conversions-how to convert moles to grams or grams to moles.
Example: 120 g Ca x 1 mole Ca = 2.99 mole Ca
40.1 g Ca
2. Conversions with Avogadro’s Number
Example: How many atoms of silver, Ag, are in 4.25 moles of Ag?
4.25 moles Ag X 6.022 x 1023 atoms Ag =
1 mole Ag
Ex: How many atoms of sodium, Na, are in 5.25 g of Na?
5.25 g Na x 1 mole Na x 6.022 x 1023 atoms Na =
23 g Na 1 mole Na
Practice: What is the formula mass of barium chloride dehydrate, BaCl2 · 2H2O?
What is the formula mass of aluminum sulfate octahydrate, Al2(SO4)3 · 8H2O?