1. Ways We Measure You can measure mass, or volume, or you can count pieces. We measure mass in grams. We measure volume in liters. We count pieces in MOLES.

2. What is a mole? A counting number (like a dozen) A quantity = to Avogadro’s number 1 mol = 6.02 x 10 23 items A large amount!!!! 1 mol = 602,000,000,000,000,000,000,000

3.  1 mole of hockey pucks would equal the mass of the moon!  1 mole of pennies would cover the Earth 1/4 mile deep!  1 mole of basketballs would fill a bag the size of the earth!

4. Representative particles Representative particles are the smallest pieces of a substance. –For a molecular compound: it is the molecule. –For an ionic compound: it is the formula unit. –For an element: it is the atom. Remember the 7 diatomic elements (made of molecules) –Br 2, I 2, N 2, Cl 2, H 2, O 2, F 2,

5. 6.02 x 10 23 Particles=1 mol MOLES NUMBER OF PARTICLES Particles = Molecules Formula units Atoms

6. Chemical Quantities 1. Use dimensional analysis: What is the mass of 90 average sized apples if 1 dozen of the apples has a mass of 2.0 kg? 2. Count and compare tiny objects: How many pieces of sand are in the beaker? Many of the items contained in this presentation contain materials created by others. Moles help us because atoms are so tiny and in the lab we can’t count directly the number of atoms so we use moles to compare…how?

7. Converting Number of Particles to Moles 1 mol = 6.02 x 10 23 representative particles 1 mol 6.02 x 10 23 rep.part. OR 1 mol

8. Converting Number of Particles to Moles 3a. Calculate the number of moles for 6.022 X 10 24 atoms of cobalt. Answer: 10.00 moles 6.022 X 10 24 atoms Co X 1 mol Co = 6.02 X 10 23 atoms Co 6.02 X 10 23 atoms Co What will the conversion factor look like if the problem asked for how many atoms are in 6.02 moles? 6.02 X 10 23 atoms 1 mol

9. Molar Mass Mass of 1 mole of an element or compound. # of grams per mole (g/mol) Round to 2 decimal places

10. Molar Mass (#g = 1 mol) 6.02  10 23 Particles=1 mol MASS IN GRAMS MOLES NUMBER OF PARTICLES Mass from periodic table Particles = Molecules Formula units Atoms

11.  carbon  aluminum  zinc 12.01 g/mol 26.98 g/mol 65.39 g/mol Molar Mass Examples

12. What about compounds? To find the mass of one mole of a compound 1.Determine the # of moles of the elements 2.Find out how much they weigh 3.Add them up The units are gmol -1

13. 2H(1.01) = 2.02 + 1O(16.00) = +16.00 18.02 18.02 gmol -1  Water - H 2 O Molar Mass Examples  Sodium Carbonate - Na 2 CO 3 2Na(22.99) = 45.98 1C(12.01) = 12.01 +3O xygen (16.00) = 48.00 105.99 105.99 gmol -1

14. Molar Mass Problems 1.Determine the mass of one mole of each of the following compounds: 1.CO 2 2.Bromine 3.H 2 4.Al 2 (SO 4 ) 3 1. 44.01 g 2. 159.80 g (It’s diatomic!) 3. 2.02 g 4. 342.17 g

15. Converting Number of Moles to Grams 2c. Calculate the number of grams for 4.08 X 10 -8 mol of barium nitrate. Answer: 1.07 X 10 -5 g Ba(NO 3 ) 2 4.08 X 10 -8 mol Ba(NO 3 ) 2 X 261.3 g Ba(NO 3 ) 2 = 1 mol Ba(NO 3 ) 2 1 mol Ba(NO 3 ) 2 What will the conversion factor look like if the problem asked for how many moles are in 4.08 g of barium nitrate? 1 mol Ba(NO 3 ) 2 261.3g Ba(NO 3 ) 2