1. Unit 5
The Mole

2. Molecular and Formula Mass
Atomic mass unit (u) = the unit of mass for atoms
Molecular mass is the sum of the masses of all atoms in a molecule
Formula mass is the sum of the masses of all atoms in a formula unit of an ionic compound

3. Examples Molecular mass of H2O is Formula mass of Ca(NO3)2 is 18 u
1 Ca atom = 1 x 40.1
2 N atoms = 2 x 14.0
6 O atoms = 6 x 16.0
Sum is u

4. Assignment
Complete:
Exercises 1-2 page 80
10 points
Due next class

5. Avogadro’s Number 6.02 x 1023 Avogadro’s number is equal to 1 mole
Makes working with large numbers easier
Instead of saying you have 12,000,000,000,000,000,000,000,000 molecules of NH3, you can say you have 19.9 moles of NH3

6. 6.02 x 1023 = 1 mole How big is a mole? If there were 1 mole of
people, it would take 120
trillion Earths to
accommodate them!
6.02 x 1023 = 1 mole

7. The Mole 1 mole = 6.02 x 1023 of anything
1 mole of atoms is _______ atoms
1 mole of baseballs is ______ baseballs
1 mole of dimes is ______ dimes
Molar mass is the mass of one mole of molecules, atoms, ions, or formula units

8. Conversions Use the factor label method Grams to moles Moles to grams
Take the amount in grams and divide by the molar mass of that compound
Moles to grams
Moles multiplied by the molar mass
Molecules to moles
Divide the number of molecules by 6.02 x 1023
These conversions can also be combined

9. Conversions

10. Assignment
Complete:
Problems 3-8 page 83
10 points
Due tomorrow

11. Moles and Gases One mole of any gas is 22.4 Liters
One mole of oxygen gas = ______ L
One mole of CO2 gas = ________ L
One mole of Neon gas = _______ L

12. The Mole Song
A mole is an animal that burrows in the ground,Or a spot on your chin that you gotta shave around.But there's another kind of mole of interest to me,That's the kind of mole they use in chemistry. 
Chorus: A mole is a unit, or have you heard, Containing six times ten to the twenty-third, That's a six with twenty-three zeros at the end, Much too big a number to comprehend.

13. Mole song
Say you had a mole of pennies to distribute 'round the world,Give to each of the five billion grownups, boys, and girls,There wouldn't be a single soul down and out of luck,Cause everybody in the world would get a trillion bucks. 
Or say you had a mole of paper and stacked it toward the sky,Paper's awful thin, but that pile would get so high,It'd reach up into outer space, in fact I think you'd find,It'd go up to the moon and back, eighty billion times. 
Chorus

14. Mole song
Suppose a mole of marshmallows fell upon the planet,Over each square inch of land and sea, think that you could stand it?That layer would be twelve miles high and of course block out the sun,We're talking close to five million trillion tons. 
Well, maybe we could save ourselves if we all started eatin',One marshmallow each second, not two 'cause that'd be cheatin'.With five billion people munching, how long do you think it'd take?Forty million years--and that's without a bathroom break. 
Chorus

15. Mole song
But say you had a mole of atoms, would the pile be immense,Should I say the answer now, or leave you in suspense?Well, atoms are so very, very small, you understand,You could hold a mole of atoms in the palm of your hand. 
So shake a little sugar in the middle of your palm,Now you don't want to spill it, so try and stay calm.You hardly can imaging and barely realize,There's more atoms in that sugar than stars up in the sky. 
Chorus

16. Moles in Solution
Molarity (M) is the ratio between the moles of dissolved substance and the volume of solution
M = mol of solute/dm3 of solution

17. Molarity calculations
What is the molarity of 2.5 x 102 cm3 of solution containing 9.46 g CsBr
M = mol solute/dm3 solution
Convert g to moles
9.46g/213 g = mol CsBr
Convert cm3 to dm3
2.50 x 102 cm2/1000 = dm3
Solve
mol/0.250 dm3 = M CsBr

18. Molarity calculations cont…
Those three steps can be combined into one continuous chain
9.46 g 1 mol 1000 cm3=
2.50 x 102 cm3 213 g 1 dm3
= M CsBr

19. Making a solution
How would you prepare 5.0 x 102 cm3 of a M solution of MnSeO4?
5.0 x 102 cm3 1 dm mol 198 g =
1000 cm3 1 dm3 1 mol
= 13.2 g
So, you would need to dissolve 13.2 g MnSeO4 in enough water to make 5.0 x 102 cm3 of solution

20. Assignment
Complete:
Problems 9-16 on page 85
Due by end of class

21. Percent composition
The percentage composition of a compound is a statement of the relative mass each element contributes to the mass of a compound as a whole
Calculations
Find the mass of each element
Divide each by the formula mass
Multiply each by 100 to get a percentage

22. Empirical Formulas
The empirical formula is the simplest ratio of atoms in a compound
H2O2  HO
Calculations
Determine the moles of each element in the compound
Divide the number of moles by the smallest one to get a ratio

23. Empirical Formula from Percentage Composition
Example – see page 88
Change % to grams
Change g to moles
Find ratio

24. Assignment Complete: 17-22 page 86-87 23-26 page 89 10 points
Due tomorrow

25. Molecular Formulas
A molecular formula shows the actual number of atoms of each element in a molecule
Problems
The molecular mass of benzene is 78.0 u and its empirical formula is CH. What is its molecular formula?
Molecular mass/empirical mass
78.0/13 = 6
C6H6

26. Hydrates Hydrates are crystals that contain water molecules
NiSO3•6H20 means the one molecule of NiSO3 is being adhered to by 6 molecules of water
Hydrate calculations

27. Assignment Complete: 27-31 page 90 and 32-35 page 92 10 points
Due tomorrow

28. Chapter Review
Complete practice exam