1. Warm up 3-13-2015 Take out your homework from last night and leave it on your desk
Get a warm up sheet from the front, complete it NO NOTES
When finished turn it over

3. The Mole

5. Molar Mass Calculating Molar Mass
Also called atomic mass, formula mass, molecular mass
Unit = g/mol
Calculating Molar Mass
Use the average atomic mass from the periodic table
For atoms = atomic mass
Ex. C = g/mol
Fe = g/mol
For compounds = sum of the atomic masses of the atoms that are in the formula
EX: CaI2 = g/mol + 2 ( ) g/mol = g/mol
EX: (NH4)3PO4 = 3(14.007) + 12(1.0079) (15.999) = g/mol

6. The Mole Mole = the SI unit for how much of a substance or amount
How do you measure how much you have?
Counting (impractical – too many particles)
Weighing
Volume
Particles cannot be counted directly, but we need to know how many particles are there.
In chemistry we use the mole to figure out how many particles there are when we weigh something or measure the volume of something.
Mole = the SI unit for how much of a substance or amount
The mole is a unit similar to dozen- just many more than 12
It tells you how many you have.

7. The Mole 1 dozen = 12 1 gross = 144 1 ream = 500 1 mole = 6.02 x 1023
There are exactly 12 grams of carbon-12 in one mole of carbon-12.

8. Particles  moles or moles  particles
Use Avogadro’s Number =
1 mole = 6.02 X1023 particles
(atoms, molecules, formula units)
*FOR ANY SUBSTANCE
Grams  moles or moles  grams
Use the molar mass from the periodic table.
Liter  moles or moles  liter
For Gases at STP (standard temperature and pressure)
1 mole = 22.4 L

9. I didn’t discover it. Its just named after me!
Avogadro’s Number
6.02 x 1023 is called “Avogadro’s Number” in honor of the Italian chemist Amadeo Avogadro ( ).
I didn’t discover it. Its just named after me!
Amadeo Avogadro

10. Calculating Formula Mass
Calculate the formula mass of carbon dioxide, CO2.
12.01 g + 2(16.00 g) =
44.01 g
 One mole of CO2 (6.02 x 1023 molecules) has a mass of grams

11. Avogadro’s Number
602,214,000,000,000,000,000,000
Avogadro’s # of sheets of paper stacked one sheet on top of another would reach beyond our solar system.
Avogadro’s # of basketballs could create a new planet the size of Earth.
Avogadro’s # of grains of rice would cover the land masses of the Earth to a depth to 75 meters.
Avogadro’s # of pennies. You decided to give away $1 million dollars a day to every person on Earth , it would take more than years to distribute all of your money

12. Mole Relationships Liters Mole Grams Atoms or molecules 6.02 x 1023
Atomic
Mass
Grams

13. Particles Mole Mass (g)
Molar Mass
Avogadro’s Number
22.4 L/mol
Particles
Atoms
Molecules
f.u.
Mole
Mass (g)
Volume (L)

14. Particles
atoms, molecules, or
formula units
Mass
Volume
(Gas at STP)
Molar Mass
22.4
Avogadro’s Number
Mole Conversions

15. Calculations with Moles: Converting moles to grams
How many grams of lithium are in 3.50 moles of lithium?
3.50 mol Li
6.94 g Li
= g Li
24.3
1 mol Li

16. Calculations with Moles: Converting grams to moles
How many moles of lithium are in 18.2 grams of lithium?
18.2 g Li
1 mol Li
= mol Li
2.62
6.94 g Li

17. Calculations with Moles: Using Avogadro’s Number
How many atoms of lithium are in 3.50 moles of lithium?
3.50 mol
6.02 x 1023 atoms
= atoms
2.07 x 1024
1 mol

18. Calculations with Moles: Using Avogadro’s Number
How many atoms of lithium are in 18.2 g of
lithium?
18.2 g Li
1 mol Li
6.022 x 1023 atoms Li
6.94 g Li
1 mol Li
(18.2)(6.022 x 1023)/6.94
= atoms Li
1.58 x 1024

19. Try these on your own!!! ? g = 8 mol Al2(SO4)3
Ex. How many moles are in 8.04*1024 atoms Fe?
? g = 8 mol Al2(SO4)3

20. Calculations with Moles: Using Standard Molar Volume
How many moles of hydrogen are in 100 L of hydrogen at STP?
100 L
1 mol
= mol
4.64
22.4 L

21. Calculations with Moles: Using Standard Molar Volume
How many liters are occupied by 3 moles of oxygen gas at STP?
3 mol
22.4 L
= L
67.2
1 mol

22. Try These!! How many atoms are in 20.04 g Sn?
How many liters are equal to 8 moles of CO2?
How many moles are equal to 2.4 L of O2?
How many grams of O2 are in 2.4 L O2?

24. *Within a formula, subscripts can be considered as the:
Atom & Mole Ratios
*Within a formula, subscripts can be considered as the:
# of atoms within molecules of the compound
the # of moles of that element within moles of the compound. (Since avogadro’s # cancels out)

25. % Composition Total Mass
Percent Composition = The % by mass of each element in a compound.
Mass of part X = % composition
Total Mass
Example: Find the % of Al composition of Al2(SO4)3
*If you had 25.0 grams of this substance, How much would be Al?

26. Ex: Na2CO310H2O . Find the % of water in this hydrate.
EX: Find the % composition of a compound containing tin and chlorine if g of the compound contains 5.74 g of tin.

27. Warm up
Warm up from up front – use notes, 1st grade of new 6 weeks
Turn the Warm up over when you are done

28. Molecular/Empirical Formula
Empirical Formula = smallest whole number ratio of moles of the elements in a compound
Molecular Formula = actual number and kinds of atoms present in a compound
Ex. Molec Formula = N10O5 Emp Formula = N2O

29. Calculating Empirical Formula
An empirical formula is a ratio of moles of each atom in a compound.
Must have the moles of each atom.
*If you are given %, assume that you have 100 grams of the substance then Convert grams to moles.
To find the lowest whole number ratio (mole ratio). Divide each # of moles by the smallest # of moles.
If a # in the ratio is .5 ( ), double everything.
Apply ratio to atoms given as subscripts.

30. To Repeat
Find Moles
*If you are given %, assume that you have 100 grams
Divide each # of moles by the smallest # of moles.
If the ratio is .5 ( ), double everything.
Apply ratio as subscripts.

31. 25.9 grams N and 74.1 grams O
25.9 / 14 = 1.85
74.1 / 16 = 4.631

32. Calculating Molecular Formula
Calculate the empirical formula mass (efm)
Divide a given molar mass (molecular mass) by efm
Gives you the number of emp. form. in your molecular formula
Multiply the emp. form. by that #
Ex. EF = CH4N Molar Mass = 60 g/mol

33. EX: EF = NO2 Molar Mass = 138 g/mol
Ex %C, 1.15 %H, %N, %O
Molar mass = g/mol. Find molecular formula