1. AP Chem Turn in Chromatography Lab. Today: Mole, EF & MF Review
Due Dates:
Unit 1 MC Packet due Wed 9/12
Unit 1 Test Th 9/13 and Fri 9/4

2. Definitions One Mole = 6.022 x 1023 particles
This is Avogadro’s number.
Molar Mass: The mass of one mole of a substance in grams.
Percent Composition: Identifies the elements present in a compound as a mass % of the total compound mass

4. Molar Mass & Percent Composition
grams
grams
grams
47.70 % Cr
52.30 % F
15.77% Al
28.11% S
56.12 % O
38.67% K
13.86% N
47.47% O
*Remember: multiply the subscripts when there is a parentheses

5. Molar Conversions Conversion Factors:
Convert between grams, moles, and molecules using dimensional analysis
Conversion Factors:
1 𝑚𝑜𝑙𝑒 ___𝑔𝑟𝑎𝑚𝑠 or ____𝑔𝑟𝑎𝑚𝑠 1 𝑚𝑜𝑙𝑒 (Molar Mass)
1 𝑚𝑜𝑙𝑒 𝑥 𝑚𝑜𝑙𝑒𝑐𝑢𝑙𝑒𝑠 or 𝑥 𝑚𝑜𝑙𝑒𝑐𝑢𝑙𝑒𝑠 1 𝑚𝑜𝑙𝑒

6. 41.98 gNaF
4.5 mol NaF
= 189 g NaF
1 mol NaF

7. Molar Conversions
How many grams are in 4.5 moles of sodium fluoride, NaF? 189 grams
How many moles are in 98.3 grams of aluminum hydroxide, Al(OH)3? 1.26 mol
How many molecules are there in 450 grams of sodium sulfate, Na2SO4? 1.91 x 1024 molecules
How many grams are there in 7.5 x 1023 molecules of sulfuric acid, H2SO4? 122 grams

8. Empirical vs. Molecular Formula
Empirical Formula = simplest/smallest ratio of each element in a compound
Molecular Formula = total number of atoms of each element in a compound
Remember: the empirical and molecular formula can be the same!

9. C4H7
CH2
C6H12
84/14 = 6
14.03 g/mol

10. CaCl2
C4H8O4
C2F6

11. Mass Spectrometer Analyzes Samples by Mass and % Composition

12. Mass Spectrometer Signal for Neon *you need to analyze the data!

14. 1 mol C C: H: O:
3.758 g C
= mol C
12.01 g C
1 mol H
0.316 g H
= mol H
1.01 g H
1 mol O
1.251 g O
= mol O
16.00 g O

15. mol C
= 4 mol C
mol
mol H
= 4 mol H
C4H4O
mol
mol O
= 1 mol O
mol

16. Practice
C4H4O
CaO2H2 ( Ca(OH)2 )

18. 1 mol Fe
Fe: S:
63.52 g Fe
= mol Fe
55.85 g Fe
1 mol S
36.48 g S
=1.138 mol S
32.06 g S

19. Practice
FeS
A) C2H4O B.)C6H12O3

20. 25.94% N 74.06% O. Determine Empirical Formula
25.94 𝑔 𝑁 × 1 𝑚𝑜𝑙𝑒 𝑁 𝑔 𝑁
74.06 𝑔 𝑂 × 1 𝑚𝑜𝑙𝑒 𝑂 𝑔 𝑂
=1.85 mole N
=4.63 mole O
1.85 mole N
What happens when you divide and you don’t get a whole number?
=1 N
1.85 mole
4.63 mole O
=2.5 O
1.85 mole

21. “NO2.5”
We need to multiply the entire thing by a whole number so that we can get whole number subscripts
NO2.5 x 2
= N2O5

22. What happens if you don’t get whole number mole ratios?
If when you divide all the # of moles by the smallest # of moles and your mole ratios end in:
Multiply all mole ratios by ____ to get all whole numbers for your mole ratio
~0.5 (1/2)
X 2
~.33 (1/3) ,
~.66 (2/3)
X 3
~0.25 (1/4),
~0.75 (3/4)
X 4