1. Measurement of Matter: The Mole
How do you measure matter?
What are the three different ways we
Can measure things?
count
mass
volume

2. CONVERSIONS A pair Equals A dozen equals
1 minute equals how many seconds?
1 hour equals how many minutes 2 12 60

3. CHEMICAL QUANTITIES

4. THE MOLE How do we count matter?
Composed of atoms, molecules and ions
The mole is an equality that describes the number of particles in a substance
6.02 x particles,atoms ect.. = 1 mole ( avogadro’s number)

5. Practice Problem
How many moles of magnesium is 1.25 x atoms of magnesium
1. Start with what you know
1.25 x atoms of Mg mole of Mg
6.02 X atoms of mg
= mol Mg

6. REVIEW 1. How many atoms are in 1.14 mol of SO3
2. How many moles are in 4.65 x10 24 molecules of NO2

7. How many atoms are in 1.50 mols of Na
determine the number of moles in 4.96 x molecules glucose

8. Mass of a Mole in an element
The atomic mass of an element expressed in grams is the mass of a mole of the element = molar mass
Ex. Carbons molar mass = 12.0g
Hydrogens molar mass = 1.0 g
The molar masses of any two elements contains the same number of atoms
12.0 g of carbon = 1 mol = 6.02 x particles
1.0 g of hydrogen = 1 mol = x particles

9. Mass of a mole of a compound
Must know the formula of the compound first
Ex. SO3
1 sulfur ( 1 x 32.1) 32.1 amu
3 oxygen ( 3 x 16.0) = 48.0 amu
molar mass = = 80.1 amu
1 mol has a mass of 80.1 amu

10. Review What is the molar mass of PCl3
How many atoms are in 1.50 mols of Na

11. MASS/MOLE RELATIONSHIPS
Remember: to calculate molar mass you must know the number of grams of each element in one mole of the compound and add the masses of all the elements of the compound
You can use molar mass of an element or compound to convert between the mass of a substance and the moles of a substance

13. calculations Calculate the mass of 3.00 mol of NaCl Molar Mass of NaCl
Total = 53.9 g
3.00 mol
54.9 g NaCl
1 mol NaCl

14. Converting mass to moles
How many moles of Iron (III) oxide are contained in 92.2 g of Fe2O3
92.2 g of Fe2O3 X 1 mol of Fe2O3
160 g Fe2O3
= .58 mol Fe2O3

15. GRAMS TO MOLECULES
How many grams are in 4.65 x10 24 molecules of NO2

16. Review Quiz How many grams are in 4.65 x10 24 molecules of NO2
What is the molar mass of PCl3
What is the mass of 2.25 mol of NaCl

17. QUIZ
How many grams does
4.3 x molecules of MgCl2 have

18. PERCENT COMPOSITION
Percent Composition – the relative amounts of the elements in a compound
Consists of a percent value for each different element in a compound

19. CALCULATIONS
The percent by mass of an element in a compound is the number of grams of the element divided by the mass in grams of the compound, multiplied by 100%
% mass of element = mass of element x 100
mass of compound

20. Practice
Propane (C3H8), the fuel commonly used in gas grills, is one of the compounds obtained from petroleum. Calculate the percent composition of propane
%C = 36.0g (3 X 12) x = 81.8%
44.0g
%H = 8.0g x = 18%

21. REVIEW QUIZ
Propane (C3H8), the fuel commonly used in gas grills, is one of the compounds obtained from petroleum. Calculate the percent composition of propane
Calculate the number of moles in 0.50 g of sodium bromide (NaBr)

22. Review Quiz; % composition
What is the percent composition of baking soda NaHCO3

23. Empirical/Molecular Formulas
The lowest whole number ratio of the atoms of the elements in a compound
Molecular formula H2O2
Empirical formula HO

24. Determining empirical formulas
A compound is analyzed and found to contain 70.9% potassium and 29.1%sulfer. What is the empirical formula of the compound?
Percent you can assume 100
70.9 g x 1 mol K = 1.8molK
39 g K
29.1 g x 1 mol S = .91 mol S
32 g S
HINT:
% TO MASS
MASS TO MOLE
DIVIDE BY SMALLEST
MULTIPLY TILL WHOLE

25. Divide each molar quantity by the smaller number of moles 1. 85/
Divide each molar quantity by the smaller number of moles /.91 = 2 K = .91/.91 = 1 S
K2S

26. MOLECULAR FORMULAS
Molecular formulas can be determine by empirical formulas.
First calculate the empirical formula mass
Divide molecular mass by formula mass
Multiply each subscript in your formula by the factor

27. Practice problem
A compound with an empirical formula of CH2O has a molecular mass of 90 amu. What is it’s molecular formula
Determine empirical formula mass
C = 12 x1
H = 1 x 2
O = 16 x 1 30

28. Divide the molecular mass by the empirical formula mass to determine the multiple
90/30 = 3
Multiply the empirical formula by the multiple to find the molecular formula
[CH2O] X 3 = C3H6O3

29. REVIEW QUIZ
A compound has 67.6% Hg, 10.8% S, and 21.6% O. Determine the empirical formula
Find the molecular formula of ethylene glycol (antifreeze). The molar mass is 62g/mol and the empirical formula is CH3O