1. Chapter 10 “Chemical Quantities”
Yes, you will need a calculator for this chapter!

2. Jan 26th and 27th
What is the mole?
Give a definition and a number

3. You can measure mass, volume, or you can count pieces.
How do we measure items?
You can measure mass, volume, or you can count pieces.
We measure mass in grams.
We measure volume in liters.
We count pieces in MOLES.

4. Moles (is abbreviated: mol)
Avogadro’s number.
1 mole = 6.02 x of the representative particles.

5. Representative Particles
The smallest pieces of a substance
Most elements = atoms
BrINClHOF = molecules because they always come in two’s
Br2 I O2 etc
Covalent compounds = molecules
H2O, SO2
Ionic compounds = formula units
NaCl = 1 formula unit
Something with a charge= Ion

6. Representative Particles
CO2 Fe
CaO
Li+1
Nitrogen gas
Sulfur

7. Conversion Factors 2 possible conversion factors for the mole 1 mole
6.02 x 1023 representative particles OR
6.02 x 1023 representative particles
1 mole

8. How many molecules are in 2.12 mole of carbon dioxide?
Conversion Factors
Using the conversion factors we can determine the number of atoms that are in a mole of a compound or how many moles are in a sample of a compound
How many molecules are in 2.12 mole of carbon dioxide?
2.12 mole CO2
6.02 x molecules of CO2
= _________ molecules of CO2
1.28 x 1024
1 mole CO2 1

9. Practice Problem #1
Magnesium is a light metal that is used in the manufacture of aircrafts, automobile wheels, and tools. How many moles of magnesium is x 1023 atoms of magnesium?
1 mole of Mg
1.25 x 1023 atoms Mg
0.208
=__________ moles of Mg
6.02 x 1023 atoms Mg 1

10. Try This How many moles are in 2.4 x 1023 formula units LiO
How many formula units are in 1.2 mol LiO

11. V. Chemical Measurements
Atomic Mass measured in amu
Atomic mass units
Bottom number on the periodic table
Find the atomic mass of each atom
Mass of O
16.0 amu
Mass of Fe
55.8 amu
Mass of C
12.0 amu

12. Mass of a Compound
FORMULA MASS – sum of the atomic masses in a compound
What is the mass of one molecule of water?
H2O – 2 hydrogen atoms and 1 oxygen
2 (1.01 amu) + 1 (16.0 amu) = 18.0 amu
Find the mass of C2H3O2
C: 2 atoms x 12.0 amu = amu
H: 3 atoms x 1.01 amu = amu
0: 2 atoms x 16.0 amu = amu
Total = amu
Find the mass of Sr(NO3)2

13. Molar Mass Mass of 1 mole of something = its MOLAR MASS
Molar mass = atomic/formula mass in grams

14. Practice Problems 1 mol Fe = ______ g Fe 1 mol O₂ = ______ g O₂
1 mol CaCO₃ = ______ g CaCO₃

15. Practice Problems 1 mol Fe = _55.8_ g Fe 1 mol O₂ = _32.0_ g O₂
1 mol CaCO₃ = _100_ g CaCO₃

16. 10.2

17. Conversion Factors Involving Molar Mass
There are two possible conversion factors relating molar mass and number of moles
1 mole
molar mass OR
1 mole
molar mass
What is the mass of 3.25 mole of potassium?
Follow the steps for conversion problems
39.1 g of K
3.25 mole K
127.1
= ___________ g of K
1 mole K 1

18. Practice Problem #1 How many moles is 5.69 g of NaOH? 0.142 mole NaOH
5.69 g NaOH
40.0 g NaOH 1

19. Practice Problem #2
When iron is exposed to air it corrodes to form red-brown rust. Rust is iron(III) oxide. How many moles of iron(III) oxide are contained in 92.2 grams of iron(III) oxide?
1 mole Fe2O3
0.577
92.2 g Fe2O3
= moles of Fe2O3
160 g Fe2O3

20. VII. Standard Temperature and Pressure (STP)

21. Practice Problem #1 How many moles is 5.67 L of O2 at STP?
= moles of O2
0. 253
1 mole O2
5.67 L O2
22.4 L O2 1

22. Practice Problem #2 What is the volume of 8.8 g of CH4 gas at STP?
12.3
8.8 g CH4
1 mole CH4
22.4 L CH4
CH4
= _______ L CH4
16.1 g CH4
1 mole 1

23. Summary of Conversion Factors
These four items are all equal:
a) 1 mole
b) molar mass (in grams/mole)
c) x 1023 representative particles
d) 22.4 L of gas at STP

24. The Mole Road Map for Conversion Factors

25. Chapter 10 Section 3
Chemistry

26. Essential Questions How do you calculate percent composition?
What is an empirical formula?
How can you tell the difference between an empirical formula and molecular formulas?

27. Percent Composition
Percent composition is the percent by mass of an element within a compound.
There are two ways of finding percent composition:
Percent= part/whole
Eg. How to find your percent on a test

28. Percent Composition (cont)
Propane (C3H8) is a fuel used commonly in gas grills, find the percent composition of propane.
%mass C= 3*C = 3* = 36.03
3*C+8*H = 3* * =
% mass C = 81.7%
% mass H- can set up the same way, or total = 100%, so
% mass H= 100% % = 18.3 %
X 100

29. When a g sample of a compound containing only magnesium and oxygen is decomposed, 5.40 g of oxygen is obtained. What is the percent composition of this compound?
%mass O = 5.40g/13.60 g x100
%mass O= 39.7%
% mass Mg = 100% % = 60.3%

30. Percent Composition (cont)
Find the percent comp for a 2.50 g sample containing g Cu and 2.44 g Zn.
Find the percent comp of CO2
Find percent comp (NH4)2CO3
Find percent comp of NH3
Find percent comp of Fe2(SO4)3

31. Formulas
The empirical formula of a compound shows the smallest whole-number ratio of the atoms in the compound.
The molecular formula of a compound is either the same as its empirical formula, or it is a simple whole-number multiple of its empirical formula.

32. Formulas (cont)
Identify if the following formulas are empirical or molecular , and what would the empirical formula be?
N2O4
H2N CH
C3H6

33. Essential Questions How do you calculate percent composition?
What is an empirical formula?
How can you tell the difference between an empirical formula and molecular formulas?