1. Warm-Up
Calculate Molar Mass
K2O
PCl5
LiF

2. The Mole...
J. McLeod

3. Objectives Describe methods of measuring the amount of something.
Define Avogadro’s number as it relates to a mole of a substance.
Distinguish between the atomic mass of an element and its molar mass.
Describe how the mass of a mole of a compound is calculated.
Describe how to convert the mass of a substance to the number of moles of a substance, and moles to mass.
Describe how to convert the volume of a substance to the number of moles of a substance, and moles to volume.

4. What is a mole?

5. The mole… Abbreviated (mol)
It is an amount, such as…
Pair: 1 pair of shoelaces = 2 shoelaces
Dozen: 1 dozen oranges = 12 oranges
Gross: 1 gross of pencils = 144 pencils
Ream: 1 ream of paper = 500 sheets of paper

6. 1 mole = 6.02 x 1023 Definition That’s 602,000,000,000,000,000,000,000
We call this number Avogadro’s number after Amadeo Avogadro ( )

7. Definition
Field Trip!!!!

8. Definition
= 1 mol C
= 6.02 x 1023 atoms C
= 12 grams C

9. Atomic Mass is the average of all isotopes of a given element.
Review
Atomic Mass is the average of all isotopes of a given element.
1 amu = 1/12 of a C-12 atom.

10. Molar Mass Atomic Mass = Molar Mass for an element
Molar mass is the mass of 1 mole of a compound.
It is calculated by adding each of the atomic masses of the elements making up the compound.
Units for molar mass are g/mol.

11. Diatomics
Diatomics…. You need a highlighter!!

12. Calculating Molar Mass
Example #1: What is the molar mass of carbon (C)? C: 1 x = g/mol 1 mole of carbon = 12 grams of carbon Example #2: What is the molar mass of oxygen (O2)? O: 2 x = g/mol 1 mole of oxygen = grams of oxygen.

13. Calculating Molar Mass
Example #3: What is the molar mass of Water (H2O)?
H: 2 x = g/mol
O: 1 x = g/mol
H2O = g/mol
1 mole of water = grams of water

14. Calculating Molar Mass
Example #4: What is the molar mass of sodium chloride (NaCl)? Na: 1 x = g/mol Cl: 1 x = g/mol NaCl = g/mol 1 mole of NaCl = grams of NaCl

15. 1 mole of Li2Cr2O7 = ___________ g of Li2Cr2O7
Your Turn
Calculate the molar mass for lithium dichromate: Li2Cr2O7
1 mole of Li2Cr2O7 = ___________ g of Li2Cr2O7

16. Molecules, atoms, or ions
Conversion Road Map
Using the flowchart we can convert between moles, mass, molecules, or liters:
Molecules, atoms, or ions
Moles
Grams
Liters
6.02x1023
22.4
Molar mass

17. Rules For Conversion Write Units Map Set Up Problem
Write Given
Use a T box for each step of the map
Make sure your units cancel!
Write your answer with correct units

18. Use Of Molar Mass
How many grams of nitrogen are in 1.25 moles of nitrogen (_______)? Units Map: mol (N2)  grams (N2) 1.25 mol N2
What’s the formula for Nitrogen? 28
grams N2
= 35.0 g N2 1
mol N2

19. Use of Avogadro’s Number
How many atoms of iron are in 2.76 moles of the metal? Map: mol Fe  atoms Fe 2.76 moles Fe
6.022 x 1023
atoms Fe
= 1.61 x 1024
atoms Fe 1
moles Fe

20. Use of Volume
How many moles of carbon monoxide are in 26.7L of carbon monoxide? Units Map L CO  mol CO 26.7 L CO 1
mol CO
= 1.19
mol CO
22.4
L CO

21. Use of Molar Mass & Avogadro’s #
How many molecules of Iodine are in 25g of Iodine (____)? Units g I2  mol I2  molecules I2 25 g I2 I2 1
mol I2
6.022x1023
molecules I2
253.81
g I2 1
mol I2
=5.93x1022 molecules I2

22. Ticket Out The Door
In your groups, compare and contrast the process to convert moles to grams and that to convert moles to atoms or particles.
WHAT’S SIMILAR?
WHAT’S DIFFERENT?