1. The mole
Chapter 7 p. 224
Unit 3
“Hard work has made it easy. That is my secret. That is why I win”
- Nadia Comaneci, gymnast

2. 7.1 Intro to the mole
A dozen is a useful unit to use when baking with eggs
But a dozen is not a useful unit to use when working with atoms and molecules
You could not even see a dozen atoms!
Instead of using a dozen, chemists use a counting unit called THE MOLE
(abbreviated as mol )

3. 7.1The Mole
Notes
TheSIunitusedtomeasureatomsandmolecules(particles)Themoleisdefinedintermsoftheisotopecarbon-12(12gramsofC-12containsonemoleofatoms).
The SI unit used to measure atoms and molecules (particles). The mole is defined in terms of the isotope carbon-12(12 grams of C-12 contains one mole of atoms).
Avagadro’s number x 1023

4. 7.1 The mole One dozen eggs contains 12 eggs.
One mole of carbon contains x 1023 carbon atoms.

5. 7.1 The mole

6. 7.1 Mole Facts Read/listen
One mole of paper would make a stack that would reach to the moon more than 80 billion times
One mole of grains of sand would be more than all of the sand on Miami Beach

7. 7.1 Mole Facts Read/listen
One mole of blood cells would be more than the total number of blood cells found in every human on earth
One mole of inches would be1,616,434 light years, or across our galaxy and back 8 times
One mole of seconds is about 19 quadrillion years, 4,240,666 times the age of the earth, or 954,150 times the age of the universe itself

8. 7.1 mole – mass conversion Learning Target
“Students learn how to convert between mass and moles.”
Overview:
P. 230

9. 7.1 Real World Example scratch paper
What is the mass of 3 bags of m&m’s? (conversion factor: 1 bag = 46.2g)
ANS =
139 g
We use the mass of a bag of m&m’s as a kind of conversion factor

10. 7.1 Mole to mass conversion
What is the mass of 2.5 mole of carbon?
moles x conversion factor = mass
The conversion factor in this problem is called molar mass

11. 7.1 Mole to mass conversion
Molar mass is defined as the mass (in grams) of one mole of substance
The molar mass of any element can be found on the periodic table.
For carbon: 1 mole C = g

12. 7.1 Mole to mass conversion
What is the mass of 2.5 mole of carbon?
(1 mole C = g)
S: 2.5 mol x g/mol
S: 30g

13. 7.1 mole to mass conversion
Practice:
Calculate the mass of 4.5 moles of iron.
1 mole Fe = 55.85g
ANS = 4.5 mol x g/mol
= 251 g

14. 7.1 mole – mass conversion Learning Target
“Students learn how to convert between mass and moles.”
Overview:
P. 230

15. 7.1 Mass to mole conversion
Scratch paper
How many moles are there in 76 g of copper?
(1 mole Cu = g)
ANS = 1.2 mole

16. 7.1 Mass to mole conversion
Calculate the number of moles in 10.6 g of gold.
(1 mole Au = g)
ANS = mol

17. 7.1 Molar mass e.g. 1 mole Mg = 24.31 grams
This equality can be rearranged into two different conversion factors, depending on your given and your unknown
Convention:
given as g / mol
say: “grams per mole”
Same as: 1 bag M&Ms = 46.2 g

18. 7.1 mole to mass conversion
Molar mass can also be used for compounds……..
Practice:
Calculate the mass of 0.45 moles of potassium chloride (1 mole KCl = g)
(molar mass of KCl = g/mol)
ANS = 0.45 mol x g/mol
= 34 g

19. 7.1 Mass-mole conversion Practice p. 252
# 31, 33, 34, 38, 40, 41 (remember to convert kg to g where necessary)
Show work to teacher when complete

20. Summary Mole-to-mass conversion: G: mole U: grams Multiply by g/mol
or, ‘Multiply by molar mass’
Mass –to-mole conversion:
G: grams U: moles
Multiply to mol/g
Or, ‘Divide by molar mass’

21. 7.2 Calculating Molar Mass
Read p
Learning Target
Students learn how to calculate the molar mass of a compound.

22. 7.1 Calculating molar mass of a molecule
Calculate the mass of one mole of propane.
C3H8
ANS = g/mol
Practice:
Calculate the molar mass of octane,
C8H18

24. 7.2 Molar mass calc
Practice:
p. 239
#1a-f
p. 240
#10a-e, 12 a-d

25. Practice
Calculate the mass of 0.35 mole of calcium phosphate, Ca3(PO4)2 Hint: first calculate the molar mass of calcium phosphate = g/mol ANS = 109g
1/28 warmie

26. 7.2 Average Atomic Mass
Why are the atomic masses of the elements not whole numbers?
E.g. Cl is amu
b/c atomic mass is a weighted average

27. 7.2 Average Atomic Mass Chlorine is approx 75% Cl-35 and 25% Cl-37
So the average weighted mass is approx 35.5 amu