The Mole
The Mole
What is a mole?
A mole is a QUANTITY of whatever you are measuring…
1 mole = 6.02 x 1023 of whatever you are measuring
Just like 1 dozen = 12 of whatever you are measuring
Or a couple of things = 2 things
What is a mole?In chemistry a mole measures the number of atoms or molecules
1 mole = 6.02 x 1023 atoms or molecules
Why? 6.02 x 1023 is the number of carbon atoms in 12.01 grams of Carbon
6.02 x 1023 is also known as AVAGADRO’S NUMBER
How Big Is a Mole?The volume occupied by one mole of softballs
would be about the size of the Earth.
How many… dollars would you have if you have 2 moles of dollars?
We would find this out by converting from moles to dollars using Avogadro's number
We do this by doing a unit conversion
Unit Conversion Set Up1. Write down your starting amount2. Write down your conversion factor
(__ starting amount = ___ ending amount)• make sure that your units cancel out
3. Complete the multiplication or division problem to find
the end amount
Converting from moles things
# of moles x 6.02 x 1023 things = # of things 1 mole
How many dollars would you have if you have 2 moles of dollars?
2 moles x 6.02 x 1023 dollars = 1.2 x 1024 dollars 1 mole
More ExamplesHow many atoms of water would you have if you have 3 moles of water?
How many atoms of Helium would you have if you have 5 moles of Helium?
Converting from things moles
# of things x _____1 mole ___ = # of moles 6.02 x 1023 things
It would take 2,103,674,750 pennies to circle the earth, how many moles is this?
2,103,674,750 pennies x ___1 mole _ = 3.49 × 10-15 moles 6.02 x 1023 pennies
More Examples
If you have 9,000,000 atoms of water how many moles of water would you have?
If you have 7,500,000 atoms of Helium how many moles of Helium would you have?
SIMPLEGRAM – MOLE CONVERSIONS
Review
1 mole = 6.02 x 1023 “things”
In chemistry those “things” are particles like atoms and molecules
When converting between atoms and moles it doesn’t matter what the type of molecules or atoms are.• The conversion is the same whether you are
converting Water, Sodium, or any other element/molecule
TodayWe are going to learn two more conversions:• Grams to moles• Moles to grams
When converting between grams and moles you need to look at WHAT you are converting.• The atomic mass of the element is your
conversion factor• The atomic mass of an element is the number of
grams of that element in 1 mole
Converting between grams and moles
Grams to moles: DIVIDE by mass of element# of grams x ___1 mole ___ = # of moles
atomic mass
Moles to grams: MULTIPLY by mass of element# of moles x atomic mass = # of grams
1 mole
Where do you find the atomic mass of an element?
Grams Moles ExamplesYou have 20 grams of Helium, how many moles do you have?
20 grams x ___1 mole ___ = 5 moles of Helium 4.00 grams
You have 50 grams of Oxygen, how many moles do you have?
Moles Grams ExamplesYou have 3 moles of Chlorine, how many grams of chlorine do you have?
3 moles x 35.45 grams = 106.45 grams 1 mole
You have 4 moles of Lithium, how many grams do you have?
ADVANCED GRAM – MOLE CONVERSIONS
Molar Mass
When you are converting between grams and moles for a molecule (example – H2O) you need to use the molar mass to convert
The molar mass is the atomic mass of each element in the molecule added up
Calculating Molar MassCalculating Molar Mass of H2O:
H: 1.008 x 2 There are 2 Hydrogen’s so you= 2.016 have to multiply the weight of
Hydrogen by 2O: 16.00
2.016 + 16 = 18.016 grams
Another example…
Calculate the molar mass of KMnO4 (#1 on WS)
K = Mn = O =
Calculating Molar Mass with Parenthesis
What is the molar mass of Ca(NO3)2? (#4 on WS)
• Number outside the () gets multiplied to everything inside the ()
Ca = N = O =