Moles, Molar Mass, &
Unit Conversion
How do they determine the # of pages in a
ream?
Do they count? 500 sheets
Do they mass the paper? 20 lbs or 9.071847 Kg
Which would be more accurate?
Overview
What is a Mole?
What is molar mass?
How is molar mass determined?
Unit conversion with molar mass.
What is a mole?
A mole is a number which can refer to atoms, molecules, or
particles.
One mole = 6.02 x
23
10
particles = Avogadro’s #
In equations, we abbreviate it as “mol.”
What is molar mass?
Molar mass is the mass of one mole of a substance.
e.g. 1 mol Li = 6.94 g Li
Practice:
What is the mass of one mole of Ni?
How is molar mass determined?
Knowing the average mass of substances allows us to count
by weighing.
How many pages in a ream?
10 sheets = ???
1 ream = ???
What is molar mass?
Molar mass is the mass of one mole of a substance.
Practice:
What is the mass of one mole of Ni? 58.69 g Ni
What is molar mass?
Molar mass is the mass of one mole of a substance.
Practice:
What is the mass of one mole (the molar mass) of SO2?
What is molar mass?
Molar mass is the mass of one mole of a substance.
Practice:
What is the mass of one mole (the molar mass) of SO2?
32.07 g + 2x(16.00 g)=64.07 g SO2
What is molar mass?
Molar mass is the mass of one mole of a substance.
Practice:
What is the molar mass of Cu3(BO3)2?
What is molar mass?
Molar mass is the mass of one mole of a substance.
Practice:
What is the molar mass of Cu3(BO3)2?
3x(63.55 g)+2x(10.81 g + 3x(16.00 g))
= 190.65 g + 117.62 g = 308.27 g
Molar Mass Practice
Find the molar mass of NaBr.
Find the molar mass of (NH4)2CO3.
Find the molar mass of C6H12O6.
Molar Mass Practice
Find the molar mass of NaBr. 102.9 g/mol
Find the molar mass of (NH4)2CO3. 96.0 g/mol
Find the molar mass of C6H12O6. 180.0 g/mol
Unit Conversion with Moles
If we are given the # of moles,
we can determine the number of
grams.
1.
Determine the molar mass.
2.
Calculate the other apex.
g
mol
g/mol
Unit Conversion with Moles
Practice: 16.04 g CH4 =
? mol CH4
Unit Conversion with Moles
Practice: 16.04 g CH4 =
? mol CH4
1 mol CH4 = 12.01 g + 4x1.008 g = 16.042 g CH4
Unit Conversion with Moles
Practice: 16.04 g CH4 =
? mol CH4
1 mol CH4 = 12.01 g + 4x1.008 g = 16.042 g CH4
16.04 g CH4 x (1 mol CH4 /16.042 g CH4 )
Unit Conversion with Moles
Practice: 2 mol Fe2O3 = ? g Fe2O3
Unit Conversion with Moles
Practice: 2 mol Fe2O3 = ? g Fe2O3
? g /mol Fe2O3 = 2x(55.85) + 3x(16.00)
= 111.7 + 48
= 159.7 g /mol Fe2O3
Unit Conversion with Moles
Practice: 2 mol Fe2O3 = ? g Fe2O3
? g /mol Fe2O3 = 159.7 g /mol Fe2O3
2 mol Fe2O3 x 159.7 g /mol Fe2O3 = 319.4 g Fe2O3
Unit Conversion Practice
How many moles are in 25.0 g of water?
Unit Conversion Practice
How many moles are in 25.0 g of water? 1.39 mol H2O
Unit Conversion Practice
How many grams are in 4.5 moles Li2O?
Unit Conversion Practice
How many grams are in 4.5 moles Li2O? 134.1 g Li2O
Homework
Review the section on molar mass (pgs. 130-136).
Do “Mole Practice”