Chapter 10
Chemical Quantities
The MOLE
What is a mole?
A) A blind furry animal.
B) A brown mark on your
body.
C) An important
Chemistry concept.
D) All of these.
As you may have guessed, D is
the correct answer!!
Although a mole might be cute and
fuzzy, we are going to focus on the
Chemistry concept.
A mole is a counting unit.
Just like:
•
•
•
•
12 eggs equals a dozen eggs
144 pencils equals one gross of pencils
60 seconds equals one minute
500 sheets of paper equals one ream
One mole equals 6.022 x 1023
particles
• So one mole of eggs would be 6.022 x 1023
eggs
• One mole of pencils would be 6.022 x 1023
pencils
• And so on...
Where did the mole come from?
• The unit, called the mole (or mol), is
defined as the number of atoms in exactly
12g of the carbon-12 isotope
• The number of particles in one mole, 6.022
x 1023, is known as Avogadro’s constant or
number.
• This was named after Amedeo Avogadro
(1776-1856) whose ideas were crucial to
the early development in Chemistry
Amadeo Avogadro
6.022 x 1023 is a very large
number!
• If we did not use scientific notation to write
out 6.022 x 1023, we would write out 6022
with 20 zeros after it.
602,200,000,000,000,00
0,000,000
Wow that is a BIG number!!
Imagine that we had a mole of
gumballs.
If all 6 billion people on Earth were
to do nothing but count the gumballs
in one mole at the rate of one gumball
per second, it would take over 3
million years to count all the
gumballs!! See pg. 316 for more
What is all of this used for?
• Avogadro’s constant can be used to convert an
amount of moles into the equivalent number of
atoms or grams.
Mole Problem Solving Strategy
• Example: How
many eggs are
in 8 dozen?
This strategy can also be used with
the mole concept.
• How many
atoms are in
3.5 moles of
copper?
convert from atoms to moles
How many moles are in 3.01
23
x 10 atoms of Sodium?
1. How many atoms are present in 2.25 moles
CO2?
2. How many oxygen atoms are in 5.2 mol of
water?
3. Find the molar mass of Cu(NO3)2 ?
4. What is the mass of 1.00 mol of Cu(NO3)2 ?
If you showed all the steps, the
correct answers are:
1. 4.06 x 1024 atoms
2. 3.1 x 1024 atoms O
3. 187.57 g/mol
3. 188 g
some mole jokes!
• Who is Avogadro’s favorite actor?
Mol Gibson…. Ha ha!
• Where did Avogadro go on Saturday?
The shopping mole.
• What did Avogadro have on his pancakes?
Molasses!! (I know you may think these jokes
are remolting, but you will grow to love
them!!)
One more joke
•Why did Avogadro look forward to
the year 2000?
•It was the start of the new
molennium!!!
Sec. 10.1 Homework: Q’s pg. 309
3. How many moles is 2.80 x
24
10 atoms Si?
• 4. How many moles is 2.17 x
1023 representative particles Br?
Q’s pg. 311
• 5. How many atoms are in 1.14 mol
SO3?
• 6. How many carbon atoms are in 2.12
mol C3H8?
• How many H atoms are in 2.12 mol
C3H8?
Q’s pg. 315
• 7. Find the molar mass of
PCl3?
• 8. What is the mass of 1.00
mol NaHCO ?
Q’s pg. 315 Lesson check 10.1
• 12. Calculate If a dozen apples has a mass
of 2.0 kg and .20 bushel is 1 dz apples, how
many bushels of apples are in 1.0 kg of
apples?
• 13. How many moles is 1.50 x 1023
molecules of NH3?
Pg. 315 continued
• 14. How many atoms are in
1.75 mol of CHCl3?
• 15. What is the molar mass
of CaSO ?
Ch 10 section 2 : Mole – Mass
relationships
Find the number of moles
in 25.6 g of Na2SO4.
•Calculate the mass in
grams of 3.50 moles of
iron(III) sulfate.
Mole-Volume relationship
• Avogadro’s hypothesis states that
equal volumes of gases at the
same temperature and pressure
contain equal numbers of
particles.
• Note: volume of a gas varies with
a change in Temp. and pressure
• Standard temperature and
pressure (STP) means a
temperature of 00C and a
pressure of 1 atmosphere (atm).
• For any gas:
• 1 mol = 22.4 L = 6.02 x 1023
What is the volume of
0.850 mol nitrogen gas?
How many moles are in
55.36 L of Neon?
Molar mass and density
The density of a gas is 1.7824
g/L at STP. What is the molar
mass of the gas?
Ch 10 section 3
• Percent Composition of a
compound:
Fe2(SO4)3
Calculate mass of element in a
compound
Calculate the mass of iron in
57.2 g Fe2(SO4)3.
• Hint: use % comp. from
previous question.
Empirical Formulas
Empirical Formula (simplest formula) –
lowest whole number ratio of atoms in a
compound.
EX./ Given:71.72 % Cl, 16.16% O and
12.12 % C. Calculate empirical formula.
Molecular Formulas
• Determine the molecular formula for a
compound that is 94.1% O and 5.9 % H
with a molar mass of 34 g/mol.