Starter
 Retrieve a Unit 6 Mole Review Packet
from the front table
 Recall dimensional analysis…
1. What were some important methods
you used?
2. How did you convert your units?
Meet the Mole.
Moles
 The mole is a unit of measurement used in
chemistry.
 The unit can be defined in multiple ways.
(We’ll learn 3 today.)
 In its simplest terms, it represents a specific
number.




Dozen = what number?
Pair = what number?
Baker’s dozen = what number?
Mole = 6.022 x 1023
Mole = 6.022x1023 things
 Just like a dozen means 12 of
anything... 6.022x1023 of anything
equals of mole.
 Consider the size of 6.022x1023. Is it
large or small?
 Would you commonly use 6.022x1023
with large things or small things?
Atoms, Elements, &
Compounds
 In chemistry, we are often dealing with
VERY SMALL things.
 Atoms are SUBmicroscopic. In order to
have an amount large enough with
which to really interact, we need quite a
few atoms. 6.022x1023 is the number
that Amadeo Avogadro chose in his lab
using carbon.
Avogadro’s Number
 6.022x1023
 My pet mole is named Avogadro.
Defining the Mole
 Counting
 Weighing
 Amount of Space Needed
Moles & Mass of Compounds
 A compound is a collection of atoms.
 To calculate the mass of one mole of a
compound, you’d need to add up the mass of
all the atoms. This is called the MOLAR MASS.
 Example: 1 mole CH4 = ______ g CH4
 1 C = 12.011 g C
 4 H = 4(1.0079 g H)
 Total = 16.04 g/mol
Another Molar Mass Example
 Calculate the molar mass of sulfur dioxide, a
gas produced when sulfur-containing fuels
are burned.
 SO2




S = 32.07 g
O = 2(16.00 g)
Total = 64.07 g/mol
Can also be expressed as 1 mol SO2 = 64.07 g
Using Molar Mass
 Calculate the molar mass for sodium
sulfate, Na2SO4. A sample of sodium
sulfate with a mass of 300.0 g
represents what number of moles of
sodium sulfate?
 Identify the given and the unknown.
 What is the conversion factor on the mole
map?
 Set up the calculation.
Finding the Number of Atoms
 Aluminum (Al), a metal with a high strength-toweight ratio and a high resistance to corrosion, is
often used for structures such as high-quality
bicycle frames. Compute both the number of
moles of atoms and the number of atoms in a
10.0-g sample of aluminum.
 How many calculations is this prompt asking
me to carry out?
 Concentrate on one calculation at a time
 Continue work on the board.
Finding the Number of Atoms
 A silicon chip used in an integrated
circuit of a computer has a mass of 5.68
mg. How many silicon (Si) atoms are
present in this chip? The average
atomic mass for silicon is 28.09 amu.
Finding the Number of Atoms
 What if they ask you for the number of
atoms of a certain element within the
molecule?
 You must use a Mole Ratio
 Example:
a. How many O atoms are in 10 grams of
water?
b. How many C atoms are in dicarbon
tetrahydride?
Molar Volume
 If converting between the units of
moles and liters of a gas, what
conversion factor is needed?
 1 mole = ________________
 1 mole = 22.4 Liters
 Example: During cellular respiration, a
cell releases 2.1 mol of O2 gas. What
volume is needed to hold that gas?
Partner Practice
 On a clean sheet of paper, show your
work for 10-2 Practice Problems (1-3,
12-14, 17, 18, 23-25).
Independent Practice
(Homework)
 Complete any assigned 10-2 Practice Problems
above, and solve page 211 22 and 23.
As you come in,
 Put your homework on your desk.
 Solve Example 6.7 on your notes Juglone, a dye known for centuries, is
produced from the husks of black walnuts.
The formula for juglone is C10H6O3.
 Calculate the molar mass of juglone.
 A sample of 1.56 g of pure juglone was extracted
from black walnut husks. How many moles of
juglone does this sample represent?
 How many atoms of carbon are present?
Partner Evaluations
 Spend 10 minutes with your partner
comparing work - NOT JUST ANSWERS.
 When you find differences, decide
which version is BEST.
 Mark questions to ask when we meet
back as a large group.
10-2 Practice Problems
 Any questions that you need me to
solve.
As you come in,
 Put your Think Tac Toe on your desk.
 We’ll take your quiz after a quick TTT
check and review time.
 New content begins at 2:40 pm.
 HOMEWORK: 7-2 Section Review 1-3, %
Composition WS 1-3, and Empirical &
Molecular Formula Practice 1-3
Thinking Critically About Moles
 Knowledge Level Station
 Show your knowledge of the mole concept
by labeling the Mole Map graphic
organizer.
 Use the colored pencils to color-code your
organizer.
 RED = COUNTING PARTICLES
 BLUE = WEIGHING SUBSTANCES
 GREEN = AMOUNT OF SPACE TAKEN BY A GAS
Thinking Critically About Moles
 Comprehension Level Station
 Explain the use of the mole map to your
partner. Use the following calculation
prompts in your explanation. Begin your
explanation with “I would use my mole
map to solve this calculation by...”
 Partner One: How many grams of sucrose,
C12H22O11 contain 0.79 moles?
 Partner Two: The number of particles in 0.91
moles of ammonia is _____.
Thinking Critically About Moles

Application Level Station

Use the conversion factors illustrated and
explained on the Mole Map to compute solutions
to the following. Show all of your work.


Calculate the number of grams of cobalt that contain
the same number of atoms as 2.24 g of iron.
Apply the concept of the mole in order to determine
which of the following statements is the most accurate
description of a mole.
a.
b.
c.
d.
The number of atoms in 55.85 grams of iron.
The mass of carbon in a measured sample of carbon.
The number of atoms in any given mass of a molecule.
6.022 x1023 grams of a sample of any element.
Thinking Critically About Moles
 Analysis Level Station
 Use the substances and instruments at the
station. Which substance will create a taller
column in the graduated cylinder: 0.215 mol
C12H22O11 or 0.972 mol NaHCO3? Measure and
record the height of each in mL.
 Compare the molar masses of the two substances.
 If 7 balloons were filled with the 1 mole of each of
the 7 diatomic gases, which balloon would weigh
the most? The least?
Thinking Critically About Moles
 Synthesis/Evaluation Level Station
 Check your homework from last night. Use
a colored pencil to correct your mistakes.
 Leave your corrected homework in the
labeled folder.
Starter
 Polyvinyl chloride, called PVC, which is widely used
for floor coverings (“vinyl”), is made form a molecule
with the formula C2H3Cl.
Calculate the MOLAR MASS of this substance.
 Calcium carbonate, CaCO3 (also called calcite), is the
principal mineral found in limestone, marble, chalk,
pearls, and the shells of marine animals.
 A certain sample of calcium carbonate
contains 4.86 mol. What is the mass in
grams of this sample?
How many oxygen atoms are in 10g sulfur
dioxide?
Percent Composition
 The relative amounts of each element
in a compound are expressed in percent
composition. AKA: percent by mass of
each element
 % of element = grams of element X 100
grams of compound
% Composition Example
 Carvone is a substance that occurs in
two forms, both of which have the
same molecular formula (C10H14O) and
molar mass. One type of carvone give
caraway seeds their characteristic
smell; the other is responsible for the
smell of spearmint oil. Compute the
mass percent of each element in
carvone.
Connecting Moles & Mass %
to Chemical Formulas
 Mass % is easily related to chemical
formulas
 The relationship of moles to chemical
formulas requires a little more
thought...
Type of Chemical Formula:
Empirical Formula
 Empirical formula: lowest whole number
ratio of the atoms of the elements in a
compound
 Ionic compounds are criss-crossed and then
reduced. Ionic compound formulas are nearly
always empirical formulas.
 Empirical formula doesn’t have to be the
same as the actual molecular formula of the
compound.
 CH2O = empirical formula for GLUCOSE
Empirical Formula
 CH2O
 Calculate the mass percent of each element.
 C = 40%
 H = 6.7%
 O = 53.3%
 Isn’t this the reduced formula for: C3H6O3,
C4H8O4, C5H10O5, & C6H12O6
 The mass percent of each of these
compounds is the same.
Type of Chemical Formula:
Molecular Formula
 Molecular formula: actual formula for
the compound which gives the
composition of the molecule
 Glucose shares an empirical formula
with many compounds, but it has its
molecular formula all to itself.
 What is it’s molecular formula?
Calculating Empirical Formula
 Use a simple rhyme!
 % to gram
 Gram to mole
 Divide by the smallest
 Multiply ‘til whole.
Calculating Empirical Formulas
 When an unknown compound is found,
instruments can tell scientists the mass
percent composition of the compound.
 Calculations are required to convert that
series of percentages into a chemical
formula.
 We start by converting to the empirical
formula.
Empirical Formula Example 1:
 An oxide of aluminum is formed by the
reaction of 4.151 g of aluminum with 3.692 g
of oxygen. Calculate the empirical formula
for this compound.
 % to gram = IS DONE FOR YOU
 Gram to mole = dimensional analysis
 Let’s carry out the calculation on the board.
Formula Example 2
 A sample of lead arsenate, an insecticide
used against the potato beetle, contains
1.3813 g of lead, 0.00672 g of hydrogen,
0.4995 g of arsenic, and 0.4267 g of
oxygen.
 Calculate the empirical formula for lead
arsenate. (PbHAsO?)
Calculating Molecular Formula
 Molecular Formula= n(empirical formula)
CH2O = glucose
 We know how to calculate the empirical
formula, but how do we know what
number to multiply it by?
n= molecular formula mass/molar mass of
empirical
Formula Example 3
 Glucose is analyzed and found to have
an empirical formula of CH2O. The
compound has a molar mass of 180.149
g/mol. What is the compound’s
molecular formula?
Formula Example 4
 The most common form of nylon is
63.68% carbon, 12.38% nitrogen,
9.80% hydrogen, and 14.4% oxygen.
Calculate the empirical formula for
nylon.
 If the molar mass of the compound is
226.306g, what is it’s molecular
formula?
Priorities:
1.
2.
3.
4.
The Mole Think Tac Toe
Critical Thinking Stations
Empirical Formula Worksheet
Mole Practice Packet - Chemical
Quantities Section 7.2 1-9
Starter
 Which is the best description of a mole?
a. Mass of carbon in a measured sample of
carbon
b. # of atoms in any given mass of carbon
c. Number of atoms in 12.01 grams of carbon
 How many Hydrogen atoms are in 20g of
H2O2?
 Octane (C8H18), a compound of hydrogen and
carbon, has a molar mass of 114.26g/mol. If
one mole of the compound contains 18.17g
hydrogen, what is it’s empirical formula?
Challenging Molar Mass
Problems
 What mass of strontium contains the
same number of atoms as 15g of
beryllium metal?
 Consider a 5g sample of sodium and a
10.1g sample of an unknown metal.
There are exactly half as many atoms of
the unknown as in the 5 grams of
sodium. What is the unknown metal?
Starter
 What is the percent by mass of
hydrogen in acetic acid?
 A container contains 10g carbon dioxide
at STP, what is the volume the gas?
 The final product in protein metabolism
is urea. Urea contains 20.00% C,
6.73% H, 46.65% N, and 26.64% O.
The molar mass of urea is 60.07g/mol.
Calculate the molecular formula.
Challenging Molar Mass
Problem
 Calculate the number of grams of
potassium that contain the same
number of atoms as 6g of cesium.
 Consider a 10g sample of gold and a 4g
sample of an unknown element. There
are exactly half as many atoms of the
unknown as in the 10 gram of gold.
What is the unknown element?
Starter
 Which weighs more, 1.5 mol of bromine or 15 mol
of lithium metal?
 A single molecule of a compound has a mass of
1.461 x 10-22g. Could it be NO or CF4 ?
 What is the empirical formula for disulfur
tetraoxide?
 Find the molecular formula of a compound that
consists of 56.36% oxygen and 43.64%
phosphorus. The molar mass of the compound is
425.83g/mol.
Challenging Molar Mass
Problems
 A single molecule of a compound has a
mass of 7.0399 x 10-23g. Could it be LiCl
or NaF?
 Consider a 10g sample of nitrogen and a
13g sample of an unknown metal. There
are exactly twice as many atoms of the
unknown as in the 10 grams of nitrogen.
What is the unknown metal?
Bonus (2 pts each)
 A tube contains 25g helium at STP, what
is the volume the gas?
 If a sample contained 10g of Li, how
many lithium oxide formula units would
you have?
 Consider a 20g sample of gold and a 4g
sample of an unknown element. There
are exactly half as many atoms of the
unknown as in the 20 gram of gold. What
is the unknown element?
Empirical / Molecular Formula
 A compound used as an additive for gasoline
to help percent engine knock shows the
following percentage composition:
 71.65% Cl
 24.27% C
 4.07% H
The molar mass is known to be 98.96 g. Determine
the empirical formula and the molecular formula
for this compound.
Empirical / Molecular Formula
 A compound used as an additive for gasoline
to help percent engine knock shows the
following percentage composition:
 71.65% Cl
 24.27% C
 4.07% H
The molar mass is known to be 98.96 g. Determine
the empirical formula and the molecular formula
for this compound.
STARTER
 TAKE 5:
1. Minutes to look over your notes and
important formulas
2. Minutes to ask any last questions
before your test
As you come in,
 Complete Review Stations 1-24. Write down
the station number, your work, and circle
your answer.
 When you have completed the stations,
return to your seat. You should turn in any
Mole Day proposals and/or complete the
extra credit with additional time.
 We’ll meet together at 2:35 pm to check
station answers and watch a video.
Diet Coke and Mentos
 We’ll choose three group proposals to
display.
 Include: description of active
ingredients and any “special” things
that you’ve done to affect the reaction
Frosty Flask
 Double replacement, endothermic reaction
 Simple, low stress option for those who are a
little nervous with geysers or explosions 8-)
 Solid barium hydroxide reacts with solid
ammonium nitrate in an endothermic
reaction. The reactants are absorbing energy
from the surroundings.
Elephant Toothpaste




Decomposition, exothermic reaction
Easy to explain
Easy to perform
Easy to add a little flair
 H2O2 --> H2 + O2 with KI catalyst
Flame-Thrower




Sounds scary, looks pretty wild
Easy to do
Easy to explain
Only if you LOVE fire