Name__________________________________________
The Mole Concept
I.
Review: Avogadro’s Number
a. Avogadro’s Number (symbol ___) is named in honor of Italian chemist
________________
b. It tells us the number of atoms in ________ of a substance
c. The value of Avogadro’s number is ________________
II.
Review: Mole
a. The mole (symbol ____):
III.
IV.
b. We define it as the amount of substance that contains ________________of particles
c. The individual particles can be atoms, molecules, formula units, etc.
i. 1 Mole= ________________
ii. Avogadro’s number =________________
iii. 1 Mole=________________
Mole Analogies
a. If 6.02x1023 atoms of hydrogen were laid side by side, the total length would be long
enough to circle the Earth 1,000,000 times
b. The mass of 6.02x1023 Olympic shot-put balls would equal the mass of the Earth
c. The volume of 6.02x1023 softballs would equal the volume of the Earth
Extra Credit Question: If $6.02x1023 earns 5% interest per year, how many dollars does the
account earn every nanosecond? (must show all work to receive credit)
V.
Mole Calculations: Nmoles
a. We can convert between the number of particles and the number of moles.
b. Example:
i. How many moles of Iodine are in 2.5x1023 molecules of I2?
VI.
Mole Calculations: molesN
1
a. We can convert between the number of moles and the number of particles.
b. Example:
i. How many molecules of chlorine are in 0.250 moles of the gas?
Homework 1
1. How many moles of CaCl2 do 2.41 x 1024 formula units represent?
2. How many moles of water do 6.02 x 1023 molecules represent?
3. How many moles of glucose do 1.2 x 1024 molecules represent?
4. Convert 3.01 x 1023 molecules of C2H6 to moles.
5. How many atoms do 2.0 moles of He represent?
6. If iodine is not in a person's diet, a thyroid condition called goitre develops. Iodized salt
is all that it takes to prevent this disfiguring condition. Calcium iodate, Ca(IO3)2, is added
to table salt to make iodized salt. How many atoms of iodine are in 0.500 moles of
Ca(IO3)2?
2
7. Barium sulphate, BaSO4, is given to patients as a thick slurry in flavoured water before Xrays are taken of the intestinal tract. The barium blocks the X-rays, and the tract
therefore casts a shadow that is seen on the x-ray film. How many atoms are in 0.568
mole of barium sulphate.
VII.
VIII.
Molar Mass
a. Molar mass:
b. For elements: the molar mass is equal to its ________________, which we find on the
periodic table
c. For compounds: the molar mass is equal to the ______of the ________________
________________that make it up
Molar mass examples
a. Find the molar mass of the following substances:
i. Silver metal
ii. Magnesium nitrate
iii. NH3
iv. Manganese metal
v. Strontium acetate
vi. Sulfur hexafluoride
IX.
Mole Calculations: gramsmol
a. We can convert between the mass of a substance and the number of moles.
3
b. Example
i. How many moles are in 87.8g of Pb?
X.
Mole Calculations: molgrams
a. We can convert between the mass of a substance and the number of moles.
b. Example
i. How many grams are in 3.2 moles of (NH4)3PO4 ?
Homework 2
1. Calculate the molar mass of the following
a. C3H8
e Na2CO3
b. NO2
f. (NH4)2B4O7
c. CH3OOH
g. Ca(C6H12NSO3)2
d. Ba(OH)2
h. (NH4)2O
2. How many moles does 45.0 grams of C6H12O6 represent?
3. How many moles do 22.0 grams of CO2 represent?
4. What is the mass of 5.0 moles of Ba(CN)2 ?
5. Ammonium sulphate, (NH4)2SO4, is a fertilizer used to supply both nitrogen and sulphur. How
many grams of ammonium sulphate are in 35.8 moles of (NH4)2SO4.
4
XI.
Mole Calculations: g  N
a. We can also convert between mass and the number of particles
b. Example:
i. How many molecules are present in 1.470g of O2 gas?
XII.
Mole Calculations: g  N
a. We can also convert between the number of particles and mass
b. Example:
i. What is the mass in grams of 2.01x1022 atoms of sulfur?
Homework 3
1. How much mass does 7.53 x 1022 molecules of CH4 represent?
2. What would be the mass of 2.41 x 1024 formula units of barium hydroxide?
3. What would be the mass of 1.20 x 1024 molecules of water?
4. How many formula units does 200.0 grams of calcium carbonate represent?
5. Ammonium carbonate,(NH4)2CO3, is used as a fertilizer and to manufacture explosives. How
many atoms of grams are in 665 grams of this substance?
5
XIII.
Percent composition
a. Percent composition :
b. Before we continue we need to discuss what percentages are.
c. Percent expresses the amount of a single quantity compared to the entire sample
XIV.
Calculating % composition
a. Calculate the percent composition for each element in H2O
b. Calculate the percent composition for each element in Trinitrotoluene (TNT), C7H5(NO2)3
Homework 4
Calculate the percent composition for each element in the following compounds
1. MgO
2. HgO
3. (NH4)2S
4. Sr(NO3)2
5. Na2S
6
XV.
Empirical Formula
a. In the late 1700’s chemists were very interested in ________________, especially those
with oxygen.
b. This was because chemists could determine the ________________ of a compound
after the reaction through the use of ________________________
c. Empirical formulas:
d. Glycine is an amino acid found in protein. An analysis of glycine gave the following data:
32.0% carbon, 6.7 % hydrogen, 18.7% nitrogen, and 42.6% oxygen. Calculate the
empirical formula for the amino acid. (Assume 100g sample)
e. Calculate the empirical formula for caffeine. An analysis of caffeine gave the following
data: 49.5% carbon, 5.15 % hydrogen, 28.9% nitrogen, and 16.5% oxygen. (Assume 100g
sample)
Homework 4
1. Show the correct empirical formula for each of the following compounds
a. C5H10
b. C6H8O6
c. Hg2F2
d. CO2
e. N2O4
f. C6H14
2. What is the empirical formula for a compound which contains 0.0134 g of iron, 0.00769 g of sulfur
and 0.0115 g of oxygen?
7
3. Find the empirical formula for a compound which contains 32.8% chromium and 67.2% chlorine.
4. NAME the compound which contains 0.463 g Tl (#81), 0.0544 g of carbon, 0.00685 g of hydrogen
and 0.0725 g oxygen by finding its empirical formula.
5. 300 grams of an organic sample which contains only carbon, hydrogen and oxygen is analyzed and
found to contain 145.946 grams of carbon, 24.3243 grams of hydrogen and the rest is oxygen. What
is the empirical formula for the compound?
XVI.
XVII.
Molecular Formulas
a. Molecular formulas :
b. Benzene, styrene and acetylene, while very ___________substances with very
__________ properties, all have the same empirical formula ____.
c. Because they are different compounds they must have different _________________
and therefore different ___________________________.
Calculating Molecular formulas
a. Acetylene: 26 g/mole
8
b. Benzene: 78 g/mole
c. Styrene: 104 g/mole
d. The empirical formula for fructose is CH2O. If the molar mass of fructose is 180g/mol,
find the molecular formula of fructose.
e. Ethylene dibromide was used as a grain pesticide until it was banned in 1983.
i. Find the empirical formula if the percent composition is 12.7% C, 2.1% H and
85.1% Br.
ii. If the molar mass is 180g/mol, find the molecular formula of ethylene
dibromide.
Homework 5
1. In a previous problem, the empirical formula of a compound of phosphorus and oxygen was found to
be P2O5. Experimentation shows that the molar mass of this compound is 283.89g. What is the
compounds molecular formula?
9
2. A sample with a formula mass of 34.00 amu is found to consist of 0.44g H and 6.92g O. Find its
molecular formula.
3. If 4.04g of N combine with 11.46g O to produce a compound with a formula mass of 108.0 amu, what
is the molecular formula of this compound?
4. The empirical formula for trichloroisocyanuric acid, the active ingredient in many household
bleaches, is OCNCl. The molar mass of this compound is 232.41g. What is the molecular formula of
trichloroisocyanuric acid.
XVIII.
Crime Scene Investigation: Case Profile
a. Victim Data:
i. Tony DeMoy,
ii. 45 year old,
iii. Organic Chemist/Researcher
iv. Severe osteoarthritis
b. Synopsis
i. several signs around the death site that suggest foul play.
ii. wife has proven alibi
iii. four possible causes of his untimely death suggested by his wife
c. Task
i. Identify who and what killed Tony DeMoy.
d. Autopsy Results: high levels of the compound ____________ were found. (You will gain
access to the name of the compound when you show your calculations.)
e. Crime Scene evidence:
i. An unlabeled drug bottle was found in the medicine cabinet of DeMoy's
bathroom. A 532.99 g sample of the drug was analyzed and found to contain
346.12 g C, 23.98 g H, 108.52 g O, and 54.36 g S. The molar mass of the
compound was found to be 314.38 g/mol. It may be a drug prescribed for
osteoarthritis. Coincidentally, DeMoy's arthritis has become so intolerable
within recent weeks that he's had to rely on the aid of a crutch for mobility.
Prolonged ingestion of this drug is thought to lead to heart attack. Demoy's
doctor, Finley Finch has a quiet reputation of prescribing dangerous drugs to
"dispose of" unwanted patients. Lately, DeMoy has been gaining more
recognition in the community due to his latest research on aromatic
hydrocarbons. Could Finch's jealousy be the cause of Tony DeMoy's death?
10
ii. Several of DeMoy's full or partial fingerprints were retrieved from a tipped cup
found near the crime scene. A faint almond scent was detected around the rim.
A 823.15 g liquid sample of the compound was found to contain 3.74% H,
44.43% C, and 51.83% N. The molar mass was determined to be ~27.03 g/mol.
A friend of DeMoy's noticed a disgruntled neighbor, Shay Lemarck,
uncharacteristically eager to provide refills. Could this be the answer?
iii. DeMoy's wife mentioned that the osteoarthritis had become so debilitating as
of late that he was "popping painkillers like candy". Certain painkillers are even
more dangerous in large quantities than others. One indication that this may be
the cause of death was a partially full acetaminophen bottle found on the scene.
Chemical analysis of one pill (1454.10 g) revealed 924.08 g C, 87.39 g H, 134.80 g
N, and 307.83 g O. The molar mass of the drug is known to be 151.18 g/mol.
Could it be that the crime scene is not a crime scene at all?
iv. DeMoy's latest and most brilliant research was on a specific type of aromatic
hydrocarbon. DeMoy, being a paranoid individual, wouldn't specify which one,
but a 453.28 g sample was shown to contain only carbon and hydrogen.
Hydrogen contributed 7.76 % of the total mass and the molar mass was
determined to be ~78.12 g/mol. The laboratory had a carefully regulated air
flow to prevent high-level inhalation. DeMoy periodically mentioned to his wife
that he suspected his lab partner, Kasey Hatterson, was altering the flow rates.
Curiously, without DeMoy, the published research could mean thousands of
dollars for Hatterson. With money as motive, could this solve the mystery?
v. When you have calculated the empirical and molecular formulas for each
scenario and identified each substance, you may access the autopsy report to
confirm the cause of death. Who, if anyone, killed Tony DeMoy?
vi. Provide a short description of what this compound is and what it is used for.
11