NAME ______________________________________
UNIT 4 (3): The Mole: Advanced Stoichiometry
I-IV) Moles and Basic Stoich
V) Advanced Stoichiometry
Sometimes, a chemist just needs to consult a map....
22.4Liters
22.4 Liters
bridging coefficients
1 mole
____grams
1 mole
6.02 x 1023
___grams
6.02 x 1023
molecules
formula units
atoms
molecules
formula units
atoms
The above mole map can represent the numeric relationships between any two substances of a
balanced chemical reaction.
**************************************************
A) When do you use the "double" mole map? The key to knowing when you need to use the double
mole map rests in whether you are given * a balanced reaction equation (one with coefficients)
and /or told to work between *two different substances
(as in one reactant & one product OR 2 reactants or 2 products)
or with Avogadro’s Hypothesis, Limiting Reagents etc…
B) Process
STEP 1 Read the problem & circle the important words and
STEP 2 Write your "desired" = givenunit
measurements
___
unit
STEP 3 Draw a mole map and fill-in each variable with the correct conversion factor& label start/finish
STEP 4
Solve the problem by manipulating conversion factors so that units cancel out.
1) Given:
C5H12(g) + 8 O2(g)  5 CO2(g) +
6 H2O(g)
Given the balanced equation, calculate the number of grams of carbon dioxide produced when
89.6 L of O2(g) are consumed completely.
Recall about the balanced equation:
1mole of C5H12(g) requires 8 moles of dioxygen gas to produce 
5 moles of carbon dioxide gas and 6 moles of water vapor
It is … in effect … the recipe ….
* Fruit Smoothie: 1.5 cups milk + 1.5 cups stawberry drink mix + 1 cup vanilla yogurt + 1 cup strawberries  4 cups of smoothie drink
249
2) Given: 2 Al(s) + 3 H2SO4(aq)  Al2(SO4)3(aq) + 3 H2(g)
Given the balanced equation, calculate the grams of dihydrogen gas produced, when
189 grams of aluminum are consumed completely in an ◊excess of sulfuric acid (H2SO4(aq))
◊
(we use the term “excess” to ensure that the reader understands that there is so much of the reactant, that the other reactant will
be consumed completely and be depleted first….leaving some of the “excess” reactant, unreacted, in the vessel)
3) Given:
O2(g) + 4 K(s)  2 K2O(s)
Calculate the liters of dioxygen gas at STP required to oxidize 150.0 grams of potassium
metal completely.
MOLE TO MOLE CONVERSIONS
(Fairly basic, fairly useless … it just gives molar relationships … it doesn’t deal with mass … This just helps to understand the use of
the coefficients as “bridging” two different substances.)
1) Given the balanced equation:
2 C2H6(g) +
7 O2(g) 
4 CO2(g) + 6 H2O(l)
How many moles of dioxygen (O2(g)) must be consumed in order to produce 2.0 moles of water?
7 O2 : 6 H2O
1 Mole O2
1 Mole H2O
bridging coefficients
moles of O2(g) = 2.0 moles of H2O |
|
moles of H2O
250
2) Given the balanced equation:
2 C7H14(g) + 21 O2(g)
 14 CO2(g) + 14 H2O(g)
How many moles of carbon dioxide are produced when 10.5 moles of dioxygen are consumed in an excess
of heptene (C7H14)?
1 Mole
1 Mole
bridging coefficients
moles of CO2 = 10.5 moles O2 |
|
moles O2
3) Given the balanced equation:
2 C8H14(g)
+ 23 O2(g)  14 H2O(g) + 16 CO2(g)
How many moles of C8H14 must be combusted in an excess of oxygen to produce 28.00 moles of water?
1 Mole
1 Mole
bridging coefficients
4) Given the balanced equation : 11 O2(g) + 2 C4H6(g)  8 CO2(g) + 6 H2O(l)
Calculate the moles of CO2 produced when 0.500 moles of C4H6 are combusted completely in an excess of
dioxygen.
ASSIGNMENT: Go to : http://tinyurl.com/264w5ek
Or http://chemunder.chemistry.ohio-state.edu/under/chemed/qbank/quiz/bank3.htm
Click on the 9th quiz (Stoichiometery Mole to Mole Problems) and take the quiz ... grade your results.
251
NAME ________________________________ NOTES: UNIT 4: MULTI-STEP MOLE CONVERSIONS
(This is Purely Honors Chemistry)
3 STEP CONVERSION PROBLEMS
___1. Given: 4 Al(s) + 3O2(g)  2 Al2O3(s)
How many grams of O2(g) (GFM=32 g), at STP are consumed completely in the production of 43.012 grams
of Al2O3(s) (GFM=102 g)
L
|
1 Mole
bridging coefficients
/ \
g. 6.02 x 1023
a) 20.241 grams
b) 9.4460 grams
L
|
1 Mole
/
\
g. 6.02 x 1023
c) 22.400 grams
d) 0.85203 grams
___2. Given: 4 BCl3 + P4 + 6 H2  4 BP + 12 HCl
Calculate the number of grams of BCl3 (GFM=116 g) required to react completely with 4.00 grams of
H2 gas (GFM= 2g) at STP, in an excess of tetraphosphorus (P4 or white phosphorus).
L
L
|
|
1 Mole
1 Mole
bridging coefficients
/ \
/
\
g. 6.02 x 1023
g. 6.02 x 1023
a) 91.5 g
b) 13.2 g
c) 155 g
d) 268 g
___ 3. Given: 2 Mg(s) + O2(g)  2MgO(s)
Calculate the number of grams of Mg (GAM=24 g) required to produce 100. grams of MgO (GFM = 40 g), in
an excess of dioxygen gas.
L
|
1 Mole
bridging coefficients
/ \
g. 6.02 x 1023
a) 75.0 g
b) 781 g
L
|
1 Mole
/
\
g. 6.02 x 1023
c) 9.00 g
d) 60.0 g
252
___4. Given:
C3H8(g) + 5 O2(g)  3 CO2(g) + 4 H2O(g)+ kJ
Assuming an excess of propane, calculate the volume of oxygen gas (GFM= 32g) required to produce 88.0 grams of
CO2gas (GFM= 44 g) at STP. (Think...you want volume …What UNIT will you need to use?))
L
|
1 Mole
bridging coefficients
/ \
g. 6.02 x 1023
a) 74.7 L
b) 62.8 L
L
|
1 Mole
/
\
g. 6.02 x 1023
c) 19.5 L
d) 21.2 L
___5. Given: F2(g) + 2KCl(aq) → 2KF(aq) +
Cl2(g)
Assuming an excess of KCl, calculate the number of grams of fluorine gas (GFM =38 g) required to produce
103.67 grams of dichlorine gas (GFM=70 g)
L
|
1 Mole
bridging coefficients
/ \
g. 6.02 x 1023
a) 64.115 g
b) 58.285 g
L
|
1 Mole
/
\
g. 6.02 x 1023
c) 56.278 g
d) 38.027 g
___ 6. Given: 2 KClO3(s) 
2 KCl(s) + 3 O2(g)
How many grams of KCl (GFM = 74 g) must also be produced, when 134.0 L of O2 (GFM=32 g) are produced, at STP?
L
|
1 Mole
bridging coefficients
/ \
g. 6.02 x 1023
a) 43.01 g
b) 295.1 g
L
|
1 Mole
/
\
g. 6.02 x 1023
c) 84.30 g
d) 110.2 g
253
___ 7. Given: Fe(s) + CuSO4(aq)  Cu(s) + FeSO4(aq)
Calculate the mass, in grams, of copper metal (GAM= 64 g) produced when 112.0 g of Fe (GAM = 56 g)
are reacted completely.
L
|
1 Mole
bridging coefficients
/ \
g. 6.02 x 1023
a) 57.10 g
b) 108.5 g
L
|
1 Mole
/
\
g. 6.02 x 1023
c) 52.28 g
d) 128.0 g
___8. Given: 2 Ca3(PO4)2(s) + 6 SiO2(s) + 10 C(s)  P4(s) + 6 CaSiO3(s) + 10 CO(g)
Calculate the number of molecules of tetraphosphorus (P4) produced when 892.43 grams of Ca3(PO4)2 are
consumed completely in excesses of the other reactants.
L
|
1 Mole
bridging coefficients
/ \
g. 6.02 x 1023
a)
b)
c)
d)
L
|
1 Mole
/
\
g. 6.02 x 1023
4.6620 x 1024 molecules
8.6652 x 1023 molecules
9.4016 x 1023 molecules
1.0262 x 1015 molecules
____9. Given
2 C8H18 + 15 O2  16 CO2 + 18 H2O
Calculate the mass, in kilograms, of CO2(g) produced when 114.0 grams of octane are combusted completely in
an excess of dioxygen gas. Recall: 1,000 grams = 1 kilogram
L
|
1 Mole
bridging coefficients
/ \
g. 6.02 x 1023
ANS. 1. a
L
|
1 Mole
/
\
g. 6.02 x 1023
a) 3.520 x 10-1 kg
c) 2.861 x 10-1 kg
b) 4.511 x 10-2 kg
d) 7.205 x 10-2 kg
2. c
3. d
4. a
5. c
6. b
7. d
8 b
9. a
ASSIGNMENT: Go to : http://tinyurl.com/264w5ek
Or http://chemunder.chemistry.ohio-state.edu/under/chemed/qbank/quiz/bank3.htm
Click on the 11th quiz (Mass-Mass Stoichiometry Problems) and take the quiz ... grade your results.
254
MIX IT ON UP!!!
1. GIVEN: 4 Al(s) + 3 O2(g)  2 Al2O3(s)
AT STP,how many mol of O2(g) (GFM=32g) are required to produce 0.500 mol of Al2O3(s) (GFM=102 g) ?
(Ans= 0.750 moles)
Draw a mole map
2. CHALLENGE : GIVEN: Fe3(PO4)2(aq) + 6 NaOH(aq) 
2 Na3PO4(aq) + 3 Fe(OH)2(s)
How many grams of NaOH (GFM=40) are required to produce 450. grams of Fe(OH)2 (GFM= 90 g)
(Ans = 400. g)
Draw a mole map
3. GIVEN:
2 Na(s) + Cl2(g) 
2 NaCl(s)
How many moles of NaCl are produced when 45.0 grams of Cl2 are reacted completely?
(Ans=1.29 moles)
Draw a mole map
255
4. GIVEN:
2 C8H18 + 15 O2  16 CO2 + 18 H2O
At STP how many liters of CO2 are produced when 342 grams of octane are combusted completely
in an excess of oxygen ?
(Ans= 538 liters)
Draw a mole map
5. GIVEN:
N2(g) + 3 H2(g)  2 NH3(g)
How many moles of hydrogen gas are required to react completely with 6.50 moles of nitrogen gas?
(Ans=19.5 moles)
Draw a mole map
6. GIVEN: 4 Fe(s) + 3 O2(g) + 6 H2O(l)  4 Fe(OH)3(s)
At STP, how many liters of O2 gas are required to produce 233.9 grams of Fe(OH)3 in an excess of iron?
(ans=36.72 L)
Draw a mole map
256
7. GIVEN: 2 PbO(s) + 2 SO2(g)  2 PbS(s)
+ 3O2(g)
In an excess of sulfur dioxide, calculate the moles of PbO required to produce, 1.55 mol of dioxygen gas at STP
(ans=1.03 moles)
Draw a mole map
8. GIVEN: 2 Fe2O3(s) + 3 C(s) 
4 Fe(s) + 3 CO2(g)
How many grams of Fe are produced when 49.3 grams of carbon dioxide gas are produced as well?
(ans= 83.7 grams)
Draw a mole map
257
NAME ________________________________ NOTES: UNIT 4: MULTI-STEP MOLE CONVERSIONS
I-V) advanced stoich.
VI) Avogadro’ Hypothesis: An Application of Mole Theory and Stoichiometry
1) Avogadro’s Hypothesis: Equal volumes of different gases have * equal numbers of molecules
___________________________ when compared to each other at the same temperature and pressure.
Translation: At the same conditions, equal volumes of gases have the same number of molecules.
Note:
Now, the temperature and pressure do NOT need to be STP, but for the purposes of the Regents course, we tend to use STP values.
BUT
# of molesgiven = # of molesselection
# of Litersgiven = # of Litersselection
# of moleculesgiven = # of moleculesselection
# of gramsgiven almost never equals # of gramsselection
1) This is based upon the idea that the number of molecules in 1 mol = 1 mol of anything else .
For gases, this assumes all samples are at the same temperature and pressure:
e.g 1)
11.2 L of H2(g) have the same number of molecules as 11.2 L of He(g)
e.g 2)
1.5 moles of H2(g) have the same number of molecules as 1.5 moles of He(g)
e g 3)
8.0 grams (or 4 .0 mol) of H2(g)
vs
16 grams (or 4.0 mol) of He(g)
assume temperature and pressures are the same for each
Compare their volumes: * They are equivalent
Compare their number of molecules: * They are equivalent
Compare the masses of the samples: * They are different, because each helium species is larger than
each hydrogen molecule.
Compare their densities: * They are different ... Due to the larger size of the helium species, there is
less empty space between the particles (the particles are more tightly packe4)
258
PRACTICE WITH AVOGADRO’S HYPOTHESIS: Using a double mole map with bridging coefficients of 1:1 may be
of serious value to you....
___1. Which of the following would occupy the same volume as 2.5 moles of H2(g) at STP?
(think: what equals 2.5 moles of any gaseous substance?)
1) 1.5 moles of He(g) at STP
3) 3.0 moles of He(g) at STP
2) 3.5 moles of He(g) at STP
4) 2.5 moles of He(g)
at STP
___2. The choices to question #1 could be worded in a slightly different manner:
Which of the following would occupy the same number of liters as 2.50 moles of H2(g) at STP
(THINK: When in doubt … convert to moles)
1)
2)
3)
4)
56.0 L of He(g) at STP
11.2 L of He(g) at STP
22.4 L of He(g) at STP
33.6 L of He(g) at STP
___3. Which of the following would occupy the same number of liters as 2.50 moles of H2(g) at STP
(Honors Level: When in doubt … convert to moles)
1)
2)
3)
4)
14.0 grams of He(g) at STP
12.0 grams of He(g) at STP
10.0 grams of He(g) at STP
6.00 grams of He(g) at STP
___4. Which sample has the same volume as 4.00 moles of H2(g) at STP?
1) 2.00 moles of He(g) at STP
2) 0.50 moles of He(g) at STP
3) 1.50 moles of He(g) at STP
4) 4.00 moles of He(g) at STP
259
___5. Which gas samples have the same number of molecules?
(Apply Avogadro’s Hypothesis: Equal volumes under the same conditions must have equal numbers of molecules….)
1) 1 Liter of H2(g) and
2 Liters of He(g) , each at STP
2) 1 Liter of H2(g) and 1 Liter of He(g) , each at STP
3) 0.5 Liter of H2(g) and 1 Liter of He(g) , each at STP
4) 1 Liter of H2(g)
and 0.5 Liter of He(g) , each at STP
___6. Which of the following would occupy the same volume as 1.50 moles of H2(g) at STP?
(Honors Level: When in doubt … convert to moles)
1) 10.0 g of Ne(g) at STP
2) 20.0 g of Ne(g) at STP
3) 30.0 g of Ne(g) at STP
4) 40.0 g of Ne(g) at STP
___7. Equal volumes of all gases at the same temperature and pressure contain an equal number of
1) atoms
2) electrons
3) compounds
4) molecules
___8. 1 liter of He(g) at STP should possess the same number of ________ as 1 liter of H2(g) at STP.
1) molecules
2) electrons
3) protons
4) atoms
___9. A sample of oxygen gas is sealed in container X. A sample of hydrogen gas is sealed in container
Z. Both samples have the same volume, temperature, and pressure. Which statement is true?
(1) Container X contains more gas molecules than container Z
(2) Container X contains fewer gas molecules than container Z
(3) Containers X and Z both contain the same number of gas molecules
(4) Containers X and Z both contain the same mass of gas.
260
___10. At the same temperature and pressure, which sample contains the same number of moles of
particles as 1 liter of O2(g)?
(1) 1 L Ne(g)
(2) 2 L N2(g)
(3) 0.5 L SO2(g)
(4) 1 L H2O(l)
___11) At 450 K and 1.75 atm., 1.0 liter of CO2(g) and 1.0 liter of NO2(g) have
(1) equal masses and the same number of molecules
(2) different masses and a different number of molecules
(3) equal volumes and the same number of molecules
(4) different volumes and a different number of molecules
12) Consider two different gases each with a total volume of 2.0 L, at 1.5 atm and 300. K.
Gas A has a density of 0.00862 g/L and Gas B has a density of 0.0178 g/L. Comment upon the relative size
of the individual gas molecules and distance between the gas molecules. Use terms like larger, smaller, greater, lesser …..
The size of individual molecules of Gas A is * smaller
relative to the size of the
molecules of Gas B. The distance (empty space) between the particles of Gas A is * greater
relative to the distances between the molecules of Gas B
Answers: 1) 4
2) 1 3) 3 4) 4 5) 2 6) 3 7) 4
8) 1
9) 3 (Note:due to differences in GAM, the masses are rarely equal)
10) 1 11) 3 masses are rarely equal, but the stem of the question, tells you that the volumes are equal (each is 1 L)
261
EXTRA, EXTRA on Avogadro’s Hypothesis ...For those who may wish it....
DIRECTIONS: Here is another worksheet for practicing Avogadro's Hypothesis and some simple 1 step
conversions. Answer each question by selecting the most correct choice. Answers are on the last page.
RECALL: When is comes to considering the implications of Avogadro’s Hypothesis, assuming identical
conditions of temperature and pressure of gaseous samples the:
BUT
# of molesgiven = # of molesselection
# of Litersgiven = # of Litersselection
# of moleculesgiven = # of moleculesselection
# of gramsgiven almost never equals # of gramsselection
1) Which of the following would occupy the same volume as 1.50 moles of O2(g) at STP ?
1)
2)
3)
4)
33.6 L of
78.4 L of
67.2 L of
56.0 L of
H2(g)
H2(g)
H2(g)
H2(g)
Think: You’re given moles. Each selection is
in Liters (a volume)
at STP
at STP
at STP
at STP
You have at least 2 options …
Convert the “given” moles to Liters or
Convert each selection to moles…
24
2. Which of the following would occupy the same volume as 1.806 X 10 molecules of NH3(g) at STP ?
1)
2)
3)
4)
22.4 L
67.2 L
11.2 L
5.6 L
of
of
of
of
He(g)
He(g)
He(g)
He(g)
at
at
at
at
STP
STP
STP
STP
Think: You’re given molecules. Each selection is
a volume
You have at least 2 options…
Convert the “given” moles to Liters or
Convert each selection to molecules…
3. Which of the following would occupy the same volume as 11.0 grams of CO2(g) at STP?
1)
2)
3)
4)
20.0 grams of Ne(g) at STP
10.0 grams of Ne(g) at STP
5.00 grams of Ne(g) at STP
40.0 grams of Ne(g) at STP
Think: You’re given a mass. Each selection is a mass
You have work to do….
Convert the “given” mass to moles &
Convert each selection mass to moles… compare
262
23
4. Which of the following would occupy the same volume as 1.505 x 10 molecules of He(g) at STP ?
Think: What have you been “given”?
1)
2)
3)
4)
7.000 grams of N2(g) at STP
8.000 grams of N2(g) at STP
84.00 grams of N2(g) at STP
1.000 gram of N2(g) at STP
What are the units of the selections?
5. Which of the following would occupy the same volume as 1.50 moles of oxygen gas at STP?
Think: What have you been “given”?
23
1) 1.51 x 10 molecules of Ne(g) at STP
23
2) 3.01 x 10 molecules of Ne(g) at STP
3) 6.02 x 10
What are the units of the selections?
23
molecules of Ne(g) at STP
4) 9.03 x 10 molecules of Ne(g) at STP
23
6. Which of the following equals the same number of moles as in 16.0 grams of SO2(g) at STP ?
1)
2)
3)
4)
1.00 gram of H2(g) at STP
2.00 grams of H2(g) at STP
0.500 gram of H2(g) at STP
4.00 grams of H2(g) at STP
23
7) Which of the following would occupy the same volume as 1.47 x 10 molecules of helium gas at STP?
1)
2)
3)
4)
1.00 mole of H2(g) at STP
2.05 mole of H2(g) at STP
0.198 mole of H2(g) at STP
0.244 mole of H2(g) at STP
8) Which of the following samples contains the same number of molecules as 81.8 L of H2(g) at STP ?
1)
2)
3)
4)
15.3 grams of He at STP
14.6 grams of He at STP
11.9 grams of He at STP
13.0 grams of He at STP
263
For questions 9-11, one or more of the responses given is (are) correct. Using your understanding of chemistry
decide which of the responses is (are) correct. Then choose :
1)
2)
3)
4)
5)
if only I is correct
if only II is correct
if only I and II are correct
if only II and III are correct
if I, II, and III are correct
___9) Which of the following masses of gases would occupy the same volume as 12.0 grams of He(g) at STP ?
I)
48.0 grams of O2(g) at STP
II) 132 grams of CO2(g) at STP
III)
6.00 grams of H2(g) at STP
___10) In theory, which of the following is (are) equal in volume to the volume occupied by
1.00 mole mass of H2(g) at STP ?
I)
22.4 L of He(g) at STP
II) 1.00 mole of Ne(g) at STP
III) 38.0 grams of F2(g) at STP
___11) Which of the following contain(s) the same number of molecules as 2.0 moles of SO2(g) at STP ?
I)
88 grams of CO2(g) at STP
II)
1.204 x 10 molecules of HCl(g) at STP
24
III) 11.2 L of O2(g) at STP
264
12) Assume equal sized containers of 22.4 liters.
1 mol of helium gas at STP has a mass of 4.00 grams, a volume of 22.4 L, 6.02 x 1023 species
and a density of 0.179 g/L.
1 mol of dihydrogen gas (or hydrogen gas) at STP has a mass of 2.00 grams a volume of 22.4 L,
6.02 x 1023 species, and a density of 0.0893 g/L
1) Why are the densities of the two gases so different from each other? ____________________
_______________________________________________________________________________
13) Avogadro’s Hypothesis has us infer, essentially, that 1 mol of a gas at the same conditions has the same
number of molecules as 1 mol of any other gas at identical conditions.
Assume 1.00 Liter of H2(g) at STP. How many molecules of gas are present?
Assume 1.00 Liter of He(g) at STP. How many molecules of gas are present?
ANSWERS:
1) 1 2) 2
3) 3
4) 1
5) 4
6) 3
7) 4
8) 2
9) 4 10) 5
11) 3
12) You could attack this arithmetically, by stating that density = mass/volume and use 1 mol mass and 22.4L as the values for the equation.
But I also like the idea that the densities are essentially different because they are compacted differently…. Gases will expand to fill the volume
of their container. However, a single hydrogen molecule is much smaller, compared to a single helium and thus, there must be a greater empty
space between the hydrogen molecules of the volume, assuming that the number of molecules is equal and the volumes occupied are equal….
13) 1 Liter is
or rather:
1 of a molar volume hence 1 Liter should have only 1
of 6.02 x 1023 molecules
22.4
22.4
molecules = 1.00 L | 6.02 x 1023 | =
22.4 L
2.69 x 1022 molecules
265