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WPHS
Chemistry
Unit 5 Packet
Stoichiometry
Bergmann-Sams
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Chemistry: Unit 5 Outline: Stoichiometry
Assignment
Must be done in class
Podcast 5.1
Worksheet 5.1
Lab: Simple Weight Loss

Podcast 5.2 (OPTIONAL/AS NEEDED)
Worksheet 5.2
Podcast 5.3
Worksheet 5.3

Lab: Vinegar—NaHCO3
Podcast 5.4
Worksheet 5.4
Lab: Limiting Reactant Exploration Lab
Lab: Limiting Reactant Lab


Podcast 5.5
Worksheet 5.5
Take Home Lab (Cookies-Optional)
Unit 5 Reviewsheet
Unit 5 Vocabulary
Lab Exam
Unit 5 Exam


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Unit 5: Vocabulary
Stoichiometry
Limiting reagent/limiting reactant
Excess reagent/excess reactant
Theoretical yield
Actual yield
Percent yield
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Representative
Particles of A
Representative
Particles of B
Stoichiometry Flowchart
Avogadro’s #
Avogadro’s #
Grams of B
Grams of A
Molar Mass
L of
Solution A
Molar Mass
The Land of The Mole
Molarity
Mole Ratio
Moles of A
22.4 L
L of gas A at
STP
Molarity
Moles of B
L of
Solution B
22.4 L
PV = nRT
PV = nRT
L of gas B at
STP
Gas B not at
STP
Gas A not at
STP
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(OPTIONAL) Take Home Lab: Making Chocolate Chip Cookies
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The following recipe for chocolate chip cookies recently appeared in Chemical & Engineering News (C&EN,
Jun 19, 1995, p. 100). It was attributed to Jeannene Ackerman of Witco Corp.
Ingredients:
1
2
3
4
5
6
7
8
9
10
587.5 cm3 gluten
4.9 cm3 NaHCO3
4.9 cm3 refined halite
176.25 cm3 partially hydrogenated tallow triglyceride
177.45 cm3 crystalline C12H22O11
177.45 cm3 unrefined C12H22O11
4.9 cm3 methyl ether of protocatechuic aldehyde
Two calcium carbonate-encapsulated avian albumen-coated protein
473.2 cm3 theobroma cacao
236.6 cm3 de-encapsulated legume meats (sieve size #10)
To a 2-L jacketed round reactor vessel (reactor #1) with an overall heat-transfer coefficient of about 100
Btu/F-ft2-hr add one, two, and three with constant agitation.
In a second 2-L reactor vessel with a radial flow impeller operating at 100 rpm add four, five, six, and seven
until the mixture is homogeneous.
To reactor #2 add eight followed by three equal portions of the homogeneous mixture in reactor #1.
Additionally, add nine and ten slowly with constant agitation. Care must be taken at this point in the reaction
to control any temperature rise that may be the result of an exothermic reaction.
Using a screw extrude attached to a #4 nodulizer place the mixture piece-meal on a 316SS sheet (300 x 600
mm). Heat in a 460K oven for a period of time that is in agreement with Frank & Johnston's first order rate
expression (see JACOS, 21, 55), or until golden brown.
Once the reaction is complete, place the sheet on a 25ºC heat-transfer table allowing the product to come to
equilibrium.
Conversion Factors
1 teaspoon = 5cm3
235 cm3 = 1 cup
ºC = 9/5ºF +32
To Receive Credit: You must have a signed note from your parent/guardian that indicates that you made the
cookies –you can even bring in a sample to your friendly Chemistry Teacher.
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PROBLEMS: Use dimensional analysis to set up the problem. Please show your work!
1. Show your work here for how much of each item you need to measure out at home:
2.
How many cookies did you made from this recipe?
3.
If you only have 100cm3 of unrefined C12H22O11, how much gluten will you need?
4.
You have decided with a group of friends to make these cookies for a fund raiser. It is your job to
make 1000 cookies. How many calcium carbonate-encapsulated avian albumen-coated protein will
you need to buy?
5.
Adjust the recipe for 3 calcium carbonate-encapsulated avian albumen-coated protein and determine
how much of each reactant you need in the recipe.
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STOICHIOMETRY LAB—Simple Weight Loss
A balanced equation indicates the proportions between reactants and products. More
specifically, the coefficients in the equation indicate the mole ratios between the chemical
substances. Thus, it is possible to determine how much product will be produced from a
given amount of reactant. This predicted amount can then be compared with the actual
amount produced to determine the percent yield of the reaction.
In this experiment, you will investigate two reactions:
1. Copper and aqueous silver nitrate yield silver and aqueous copper(II) nitrate.
2. Sodium bicarbonate and aqueous sulfuric acid produce aqueous sodium sulfate,
water, and carbon dioxide gas.
SAFETY

2M sulfuric acid can cause burns. Avoid skin and eye contact. Rinse spills with plenty of
water.
PROCEDURE
1. Obtain a beral pipet containing 2M H2SO4.
2. Obtain a clean, dry flask. Measure and record its mass.
Place approximately 0.30g of NaHCO3 into the flask.
Find the combined mass of the flask and sodium
bicarbonate and record.
3. Determine the exact mass of sodium bicarbonate by
subtraction. This mass must be between 0.20 and 0.40
g. Record the mass of sodium bicarbonate in a data
table.
4. Record the TOTAL mass of all the components of the
lab: sodium bicarbonate, flask, dropper and sulfuric
acid.
5. SLOWLY, drop by drop, add the sulfuric acid to the
sodium bicarbonate to generate carbon dioxide gas.
Continue releasing the acid in this manner until gas
production ceases.
6. Measure and record the TOTAL mass of all the
components again (like in step 4).
7. Return the beral pipet with the remainder of the sulfuric
acid. Rinse the contents of the flask down the drain
with water. Clean up your lab station.
DATA
Construct a data table for each reaction to display your laboratory measurements. Make sure that
each value is clearly labeled.
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ANALYSIS
1. Write a balanced equation for the reaction.
2. Calculate the actual mass of carbon dioxide produced (“actual yield”).
3. Using the balanced equation, calculate the mass of carbon dioxide that should be produced
from the mass of sodium bicarbonate that you used (“theoretical yield”).
CONCLUSIONS

Calculate the percent yield of the carbon dioxide using the equation below (show your work).
% yield =

experimental yield
theoretical yield
 100
A perfect percent yield would be 100%. Comment on your degree of accuracy and suggest
possible sources of measurement error. How could these errors be reduced in the future?
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Limiting Reactant Exploration Lab: How much Carbon Dioxide?
Introduction:
In this lab you will do a cool reaction, make some measurements, make a graph, and then
write down some observations. The reaction that you will do is the reaction between
vinegar and baking soda. In this reaction, carbon dioxide, CO2 will be produced. Chemists
use chemical symbols to show the reaction. The reaction is:
CH3COOH (aq)
Vinegar
+
NaHCO3
Baking
Soda

H2O
Water
+
Materials:
 Apparatus as pictured below
 Vinegar
 Baking Soda
To simplify: Here is a picture of what you will need:
Procedure:
Follow this procedure as closely as possible.
1. place 0.25 g into a paper towel
2. Get the appropriate amount of vinegar into the flask
3. Set-up the apparatus—and mix.
4. Record the amount of CO2 collected
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CO2
+
Carbon
Dioxide
NaCH3COO
Sodium
Acetate
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Data
Fill out the following data table:
Amount of vinegar
1
1 mL
Amount of baking
soda
0.25g
2
2 mL
0.25g
3
3 mL
0.25g
4
4 mL
0.25g
5
5 mL
0.25g
6
6 mL
0.25g
Vol CO2
HAVE YOUR TEACHER SIGN HERE IMMEDIATELY AFTER COLLECTING DATA
Questions
1. Describe in detail what occurred (your observations) when the vinegar was
mixed with the baking soda. Some descriptive words that you should probably
use are, but not including (gas given off, fizzing, foaming, balloon expanding)
2. Describe the pattern of how much carbon dioxide, CO2 was formed as you
added more and more vinegar. Relate this to the graph.
3. For each trial: explain which substance was the limiting and excess reagent.
Explain how you were able to determine this.
4. You should have noticed that as you increased the amount of vinegar eventually
you got the same amount of carbon dioxide, CO2. Explain why that occurred.
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Chemistry
Limiting Reactant Lab
Introduction
A limiting reactants is defined as one of the reactants in a chemical reaction that will be
used up first. The purpose of this lab is to determine the amount of precipitate that will be
produced when a given amount of calcium chloride and sodium sulfate are mixed.
Once you have massed the calcium chloride and the sodium sulfate you will need to do
each of the following before you proceed with the rest of the experiment.
 Write the balanced chemical reaction noting the states of matter for all substances.
(See solubility chart to determine which substance precipitates.)
 Determine which reagent, calcium chloride or sodium sulfate, is limiting.
 Predict the amount of the precipitate that will be produced.
Once you have done these three things, show them to your instructor. Then you may begin
the experiment.
Procedure
1.Label and mass a test tube. The test tube must be completely dry
2.Obtain about 0.30 grams of each reagent (It doesn’t matter how much you get just as
long as you know exactly how much you obtain), and determine both which reagent
is limiting and how much precipitate you will discover.
3.Dissolve the calcium chloride into 3 mL of deionized water by carefull flicking the test
tube (Your instructor will show you how to do this. Dissolve the sodium sulfate into
3-mL of deionized water.
4.Pour the sodium sulfate solution into the test tube with calcium chloride in it. Take
care to get all of the sodium sulfate into the calcium chloride test tube.
5.Remove the stopper and then place your sample into a centrifuge and spin out the
precipitate. (Caution should be used in using this device. Your teacher will instruct
you on proper use of a centrifuge)
6.Decant, or pour off, the liquid (supernatant) above the precipitate. Be careful not to
allow any of the precipitate to be poured out.
7.Add about 10-mL of deionized water to your precipitate and spin it again. Decant
again and repeat this step two more times for a total of four centrifuges
8.SHOW YOUR PRODUCT TO YOUR TEACHER AND GET HIS SIGNATURE. Set
your labeled test tube into a drying oven overnight.
9.Weigh your test tube and determine the mass of the precipitate that you have. SHOW
YOUR PRODUCT TO YOUR TEACHER AND GET HIS SIGNATURE AGAIN.
Compare this amount to what you expected to get from your calculations.
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Calculations
Show all calculations needed to determine the expected amount of precipitate
required to do the experiment. This should include the balanced chemical reaction and all
appropriate stoichiometric calculations.
Questions
1.Why did you have to mass the test tube prior to beginning the experiment?
2.Why did you need to add water to the solid calcium chloride and solid sodium
sulfate to cause the reaction to occur?
3.Comment on sources of error.
4.What was your percentage of error?
5.Draw a picture of the two test tubes prior to adding the two chemicals. What had
happened to the calcium chloride? What happened to the sodium sulfate.
6.Now draw a picture of the test tube once you have mixed the two chemicals. Where
are all of the chemicals now? Label this in your diagram.
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Worksheet 5.1 Stoichiometry
1. Carbon disulfide is an important industrial solvent. It is prepared by the reaction of
coke with sulfur dioxide:
5C(s) +
2SO2(g) -----> CS2(s)
+
4CO(g)
a. How many moles of CS2 form when 6.3 mol of C reacts?
b.
How many moles of carbon are needed to react with 7.24 moles of SO2
2. Silver can be made according to the following equation:
___AgNO3+ ___Ca  ___Ca(NO3)2 + ___Ag


Balance the equation
If 35.3 moles of silver nitrate are reacted how many moles of silver are
produced?
3. Barium oxide reacts with carbon dioxide to make Barium carbonate:
___BaO + ___CO2  ___BaCO3


Balance the equation
If 23.4 moles of barium oxide react, how many liters of CO2 are required at
STP?
4. Car batteries are called lead storage batteries because of their use of large quantities of
lead. These batteries utilize the following equation.
Pb + PbO2 +2H+ + 2HSO4-  2PbSO4 + 2 H2O

If 34.3-g of PbO2 react how many grams of water will be formed?

Assuming the same mass of PbO2, how many grams of PbSO4 will be formed?
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5. Ammonia, (NH3) is produced by reacting its elements with each other according to the
following equation:
___N2 + ___H2  ___NH3


Balance the equation.
If 34.3-L of nitrogen is reacted with hydrogen, how many liters at STP of
ammonia will be formed?
6. 32.5-g of ZnSO4 reacts to form how many grams of BaSO4 according to the following
equation. Don’t forget to balance the equation.
___ZnSO4 + ___BaCl2  ___BaSO4 + ___ZnCl2
7. When sodium metal is added to water the resulting gas, Hydrogen can often explode.
How many Liters of hydrogen gas is produced when 41.2-g of sodium is dropped into
water. Again, you must balance the equation in order to solve the problem.
___Na + ___HOH  ___NaOH + ___H2
8. Propane is a gas used often for backyard grills. How many Liters of CO2 is produced
when 54.9-L of propane (C3H8) is burned according to the following equation. Again, you
must balance the equation in order to solve the problem.
___C3H8 + ___O2  ___CO2 + ___H2O
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Worksheet 5.2 More Stoichiometry
1. How many moles of Carbon dioxide is formed when 44-mol of CH4 is burned?
2. 43.5-grams of barium sulfate is formed from the reaction of barium nitrate and
sodium sulfate. How many moles of sodium sulfate reacted?
3. 32.3-L of O2 is formed when KClO3 is decomposed. How many moles of KClO3
reacted initially?
__KClO3  __KCl + __O2
4. 22.8-g of NaOH is reacted with hydrochloric acid. How many grams of water is
formed?
5. 32.5-grams of iron III chloride reacts with silver nitrate. How many grams of silver
chloride are formed?
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6. 43.5-grams of copper II sulfate is reacted with barium nitrate. How many grams of
precipitate are formed?
7. How many liters of hydrogen gas is formed when 13.5-grams of calcium reacts with
sulfuric acid (H2SO4)?
8. Calculate the mass of silver needed to react with chlorine to produce 84 g of silver
chloride.
9. A volume of 7.5 L of hydrogen gas was produced from the single replacement
reaction of zinc and nitric acid (HNO3). Calculate the mass of zinc needed for this
reaction.
10. How many molecules of chlorine are needed to react with 5.6 g of iron to form iron
III chloride?
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Worksheet 5.3 Limiting Reactants
BOX ALL ANSWERS!!
1. When 114.0 g of iron and 292.7 g of chlorine gas reacts, iron(III) chloride is formed.
a. Write a balanced equation
b. How many grams of Iron (III) chloride is formed
c. What is the limiting reactant?
d. How much excess reagent is left over at the end of the experiment?
2. 20 L of oxygen react with 1.0L of methyl alcohol, CH3OH
a. Write a balanced equation
b How many liters of water will be formed at STP?
c. What is the limiting reactant?
d. How much excess reagent is left over at the end of the experiment?
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3. 25 g of hydrazine, N2H4(l), and 66 g of hydrogen peroxide, H2O2(l), react to produce
nitrogen gas and water.
a. Write a balanced equation
b. How many grams of nitrogen are produced?
c. What is the limiting reactant?
d. How much excess reagent is left over at the end of the experiment?
4. 22.5 grams of lithium reacts with 33.5 grams of aqueous aluminum sulfate. This is a
single replacement reaction.
a. Write a balanced equation.
b. How many grams of lithium sulfate will be formed?
c. What is the limiting reactant?
d. How much excess reagent is left over at the end of the experiment?
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5. 33.6 grams of sulfur dioxide reacts with 55.3 grams of water to form sulfurous acid
(H2SO3).
a. Write a balanced equation.
b. How many grams of sulfurous acid will be formed?
c. What is the limiting reactant?
d. How much excess reagent is left over at the end of the experiment?
6. 77 g of potassium iodide react with 32 g of lead II nitrate reacts to form a yellow
precipitate.
a. Write a balanced equation and identify the precipitate
b. How many grams of the precipitate will be formed?
c. What is the limiting reactant?
d. How much excess reagent is left over at the end of the experiment?
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Worksheet 5.4 Percent Yield
1. 15.5-g of NH4Cl reacts with an excess of AgNO3. In the reaction 35.5-g AgCl is
produced. NH4NO3 is the other product. What is the percent yield?
2. Potassium Chlorate decomposes according to the following reaction.
2KClO3  2KCl +3O2

In an experiment 32.5-g of KClO3 is decomposed and 15.2-g of KCl is formed.
What is the percent yield?
3. Nitrogen gas reacts with hydrogen gas to make ammonia (NH3). 15.5-L of N2 reacts at
STP to make 30-L of ammonia. What is the percent yield?
4. What is the percent yield of oxygen gas if 54L of O2 can be obtained from the
thermal decomposition of 500.0 g of potassium chlorate?
KClO3  KCl + O2
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5. It is desired to prepare 100.0g of silicon tetrafluoride by adding hydrogen fluoride to
silicon dioxide. The percent yield of this process is 75%. Ho much HF do you need to
react? The other product is water.
6. When black gunpowder explodes, potassium nitrate, carbon, and sulfur react with each
other to form nitrogen gas, carbon dioxide gas, and solid potassium sulfide. If the original
mixture contains 50.0 g of potassium nitrate, if the total volume of the gases is 20L, then
what is the percent yield for this process?
7. Very hot zinc will react with steam to form zinc oxide and hydrogen. 5.4L of H2 was
used to use up 20.0 g of zinc completely? What is the percent yield of this process?
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Worksheet 5.5 Molar Mass Worksheet
Name _________________
1. 2.35g of metal with a charge of +2 reacts with hydrochloric acid to produce 0.598 L
of gas at STP. What metal do you have?
M + HCl  MCl2 + H2
2. (NH4)3PO4 reacts with 0.0345 g of metal sulfate (M2(SO4)3) to produce 0.0399 g of
(NH4)2SO4. Balance the equation. What is the molar mass of the metal? What is
the metal?
__M2(SO4)3 + __(NH4)3PO4  __(NH4)2SO4 + __MPO4
3. 3.45g of a metal hydroxide with charge + 1 reacts with excess Iron III Chloride to
make 0.82g of Iron III hydroxide. What is the identity of the metal hydroxide?
4. 30.2 L of oxygen is produced at STP when 135.9 g of metal chlorate of charge +3
decomposes into oxygen and the metal chloride. What is the identity of the metal
chlorate?
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Unit 5 Reviewsheet
1. How many grams of water are formed when 12.5-g of hydrogen reacts with oxygen?
2. How many liters of carbon dioxide are formed when 12.3-g of sodium carbonate reacts
with 2.0-L of hydrogen chloride. The reaction is printed below:
___Na2CO3 + ___HCl  ___NaCl + ___H2O + ___CO2
3. How many grams of precipitate are formed when 24.3-g of zinc nitrate reacts with 20.5g of sodium phosphate?
4. How many liters of oxygen are produced when 3.25-g of KClO3 decomposes into KCl
and O2?
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5. When 2.25-g of sodium chloride reacts with excess silver nitrate, 3.45-g of precipitate is
formed. What is the percent yield of the precipitate?
6. 4.35-g of C5H12 reacts with 4.0-L of O2.
a. How many liters of CO2 are formed?
b. How much excess reactant remains?
7. 3.0-g of zinc reacts with silver nitrate to form how many grams of zinc nitrate?
8. 8.2-mol of barium carbonate decomposes into how many moles of barium oxide. The
other product is carbon dioxide.
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9. 4.5-g of sodium hydroxide reacts with 2.0-g of sulfuric acid (H2SO4). How many grams
of water are formed?
10. 8.0-L of butane (C4H10) reacts with oxygen to make 50-g of carbon dioxide. What is
the percent yield?
11. 8.5-L of hydrogen reacts with 5.4-L of nitrogen to make…
a. how many liters of ammonia (NH3)?
b. How many liters of excess reactant remains?
12.A 2.25-g sample of aluminum sulfate reacts with 3.25-g of sodium phosphate to make
1.0-g of precipitate. What is the percent yield?
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Stoichiometry Worksheet 1
KEY
1. Carbon disulfide is an important industrial solvent. It is prepared by the reaction of
coke with sulfur dioxide:
5C(s) +
2SO2(g) -----> CS2(s)
+
4CO(g)
 How many moles of CS2 form when 6.3 mol of C reacts?

How many moles of carbon are needed to react with 7.24 moles of SO2
6.3molC 1molCS2
x
 1.26molCS2
1
5molC
7.2molSO2 5molC
x
 18molC
1
2molSO2
2. Silver can be made according to the following equation:

2AgNO3+ Ca Ca(NO3)2 + 2Ag
35.3g
?g


Balance the equation
If 35.3 moles of silver nitrate are reacted how many moles of silver are produced?
5.3gAgNO3
2molAg
x
 35.3molAg
1
2molAgNO3
3. Barium oxide reacts with carbon dioxide to make Barium carbonate:
BaO + CO2 - BaCO3 (Balanced)
23.4mol


L?
Balance the equation
If 23.4 moles of barium oxide react, how many liters of CO2 are required at
STP?
23.4molBaO 1molCO2 22.4 LCO2
x
x
 524 LCO2
1
1molBaO 1molCO2
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4. Car batteries are called lead storage batteries because of their use of large quantities of
lead. These batteries utilize the following equation.
Pb + PbO2 +2H+ + 2HSO4- 2PbSO4 + 2
H2O
34.3g
g?


If 34.3-g of PbO2 react how many grams of water will be formed?
Assuming the same mass of PbO2, how many grams of PbSO4 will be formed?
34.3gPbO2 1molPbO2 2molH 2O 18gH 2O
x
x
x

1
239gPbO2 1molPbO2 1molH 2O
5.16gH 2O
34.3gPbO2 1molPbO2 2molPbSO4 303gPbSO4
x
x
x

1
239gPbO2 1molPbO2 1molPbSO4
87.0gPbSO4
5. Ammonia, (NH3) is produced by reacting its elements with each other according to the
following equation:

N2 + 3H2  2NH3
34.3L
L?


Balance the equation.
If 34.3-L of nitrogen is reacted with hydrogen, how many liters at STP of
ammonia will be formed?
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34.3LN2 2LNH3
x
 68.6LNH3
1
molN 2
6. 32.5-g of ZnSO4 reacts to form how many grams of BaSO4 according to the following
equation. Don’t forget to balance the equation.
ZnSO4 + BaCl2  BaSO4 + ZnCl2 bal
32.5g
g?


32.5gZnSO4 1molZnSO4 1molBaSO4 233gBaSO4
x
x
x

1
161gZnSO4 1molZnSO4 1molBaSO4
 47.0gBaSO4
7. When sodium metal is added to water the resulting gas, Hydrogen can often explode.
How many Liters of hydrogen gas is produced when 41.2-g of sodium is dropped into
water. Again, you must balance the equation in order to solve the problem.

2Na + 2HOH  2NaOH + H2
41.2g
L?
41.2gNa 1molNa 1molH 2 22.4LH2
x
x
x

1
23gNa 2molNa 1molH 2
 20.1LH2
8. Propane is a gas used often for backyard grills. How many Liters of CO2 is produced
when 54.9-L of propane (C3H8) is burned according to the following equation. Again, you
must balance the equation in order to solve the problem.

C3H8 + 5O2  3CO2 + 4H2O
54.9L
L?
54.9LC3 H8
3LCO2
x
165LCO2
1
1molC3 H8
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Stoichiometry WS B
Name
Period
1. How many moles of Carbon dioxide is formed when 44-mol of CH4 is burned?
CH 4  2O2  CO2  2 H 2O
44mol
?mol
44mol CH 4 1molCO2
x
 44molCO2
1
1molCH 4
+4
2. How many moles of calcium phosphate is formed when 32.5-mols of calcium nitrate
reacts with sodium phosphate?
3Ca(NO3 )2  2Na3 PO4  Ca3 (PO4 )2  6NaNO3
32.5mol
?mol
32.5mol Ca(NO3 )2 1molCa3 (PO4 ) 2
x
 10.8molCa3 (PO4 )2
1
3molCa(NO3 )2
3. 43.5-grams of barium sulfate is formed from the reaction of barium nitrate and sodium
sulfate. How many moles of sodium sulfate reacted?
Ba(NO3 )2  Na2 SO4  BaSO4  2NaNO3
?mol
43.5g
43.5gBaSO4 1molBaSO4 1molNa2 SO4
x
x
 0.187molNa2 SO4
1
233gBaSO4 1molBaSO4
4. 32.3-L of O2 is formed when KClO3 is decomposed. How many moles of KClO3
reacted initially?
2KClO3  2KCl  3O2
?mol
32.3L
32.3LO2 1molO2 2molKClO3
x
x
 0.961molKClO3
1
22.4LO2
3molO2
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5. 2.5-mol of water is made from its elements. How many particles of hydrogen reacted?
2H 2  O2  2H 2O
?part
2.5mol
2.5molH 2O 2molH 2 6.02x10 23 particlesH 2
x
x
1
2molH 2O
1molH 2
 1.5x10 24 particlesH 2
6. 22.8-g of NaOH is reacted with hydrochloric acid. How many grams of water is
formed?

NaOH  HCl  HOH  NaCl
22.8g
?g
22.8gNaOH 1molNaOH 1molHOH 18gHOH
x
x
x
1
40gNaOH 1molNaOH 1molHOH
 10.3gHOH
7. 32.5-grams of iron III chloride reacts with silver nitrate. How many grams of silver
chloride are formed?
FeCl3  3AgNO3  3AgCl  Fe(NO3 ) 3

32.5g
?g
32.5gFeCl3 1molFeCl3
3molAgCl 143.5gAgCl
x
x
x

1
162.5gFeCl3 1molFeCl3 1molAgCl
86.1gAgCl
8. 34.5-grams of Lithium reacts with Chromium III chloride. How many grams of lithium
 is formed?
chloride
3Li  CrCl3  3LiCl  Cr
34.5g
?g
34.5gLi 1molLi 3molLiCl 42.5gLiCl
x
x
x
 209gLiCl
1
7gLi
3molLi 1molLiCl
- 32 -
Name
9. 43.5-grams of copper II sulfate is reacted with barium nitrate. How many grams of
precipitate are formed?
CuSO4  Ba ( NO3 ) 2  BaSO4 ( s )  Cu( NO3 ) 2 ( aq)
43.5 g
g?
43.5gCuSO4 1molCuSO4 1molBaSO4 233gBaSO4
x
x
x

1
159.5 gCuSO4 1molCuSO4 1molBaSO4
63.5 gBaSO4
10 How many liters of hydrogen gas is formed when 13.5-grams of calcium reacts with
sulfuric acid?
Ca  H 2 SO4  CaSO4  H 2
13.5g
?L
13.5gCa 1molCa 1molH 2 22.4LH 2
x
x
x

1
40gCa 1molCa 1molH 2
7.6LH 2
11. 45.6-L of H2 is formed when zinc is reacted with nitric acid. How many grams of zinc
reacted?

Zn  2 HNO3  Zn( NO3 ) 2  H 2
?g
45.6L
45.6LH 2 1molH 2 1molZn 65 gZn
x
x
x

1
22.4 LH 2 1molH 2 1molZn
132 gZn
- 33 -
Name
12. 14.5-g of cesium explosively reacts with water to form hydrogen and cesium
hydroxide. How many molecules of hydrogen were formed?
2Cs  2 H 2O  2CsOH  H 2
14.5 g
?molec
14.5gCs 1molCs 1molH 2 6.02 x10 23 molecH 2
x
x
x

1
133 gCs 2molCs
1molH 2
3.28 x10 22 molecH 2
13. Calculate the mass of silver needed to react with chlorine to produce 84 g of silver
chloride.

2Ag
+
Cl2
2AgCl
?
84g
2Ag  Cl2  2AgCl
84gAgCl 1molAgCl
2molAg 108gAg
x
x
x
 63.2gAg
1
143.5gAgCl 2molAgCl 1molAg

14. A volume of 7.5 L of hydrogen gas was produced from the single replacement reaction
of zinc and nitric acid (HNO3). Calculate the mass of zinc needed for this reaction.

Zn
+
2HCl
ZnCl2
+
H2
g?
7.5L
7.5LH 2 1molH 2 1molZn 65 gZn
x
x
x

1
22.4 LH 2 1molH 2 1molZn
21.8 gZn
15. How many molecules of chlorine are needed to react with 5.6 g of iron to form iron III
chloride?

3Cl2
+
2Fe
2FeCl3
Molec?
5.6g
5.6gFe 1molFe 3molCl2 6.02x10 23 molecCl2
x
x
x

1
56gFe 2molFe
1molCl2
9.03x10 22 molecCl2

16. What mass of ammonia, NH3, is necessary to react with 2.1 x 1024 molecules of
oxygen when ammonia (NH3) reacts with oxygen to form water and nitrogen dioxide?
- 34 -
Name
4NH3
g?
+
7O2
2.1 x 1024 molec

4NO2 + 6H2O
2.1x10 24 molecO2
1molO2
4molNH3 17gNH3
x
x
x

1
6.02x10 23 molecO2 7molO2 1molNH3
33.9gNH3

17. Calculate the volume of carbon dioxide produced when 250 g of pentane, C5H12, burn.
Assume the carbon dioxide is cooled to STP.

C5H12
+
8O2
5CO2
+
6H2O
250g
?L
250gC5 H12 1molC5 H12 5molCO2 22.4LCO2
x
x
x

1
72gC5 H12 1molC5 H12 1molCO2
389LCO2

18. Nitrogen gas reacts with oxygen to form dinitrogen trioxide. How many molecules of
oxygen are needed to make 5.5 L of N2O3 at STP?

2N2
+
3O2
2N2O3
molec?
5.5L
23
2 3
2 3
2
5.5LN O 1molN O
3molO
6.02 x10 molecO2
x
x
x

1
22.4 LN 2O3 2molN 2O3
1molO2
2.2 x10 23 moleculesO2
19. Silver Nitrate reacts with sodium chloride to make the silver chloride and sodium
nitrate. When 2.53 grams of silver nitrate is reacted. How many grams of silver chloride
are formed?
AgNO3
+
NaCl
AgCl
+
NaNO3

2.53g
?g
2.53gAgNO3 1molAgNO3 1molAgCl 143.5gAgCl
x
x
x

1
170gAgNO3 1molAgNO3 1molAgCl
2.14gAgCl

- 35 -
Name
20. Methane (CH4) is burned in air. When 50.6 L of methane is burned how many grams
of carbon dioxide will be formed?
CH4
+
2O2
CO2
+
2H2O

50.6L
?g
50.6LCH4 1molCH4 1molCO2 44gCO2
x
x
x

1
22.4LCH4 1molCH4 1molCO2
99.4gCO2

21. Calcium Carbonate decomposes into calcium oxide and a common gas. When 45.5
grams of calcium oxide is formed how many liters of gas is also formed from this reaction.

CaCO3
CaO
+
CO2
45.5g
?L
45.5gCaO 1molCaO 1molCO2 22.4LCO2
x
x
x

1
56gCaO 1molCaO 1molCO2
18.2LCO2
22. When 3.25 g of copper II nitrate reacts with ammonium hydroxide. How many grams
of the precipitate will form.

Cu(NO3)2
+ 2NH4OH
Cu(OH)2 (s)
+ 2NH4NO3 (aq)
3.25g
?g=ppt

3.25gCu(NO3 ) 2 1molCu(NO3 ) 2 1molCu(OH) 2 97.5gCu(OH) 2
x
x
x

1
187.5gCu(NO3 ) 2 1molCu(NO3 ) 2 1molCu(OH) 2
1.69gCu(OH) 2
+88

- 36 -
Name
Limiting Reactant Worksheet
Do all work on a separate sheet of paper and
BOX ALL ANSWERS!!
1. When 114.0 g of iron and 292.7 g of chlorine gas reacts, iron(III) chloride is formed.
a. Write a balanced equation
b. What is the limiting reactant?
c. How many grams of Iron (III) chloride is formed
a. How much excess reagent is left over at the end of the experiment?
2Fe  3Cl2  2FeCl3
114g 292.7g
?g
114gFe 1molFe 2molFeCl3 162.5gFeCl3
x
x
x
 331gFeCl3
1
56gFe
2molFe
1molFeCl3
292.7gCl 2 1molCl 2 2molFeCl3 162.5gFeCl3
x
x
x
 447gFeCl3
1
71gCl 2
3molCl 2
1molFeCl3
Fe is the LR because it yielded the smallest answer
114gFe 1molFe 3molCl2 71gCl2
x
x
x
 217gCl2 used up
1
56gFe 2molFe 1molCl2
292.7  217g  75.9gCl2 left
2. 20 L of oxygen react with 1.0L of methyl alcohol, CH3OH
a. Write a balanced equation
b. What is the limiting reactant?
c How many liters of water will be formed at STP?
d. How much excess reagent will be left over?
2CH3OH  3O2  2CO2  4H2 O
1.0L
20L
?L
1.0LCH3 OH
4LH2 O
x
 2LH2 O
1
2LCH3 OH
20LO2 4LH2 O
x
 27LH2 O
1
3LO2
CH3OH is the LR because it yielded the smallest answer
1.0LCH3 OH
3LO2
x
 1.5LO2
1
2LCH3 OH
20L  1.5L  18.5LO2 Left
- 37 -
Name

3. 25 g of hydrazine, N2H4(l) and 66 g of hydrogen peroxide, H2O2 (l) react
exothermically to produce nitrogen gas and water.
a. Write a balanced equation
b. What is the limiting reactant?
c. How many grams of nitrogen are produced?
d. How much excess reagent is left over?
N2 H4  2H2 O2  N2  4H2 O
25g
66g
g?
25gN2 H4 1molN2 H4 1molN 2
28gN2
x
x
x
 22gN 2
1
32gN2 H4 1molN2 H4 1molN 2
66gH2 O2 1molH2 O2
1molN2
28gN2
x
x
x
 27gN2
1
34gH2O2 2molH2 O2 1molN2
N2 H4 is the LR because it yielded the smallest answer
25gN2 H4 1molN2 H4 2molH2 O2 34gH2 O2
x
x
x
 53gH2 O2
1
32gN2 H4 1molN2 H4 1molH2 O2
66g  53g  13gH2 O2 leftover
4. 22.5 grams of lithium reacts with a 33.5 grams of aqueous aluminum sulfate according
to a single replacement reaction.
a. Write a balanced equation.
b. What is the limiting reactant?
c. How many grams of lithium sulfate will be formed?
d. How much excess reagent will remain?
6Li  Al2 (SO4 )3  3Li2 SO4  2Al
22.5g
33.5
g?
22.5gLi 1molLi 3molLi2 SO4 110gLi2 SO4
x
x
x
 177gLi2 SO4
1
7g
6molLi
1molLi2 SO4
33.5gAl2 (SO4 ) 3 1molAl 2 (SO4 )3
3molLi2 SO4
110gLi2 SO4
x
x
x
 32gLi2 SO4
1
342gAl 2 (SO4 )3 1molAl2 (SO4 )3 1molLi2 SO4
Al2 (SO4 ) 3 is the LR since it yields the smaller value
33.5gAl2 (SO4 ) 3 1molAl 2 (SO4 )3
6molLi
7gLi
x
x
x
 4.1gLi
1
342gAl 2 (SO4 )3 1molAl2 (SO4 )3 1molLi
22g  4.1g  18gLiLeftover
- 38 -
Name
5. 33.6 grams of sulfur dioxide reacts with 55.3 grams of water to form sulfurous acid.
a. Write a balanced equation.
b. What is the limiting reactant?
c. How many grams of sulfurous acid will be formed?
d. How much excess reagent will remain?
SO2  H2 O  H2 SO3
33.6g 55.3g g?
33.6gSO2 1molSO2 1molH2 SO3 82gH2 SO3
x
x
x
 43gH2 SO3
1
64gSO2
1molSO2 1molH2 SO3
55.3gH2 O 1molH2 O 1molH2 SO3 82gH2 SO3
x
x
x
 252gH2 SO3
1
18gH2O
1molH2 O 1molH2 SO3
SO2 is the LR since it yields the smaller value
33.6gSO2 1molSO2 1molH2 O 18gH2 O
x
x
x
 9.5gH2 O
1
64gSO2 1molSO2 1molH2 O
55.3g  9.5g  45.8gH2 OLeftover
6. 77 g of potassium iodide react with 32 g of Lead II nitrate reacts to form a yellow
precipitate.
a. Write a balanced equation and identify the precipitate
b. What is the limiting reactant?
c. How many grams of the precipitate will be formed?
d. How much excess reagent will remain?
2KI  Pb(NO3 ) 2  PbI2  2KNO3
77g
32g
g?
77gKI 1molKI 1molPbI2 461gPbI2
x
x
x
 107gPbI2
1
166gKI 2molKI 1molPbI2
32gPb(NO3 )2 1molPb(NO3 )2
1molPbI 2
461gPbI2
x
x
x
 45gPbI2
1
331gPb(NO3 )2 1molPb(NO3 ) 2 1molPbI 2
Pb(NO3 ) 2 is the LR since it yields the smaller value
32gPb(NO3 )2 1molPb(NO3 )2
2molKI
166gKI
x
x
x
 32gKI
1
331gPb(NO3 )2 1molPb(NO3 ) 2 1molKI
77g  32g  45gKILeftover
- 39 -
Name
*7. In the following equation:
NH3 +
O2 --->
H2O +
NO2,
a. Balance the equation
b. What is the limiting reactant?
c. If you react 22 L of NH3 with 95 L of air (Which is 20% oxygen), how
many liters of NO2, will be produced?
d. How much excess reagent will remain?
4NH3  7O2  6H 2O  4NO2
22L
19L
L?
I got 19L of air by mulitplying 95L of air by 20%
22LNH3 4LNO2
x
 22LNO2
1
4LNH3
19LO2 4LNO2
x
 11LNO2
1
7LO2
O2 is the LR since it yields the smaller value
19LO2 4LNH3
x
 11LNH3
1
7LO2
22L 11L  11LNH3 Leftover

- 40 -
Name
WS D: Percent Yield Worksheet
1. 15.5-g of NH4Cl reacts with an excess of AgNO3. In the reaction 35.5-g AgCl is
produced. NH4NO3 is the other product. What is the percent yield?

NH4Cl
+
AgNO3
AgCl
+
NH4NO3
15.5g
35.5g
15.5gNH4 Cl 1molNH4 Cl 1molAgCl 143.5gAgCl
x
x
x

1
53.5gNH4 Cl 1molNH4 Cl 1molAgCl
41.57gAgCl
%
35.5g
x100  85.3%
41.57g
2. Potassium Chlorate decomposes according to the following reaction.
2KClO3  2KCl +3 O2
 In an experiment 32.5-g of KClO3 is decomposed and 15.2-g of KCl is formed.
What is the percent yield?

2KClO3
2KCl
+
3O2
32.5g
15.2g

32.5gKClO3 1molKClO3
2molKCl 74.5gKCl
x
x
x

1
122.5gKClO3 2molKClO3 1molKCl
 19.7gKCl
%
15.2g
x100  76.9%
19.7g

- 41 -
Name
3. Nitrogen gas reacts with hydrogen gas to make ammonia (NH3). 15.5-L of N2 reacts at
STP to make 30-L of ammonia. What is the percent yield?
N2
15.5L
+
3H2

2NH3
30L
15.5LN 2 2LNH3
x
 31LNH3
1
2LN 2
%

30L
x100  97%
31L
4. The Haber and Caude processes are methods by which ammonia (NH3) is synthesized
from its elements (H2 and N2) What is the percent yield if 5.0-kg of ammonia (in
Kilograms) is to be expected when 4000.0 L of nitrogen are used in these procedures?
N2 
3H 2  2NH3
4000L
5000g
4000LN 2 1molN 2 2molNH3 17gNH3
1kgNH3
x
x
x
x
 6.071kgNH3
1
22.4LN 2 1molN 2 1molNH3 1000gNH3
%

5.0kg
x100  82.3%
6.07kg
5. What is the percent yield of oxygen gas if 54L of O2 can be obtained from the thermal
decomposition of 500.0 g of potassium chlorate?
2KClO3  2KCl  3O2
500.0g
54L
500gKClO3 1molKClO3
3molO2
22.4LO2
x
x
x
 137LO2
1
122.5gKClO3 2molKClO3 1molO2
%
54L
x100  39.4%
137L

- 42 -
Name
6. It is desired to prepare 100.0g of silicon tetrafluoride by adding hydrogen fluoride to
silicon dioxide. The percent yield of this process is 75%. Ho much HF do you need to
react?
4 HF  SiO2  SiF4  2 H 2 O
?L
100.0g(75% )
100g
x

:: x  133gSiF4
75% 100%
133gSiF4 1molSiF4 4molHF 22.4 LHF
x
x
x
 114.6 LHF
1
104 gSiF4 1molSiF4 1molHF
7. When black gunpowder explodes, potassium nitrate, carbon, and sulfur react with each
other to form nitrogen, carbon dioxide, and potassium sulfide. If the original mixture
contains 50.0 g of potassium nitrate, if the total volume of the gases is 20L, what is the
percent yield for this process?
2 KNO3  3C  S  N 2  3CO2  K 2 S
50g
total vol of gases which are N 2 andCO2
50 gKNO3 1molKNO3 4mo lg ases 22.4 Lgases
x
x
x
 22.2 Lgases
1
101gKNO3 2molKNO3 1mo lg ases
%
20 L
x100  90.0%
22.2 L
8. Very hot zinc will react with steam to form zinc oxide and hydrogen. 5.4L of H2 was
used to use up 20.0 g of zinc completely? What is the percent yield of this process?
Zn  H 2O  ZnO  H 2
20g
?L
20gZn 1molZn 1molH 2 22.4Lgases
x
x
x
 6.9LH 2
1
65gZn 1molZn
1molH 2
5.4L
x100  78.3%
6.9L

- 43 -
Name
WS E Molar Mass Worksheet
1.
KEY
Name _________________
2.35g of metal with a charge of +2 reacts with hydrochloric acid to produce 0.598
L of gas at STP. What metal do you have?
M  2 HCl  H 2  MCl2
2.35 g............0.598L
grams 2.35 g

mol
mol ?
0.598LMH 2 1molH 2 1molM
x
x
 0.0267molM
1
22.4 LH 2 1molH 2
MM 
grams
2.35 g

 88 g / mol
mol
0.0266mol
Strontium
2. (NH4)3PO4 reacts with 0.0345 g of metal sulfate (M2(SO4)3) to produce 0.0399 g of
(NH4)2SO4. Balance the equation. What is the molar mass of the metal? What is
the metal?
__M2(SO4)3 + 2(NH4)3PO4  3(NH4)2SO4 + 2MPO4
0.0345g
0.0456g
MM 
g
0.0345 g

:: FindMoles
mol
mol
0.0399 g ( NH 4 ) 2 SO4 1mol ( NH 4 ) 2 SO4
1molM 2 ( SO4 )3
x
x
 1.00757 x10 4 molM 2 ( SO4 )3
1
132 g ( NH 4 ) 2 SO4 4 3mol ( NH 4 ) 2 SO4
MM 
MM 
g
0.0345 g
0.0345 gM 2 ( SO4 )3


 342 g / mol  M 2 ( SO4 )3
mol
mol
1.00757 x10 4 molM 2 ( SO4 )3
2M  (32 x3  16 x12)  342
M  27 g / mol  Alu min um ::: mustHave  3Ch arg e( HasToBeAMe tal )
- 44 -
Name
3. 3.45g of a metal hydroxide with charge + 1 reacts with excess Iron III Chloride to
make 0.82g of Iron III hydroxide. What is the identity of the metal hydroxide?
3MOH  FeCl3  Fe(OH ) 3  3MCl
3.45 g ......................0.82 g
grams 3.45 g

mol
mol ?
1
molFe
(OH ) 3 2
0.82 gMOH
3molMOH
x
x
 0.0230molMOH
1
107 gFe(OH ) 3 1molFe(OH ) 3
MM 
grams
3.45 g

 150 g / mol
mol
0.0230mol
MOH  36 g / mol
MM 
M  17  150
MM  133  Cs
4. 30.2L of oxygen is produced at STP when 135.9 g of metal chlorate of charge +3
decomposes into oxygen and the metal chloride. What is the identity of the metal
chlorate?

2 M (ClO3 ) 3 

2 MCl  9O2
135.9 g
30.2L
30.2O2 1molO2 2molM (ClO3 ) 3
x
x
 0.299molM (ClO3 ) 3
1
22.4 LO2
9molO2
MM 
135.9 gM (ClO3 ) 3
grams

 303 g / mol
mol
0.299molM (ClO3 ) 3
g
M (ClO3 ) 3  454 mol
M  (35.5 x3  16 x9)  454
M  250  454
M  204 g / mol  Tl
- 45 -
Name
Mixed Stoichiometry Worksheet KEY
1. How many grams of water are formed when 12.5-g of hydrogen reacts with oxygen?

2H2
+
O2
2H2O
12.5g
?g
12.5gH 2 1molH2 2molH 2O 18gH 2O
x
x
x

1
2gH 2
2molH 2 1molH 2O
 112.5gH 2O

2. How many liters of carbon dioxide are formed when 12.3-g of sodium carbonate reacts
with 2.0-L of hydrogen chloride. The reaction is printed below:
Na2CO3 + HCl  NaCl + H2O + CO2

Na2CO3
+
2HCl
2NaCl
+ H2 O
+ CO2
12.3g
2.0L
L?
12.3gNa2CO3 1molNa2CO3
1molCO2
22.4LCO2
x
x
x

1
106Na2CO3 1molNa2CO3 1molCO2
 2.60LCO2
2.0LHCl 1LCO2
x
 1.0LCO2
1
2LHCl
 1.0LCO2 : Answer because it is the lowest

3. How many grams of precipitate are formed when 24.3-g of zinc nitratre reacts with
20.5-g of sodium phosphate?

3Zn(NO3)2
+
2Na3PO4
Zn3(PO4)2
+
6NaNO3
24.3g
20.5g
?g (ppt)
24.3gZn(NO3 ) 2 1molZn(NO3 ) 2 1molZn 3 (PO4 ) 2 385gZn3 (PO4 ) 2
x
x
x

1
189gZn(NO3 ) 2 3molZn(NO3 ) 2 1molZn3 (PO4 ) 2
 16.5gZn3 (PO4 ) 2 :: This is the answer b/c it is lowest
20.5gNa3 PO4 1molNa3 PO4 2molNa3 PO4 385gZn3 (PO4 ) 2
x
x
x

1
164gNa3 PO4 3molZn(NO3 ) 2 1molZn3 (PO4 ) 2
 32.1gZn3 (PO4 ) 2

- 46 -
Name
4. How many liters of oxygen are produced when 3.25-g of KClO3 decomposes into KCl
and O2?

2KClO3
2KCl
+
3O2
3.25g
L?
3.25gKClO3 1molKClO3
3molO2
22.4LO2
x
x
x

1
122.5gKClO3 2molKClO3 1molO2
 0.89LO2
5. When 2.25-g of sodium chloride reacts with excess silver nitrate, 3.45-g of precipitate is
formed. What is the percent yield?

NaCl
+
AgNO3
AgCl
+
NaNO3
2.25g
3.45g

2.25gNacl 1molNaCl 1molAgCl 143.5gAgCl
x
x
x

1
58.5gNaCl 1molNaCl 1molAgCl
 5.51gAgCl
&Yield 
Actual
3.45g

x100  63%
Theoretical 5.51g
6. 4.35-g of C5H12 reacts with 4.0-L of O2.
a. How many liters of CO2 are formed?
b. How much excess reactant remains?

C5H12
+
8O2
4.35g
4.0L

4.35gC5 H12 1molC5 H12 5molCO2 22.4LCO2
x
x
x

1
72gC5 H12 1molC5 H12 1molCO2
6.76LCO2
4.0LO2 1molO2 5molCO2 22.4LCO2
x
x
x

1
22.4LO2 8molO2
1molCO2
 2.5LCO2 Answer due to being lower
4.0LO2 1molO2 1molC5 H12 72gC5 H12
x
x
x

1
22.4LO2
8molO2 1molC5 H12
 1.61gC5 H12 used up
4.35g 1.61g  2.74gC5 H12leftOver

- 47 -
5CO2
L?
+
6H2O
Name
7. 3.0-g of zinc reacts with silver nitrate to form how many grams of zinc nitrate?

Zn
+
2AgNO3
Zn(NO3)2
+
2Ag
3.0g
?grams?
3.0gZn 1molZn 1molZn(NO3 ) 2 189gZn(NO3 ) 2
x
x
x

1
65gZn
1molZn
1molZn(NO3 ) 2
 8.72gZn(NO3 ) 2
8. 8.2-mol of barium carbonate decomposes into how many moles of barium oxide. The
other product is carbon dioxide.

BaCO3
BaO
+
CO2
8.2mol
?mol

8.2molBaCO3 1molBaO
x
 8.2molBaO
1
1molBaCO3
9. 4.5-g of sodium hydroxide reacts with 2.0-g of sulfuric acid (H2SO4). How many grams
of water are formed?

2NaOH
+
H2SO4
2HOH
+
Na2SO4
4.5g
2.0g
G?
4.5gNaOH 1molNaOH 2molHOH 18gHOH
x
x
x

1
40gNaOH 2molNaOH 1molHOH
 2.0gHOH

2.0gH 2 SO4 1molH 2 SO4 2molHOH 18gHOH
x
x

1
98gH 2 SO4 1molH 2 SO4 1molHOH
 0.73gHOH this is the correct answer : It is lower

10. 8.0-L of butane (C4H10) reacts with oxygen to make 50-g of carbon dioxide. What is
the percent yield?

2C4H10
+
13O2
8CO2
+
10H2O
8.0L
50g
8.0LC4 H10 1molC4 H10
8molCO2
44gCO2
x
x
x

1
22.4LC4 H10 2molC4 H10 1molCO2
 62.8gCO2 : Theoretical
%Yield 

Actual
50.0

 79.5%
Theoretical 62.8
- 48 -
Name
11. 8.5-L of hydrogen reacts with 5.4-L of nitrogen to make…
a. how many liters of ammonia (NH3)?
b. How many liters of excess reactant remains?

3H2
+
1N2
8.5L
5.4L
2NH3
?L
8.5LH 2 2 LNH 3
x
 5.7 LNH 3 : Answer  lower
1
3molH 2
5.4 LN 2 2 LNH 3
x
 10.8LNH 3
1
1LN 2
8.5LH 2 1LN 2
x
 2.83LN 2UsedUp
1
3LH 2
5.4  2.8  2.6 L left over
12. ** 2.25-g of aluminum sulfate reacts with 3.25-g of sodium phosphate to make 1.0-g
of precipitate. What is the percent yield?

Al2(SO4)3
+ 2Na3PO4
2AlPO4
+ 3Na2SO4
2.25g
3.25g
1.0g
This is both a limiting reactant problem and a percent yield problem
2.25gAl2 (SO4 ) 3 1molAl2 (SO4 ) 3
2molAlPO4
122gAlPO4
x
x
x

1
339gAl2 (SO4 ) 3 1molAl2 (SO4 ) 3 1molAlPO4
 1.62gAlPO4 :: this is the theoretical amount due to being smaller
3.25gNa3 PO4 1molNa3 PO4 2molAlPO4 122gAlPO4
x
x
x

1
164gNa3 PO4 2molAlPO4 1molAlPO4
 2.41gAlPO4
%Yield 
Actual
1.0

x100  61.7%
Theoretical 1.62

- 49 -
Name
Chapter 10 Review
EHS Chemistry
1. 23.5-g of KClO3 decomposes in the following way:
KClO3  KCl + O2
How many grams of O2 was forms? (Make sure to balance the equation)
2. In the reaction:
Na2CO3 + H3PO4  Na3PO4 + H2O + CO2
How many grams of Na2CO3 react with the H3PO4 to produce 100L of CO2 at STP?
3. Mercury (II) oxide decomposes to form liquid mercury and oxygen gas. If 5.4 g of
mercury (II) oxide decomposes, how many grams of mercury is formed? (Hint: You must
start with a correctly balanced chemical reaction)
4. 2.5-g of C4H10 reacts with 0.59-L of O2 at STP to form CO2 and H2O.
a. Write the balanced equation.
b. How many grams of H2O will be formed?
c. How much excess reactant remains?
5. 2.30-g of Barium chloride reacts with 5.45-g of sodium carbonate in a double
displacement reaction. How many grams of precipitate will form? (Hint: These are the
calculations for the lab that you did). Make sure to use the table of solubilites to determine
which substance is the solid precipitate.
6. 32.5-g of Hg(NO3)2 reacts with NH4Cl to make HgCl2 and NH4NO3. When the
chemicals were mixed it was discovered that 20.0-g of HgCl2 was formed. What is the
percent yield?
7. BONUS: 2.52x1025 atoms of sodium react with 325-L of phosphoric acid gas (H3PO4)
at STP. 302.5-L of a gas is given off. What is the percent yield of the reaction?
- 50 -
Name
Chapter 10 Review KEY
EHS Chemistry
1. 23.5-g of KClO3 decomposes in the following way:
KClO3  KCl + O2
How many grams of O2 was forms? (Make sure to balance the equation)
2KClO3 
23.5g
2KCl
+
3O2
G?
23.5gKClO3 1molKClO3
3molO2
32gO2
x
x
x
1
122.5gKClO3 2molKClO3 1molO2
 9.2gO2

2. In the reaction:
Na2CO3 + H3PO4  Na3PO4 + H2O + CO2
How many grams of Na2CO3 react with the H3PO4 to produce 100L of CO2 at STP?
3Na2CO3 + 2H3PO4  2Na3PO4 + 3HOH + 3CO2
?g
100L
100LCO2 1molCO2 3molNa2CO3 106gNa2CO3
x
x
x

1
22.4LCO2
3molCO2
1molNa2CO3
 473gNa2CO3

3. Mercury (II) oxide decomposes to form liquid mercury and oxygen gas. If 5.4 g of
mercury (II) oxide decomposes, how many grams of mercury is formed? (Hint: You must
start with a correctly balanced chemical reaction)
2HgO
5.4g

2Hg
?g
- 51 -
+
O2
Name
5.4gHgO 1molHgO 2molHg 201gHg
x
x
x

1
217gHgO 2molHgO 1molHg
 5.0gHg

- 52 -
Name
4. 2.5-g of C4H10 reacts with 0.59-L of O2 at STP to form CO2 and H2O.
a. Write the balanced equation.
b. How many grams of H2O will be formed?
c. How much excess reactant remains?
2C4H10 +
2.5g
13O2 
0.59L
8CO2 + 10H2O
?g
2.5gC4 H10 1molC4 H10 10molH 2O 18gH 2O

x
x
x
58gC4 H10 2molC4 H10 1molH 2O
1
 3.88gH 2O
0.59LO2 1molO2 10molH 2O 18gH 2O

x
x
x
22.4LO2 13molO2 1molH 2O
1
 0.364gH 2O : LowestAnswer  correct
0.59LO2 1molO2 2molC4 H10 58gC4 H10
 0.24gC4 H10
x
x
x
22.4LO2 13molO2 1molC4 H10
1
2.5  0.24  2.26gC4 H10LeftOver

5. 2.30-g of Barium chloride reacts with 5.45-g of sodium carbonate in a double
displacement reaction. How many grams of precipitate will form? (Hint: These are the
calculations for the lab that you did). Make sure to use the table of solubilites to determine
which substance is the solid precipitate.
BaCl2 +
2.30g
Na2CO3 
5.45g
- 53 -
BaCO3 +
?g:ppt
2NaCl
Name
2.30gBaCl2 1molBaCl2 1molBaCO3 197gBaCO3
x
x
x

1
208gBaCl2 1molBaCl2 1molBaCO3
 2.18gBaCO3 ::: Correct  Lowest
5.45gNa2CO3 1molNa2CO3 1molBaCO3 197gBaCO3
x
x
x

1
106gNa2CO3 1molNa2CO3 1molBaCO3
 10.1gBaCO3

6. 32.5-g of Hg(NO3)2 reacts with NH4Cl to make HgCl2 and NH4NO3. When the
chemicals were mixed it was discovered that 20.0-g of HgCl2 was formed. What is the
percent yield?
Hg(NO3) + 2NH4C  HgCl + 2NH4NO
l
2
2
3
32.5g
20.0g
32.5gHg(NO3 ) 2 1molHg(NO3 ) 2
1molHgCl2
272gHgCl2
x
x
x

1
325gHg(NO3 ) 2 1molHg(NO3 ) 2 1molHgCl2
 27.2gHgCl2    Theoretical
%Yield 

Actual
20.0g

x100  73.5%
Theoretical 27.2g
7. BONUS: 2.52x1025 atoms of sodium react with 325-L of phosphoric acid gas (H3PO4)
at STP. 302.5-L of a gas is given off. What is the percent yield of the reaction?
6Na
+ 2H3PO4 
2.52E25
325L
- 54 -
2Na3PO4 + 3H2
302.5L
Name
2.52x10 25 atomsNa
1molNa
3molH 2 22.4LH 2
x
x
x

1
6.02x10 23 atomsNa 6molNa 1molH 2
 468.5LH 2
325LH 3 PO4
3LH 2
x
 487.5LH 2 :: LR due to lowest = theo
1
2LH 3 PO4
%Yield =
actual
302.5L

x100  64.5%
theoretcial 468.5L

- 55 -
Name
WS E Molar Mass Worksheet
_________________
1.
KEY
Name
(NH4)3PO4 reacts with 0.0345 g of metal sulfate (M2(SO4)3) to produce 0.0456 g of
(NH4)2SO4. Balance the equation. What is the molar mass of the metal? What is
the metal?
__M2(SO4)3 + 2(NH4)3PO4  3(NH4)2SO4 + 2MPO4
0.0345g
0.0456g
g
0.0345 g

:: FindMoles
mol
mol
1molM 2 ( SO4 ) 3
0.0456 g ( NH 4 ) 2 SO4 1mol ( NH 4 ) 2 SO4
x
x
 0.000115molM 2 ( SO4 ) 3
1
132 g ( NH 4 ) 2 SO4 4 3mol ( NH 4 ) 2 SO4
MM 
MM 
0.00345 gM 2 ( SO4 ) 3
g
0.0345 g


 299.6 g / mol  M 2 ( SO4 ) 3
mol
mol
0.000115molM 2 ( SO4 ) 3
2 M  (32 x3  16 x12)  300
M  6 g / mol  Li ::: CloseEnoughToLi ( HasToBeAMe tal )
2.
2.35g of metal with a charge of +2 reacts with hydrochloric acid to produce 0.598
L of gas at STP. What metal do you have?
M  2 HCl  H 2  MCl 2
2.35 g............0.598L
grams 2.35 g

mol
mol ?
0.598LMCl 2 1molH 2 1molM
x
x
 0.0267molM
1
22.4 LH 2 1molH 2
MM 
grams
2.35 g

 88 g / mol
mol
0.0266mol
Strontium
MM 
- 56 -
Name
3. 3.45g of a metal hydroxide with charge + 1 reacts with excess Iron III Chloride to
make 0.82g of Iron III hydroxide. What is the identity of the metal hydroxide?
3MOH  FeCl3  Fe(OH ) 3  3MCl
3.45 g ......................0.82 g
grams 3.45 g

mol
mol ?
1
molFe
(OH ) 3 2
0.82 gMOH
3molMOH
x
x
 0.0230molMOH
1
107 gFe(OH ) 3 1molFe(OH ) 3
MM 
grams
3.45 g

 150 g / mol
mol
0.0230mol
MOH  36 g / mol
MM 
M  17  150
MM  133  Cs
4. 30.2L of oxygen is produced at STP when 135.9 g of metal chlorate of charge +3
decomposes into oxygen and the metal chlorate. What is the identity of the metal
chloride?

3M (ClO3 ) 3 

3MCl  9O2
135.9 g
30.2L
30.2O2 1molO2 3molM (ClO3 ) 3
x
x
 0.449molM (ClO3 ) 3
1
22.4 LO2
9molO2
MM 
135.9 gM (ClO3 ) 3
grams

 303g / mol
mol
0.449molM (ClO3 ) 3
M (ClO3 ) 3  303
M  (35.5 x3  16 x9)  303
M  250  303
M  52 g / mol  Cr
- 57 -