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					                  Stoichy-what?! (Now you’re just making stuff up!)

The word stoichiometry comes from two Greek words: stoicheion (meaning "element") and metron
(meaning "measure"). Stoichiometry deals with calculations about the masses (sometimes
volumes) of reactants and products involved in a chemical reaction. It is a very mathematical
part of chemistry, so be prepared to use your calculator!

What You Should Expect
The most common stoichiometric problem will give you with a certain amount of a reactant
then ask how much of a product can be formed. Here is a generic chemical equation:

                                             2 A + 2B  3C

A typically-worded problem looks like this: Given 20.0 grams of A and sufficient B, how many
grams of C can be produced?” (Let’s solve it together!)

You will need to use naming, mole ratios, molar masses, balancing and interpreting chemical
equations, and converting between mass, volume, or “representative particles” and moles. If you
struggled with those in concepts last unit, welcome to the club (this stuff is not easy). Go back
and review what you need to, because if you can't do that stuff, sadly you can't do stoichiometry.

The Steps Involved in Solving Full-Blown Stoichiometry Problems
    1. Make sure your chemical equation is correctly balanced.
    2. Use the correct conversion factor to convert the “given” to moles (for grams use molar
       mass, for volume use 22.4L, and for atoms, molecules or formula units, use 6.02 x 10 23)
    3. Set up a “mole bridge” (the mole ratios from the balanced equation) to convert
       from moles of the “given” to moles of the “unknown.”
    4. Use the correct conversion factor to convert the moles of the “unknown” to the unit you
       need (for grams use molar mass, for volume use 22.4L, and for atoms, molecules or
       formula units, use 6.02 x 1023).

      The Mole Bridge – Still Your Best Tool (Next to the Periodic Table)




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                          1
                                         Guided Notes:
1. How would you explain “stoichiometry” in your own words?




2. How is stoichiometry related to balanced equations?




3. What is a “mole ratio?” (Include an example)




4. What does your book mean by a “mole-to-mole” problem? Include an example.




5. Using the sample problem on page 352 as your guide, solve this problem (show set-up and
   work): How many moles of HCl are required to react with 5.8 moles of Zinc?

    Balanced equation:


    Set-up and solve:




6. How does the concept of Stoichiometry support the conservation of matter?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                     2
                                         Guided Notes:
1. What are the major categories of Stoichiometry problems? (Hint: There are three!).
        a.
        b.
        c.



2. What is the general formula/set-up of ANY stoichiometry problem?




3. What is the general formula/set-up of a Mass-Mass stoichiometry problem?




4. What is the general formula/set-up of a Mass-Volume stoichiometry problem?




5. Explain the similarities between Mass-Mass, Mass-Volume, and Volume-Volume problems?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                         3
                                         Guided Notes:
1. How would you define a “limiting reactant?”




2. What happens when a limiting reactant is completely consumed and why?




3. How can you calculate which reactant is limiting?




4. How do you calculate your score on a quiz or test? Give an example.




5. What is “percent yield” and how do you calculate it? (Give an example)




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                             4
                         First the hamburger analogy! (Yum!)
My recipe for a bacon double cheeseburger is:
                         1 hamburger bun
                         2 hamburger patties
                         2 slices of cheese
                         4 strips of bacon


Based on this recipe:
    1. If I have five bacon double cheeseburgers:
            a. How many hamburger buns do I have?
            b. How many hamburger patties do I have?
            c. How many slices of cheese do I have?
            d. How many strips of bacon do I have?
    2. How many bacon double cheeseburgers can you make if you start with:
            a. 1 bun, 2 patties, 2 slices of cheese, 4 strips of bacon
            b. 2 bun, 4 patties, 4 slices of cheese, 8 strips of bacon
            c. 1 dozen bun, 2 dozen patties, 2 dozen slices of cheese, 4 dozen strips of bacon
            d. 1 mole bun, 2 mole patties, 2 mole slices of cheese, 4 mole strips of bacon
            e. 10 bun, 20 patties, 2 slices of cheese, 40 strips of bacon
    3. If you had fixings for 100 bacon double cheeseburgers, but when you were cooking you
       ruined 10 of them. What percentage of the bacon double cheeseburgers do you actually
       make?

Now, the chemistry problem.
NOTE: The math and the concepts are identical to the above example.
The only difference is the “recipe.”

Here are two examples of chemical recipes:
          +   -
    Na + Cl -> NaCl
    1 mole of H2SO4 + 2 mole NaOH produce 1 mole Na2SO4 + 2 mole H2O

Based on the recipes above:
   1. If I have 1 mole of NaCl
           a. How many moles of sodium do I have?
           b. How many moles of Chloride do I have?
   2. If I want to make 5 moles of Na2SO4:
           a. How many moles of H2SO4 do I need?
           b. How many moles of NaOH do I need?
   3. How much Na2SO4 can I make if I have:
           a. 1 mole of H2SO4 and 2 mole of NaOH
           b. 10 mole of H2SO4 and 20 mole of NaOH
           c. 0.1 mole of H2SO4 and 0.2 mole of NaOH
           d. 1 mole of H2SO4 and 20 mole of NaOH
           e. 0.42 mole of H2SO4 and 0.65 mole of NaOH
           f. 5 grams of H2SO4 and 5 grams of NaOH




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                         5
                               Skill Builder 1: Mole Ratios
The coefficient (number in front of the element or compound) in a balanced chemical equation
tells us what mole ratios we will have.
                                      Ex.     2Ca + O2 → 2CaO

We know from the above equation that
   2 moles of Ca will react with 1 mole of O2.
   2 moles of Ca will produce 2 moles of CaO.
   1 mole of O2 will produce 2 moles of CaO

So if I have .5 moles of Ca then how many moles of CaO will I produce?

        .5moles Ca      2 moles CaO = .5 moles CaO
                        2 moles Ca

If I have 3 moles of O2 then how many moles of CaO will I produce?

3 moles O2      2 moles CaO = 6 moles CaO
                1 moles O2


1. The combustion of acetylene gas is represented by this equation.
        2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(g)
        a. 2 moles of C2H2 will react with _____ moles of O2
        b. 5 moles of O2 will produce _____ moles of CO2
        c. 2 moles of C2H2 will produce _____ moles of H2O
        d. 2 moles of C2H2 will produce _____ moles of CO2
        e. If I have 7 moles of O2 how many moles of H2O will I produce?




        f. If I have 6.5 moles of C2H2 how many moles of CO2 will I produce?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                      6
2. Rusting of iron is represented by the equation 4Fe + 3O2 → 2Fe2O3.

    a. If I have 9 moles of Fe how many moles of Fe2O3 will I produce?




    b. If I produce 5 moles of Fe2O3 how many moles of O2 did I start with?




    c. If I have 13 moles of Fe how many moles of O2 will I react with?




3. Acetylene gas is produced by adding water to calcium carbide.
           CaC2(s) + 2H2O(l) → C2H2(g) + Ca(OH)2(aq)

        a. If I have 2.7 moles of CaC2 how many moles of Ca(OH)2 will I produce?




        b. If I produce 5.2 moles of Ca(OH)2 how many moles of CaC2 did I start with?




        c. If I have 6.3 moles of H2O how many moles of CaC2 will I react with?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                         7
    Skill Builder 2: Simple “Mole Ratio” Stoichiometry Worksheet
                                Show work on this page (Same as 11-1)

1. Lead will react with hydrochloric acid          6. How many moles of hydrogen will be
   to produce lead chloride and hydrogen.             produced if 0.44 mol of CaH2 reacts
   How many moles of hydrochloric acid are            according to the following equation?
   needed to completely react with 0.36 mol              CaH2 + 2H2O → Ca(OH)2 + 2H2
   of lead?



                                                   7. How many moles of oxygen will be needed
2. How many moles of HNO3 will be                     to react with 0.38 mol of C3H8 according to
   produced when 0.51 of N2O5 reacts                  the following equation?
   according to the following equation?                     C3H8 + 5O2 → 3CO2 + 4H2O?
           N2O5 + H2O → 2HNO3



                                                   8. Nitrogen can react with hydrogen to
3. Carbon will react with zinc oxide to               produce ammonia. How many moles
   produce zinc and carbon dioxide.                   of nitrogen will be needed to produce
   How many moles of carbon dioxide                   0.48 mol of NH3?
   will be produced if 0.38 mol of ZnO is
   completely reacted?


                                                   9. Iron will react with oxygen to produce
                                                      Fe2O3. How many moles of Fe2O3 will
                                                      be produced if 0.18 mol of Fe reacts?
4. How many moles of NaBr will be produced
   when 0.69 mol of bromine reacts according
   to the following equation?
           Br2 + 2NaI → 2NaBr + I2?
                                                   10. How many moles of water will be
                                                       produced if 2.35 mol of oxygen reacts
                                                       according to the following equation?
                                                          2C6H6 + 15O2 → 12CO2 + 6H2O?

5. Phosphorus will react with bromine to
   produce phosphorus tribromide. How many
   moles of phosphorus tribromide
   will be produced if 0.78 mol of bromine
   is reacted?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                          8
          Skill Builder 3: Getting More Comfortable with “Stoich”
Determine the mass of lithium hydroxide produced when 0.38g lithium nitride reacts with
water according to the following equation:
                                 Li3N + 3H2O  NH3 + 3LiOH
        Step 1: Make sure you have a balanced equation!
        Step 2: Identify the two “things” (elements or compounds) you are comparing, and circle
                them (in this example you are comparing lithium nitride and lithium hydroxide).
        Step 3: List your “given” and “unknown” amounts.
                G: 0.38 g Li3N
                U: mass (g) LiOH
        Step 4: Identify your Mole Ratio (1 mole Li3N : 3 mol LiOH). This ratio is your “Mole
                Bridge.”
        Step 5: Set up your T-chart including ALL units and formulas!

0.38 g Li3N          1 mole Li3N           3 mole LiOH            23.95 g LiOH         = 0.78 g LiOH
                     34.83 g Li3N           1 mole Li3N           1 mole LiOH

Now Try Some Practice Problems!
In the following problems, calculate how much of the indicated product is made. Show all your work.

1)      LiOH + HBr  LiBr + H2O
        If you start with ten grams of lithium hydroxide, how many grams of lithium bromide
        will be produced?



2)      C2H4 + 3 O2  2 CO2 + 2 H2O
        If you start with 45 grams of ethylene (C2H4), how many grams of carbon dioxide
        will be produced?



3)      Mg + 2 NaF  MgF2 + 2 Na
        If you start with 5.5 grams of lithium chloride, how many grams of calcium chloride
        will be produced?



4)      2 HCl + Na2SO4  2 NaCl + H2SO4
        If you start with 20 grams of hydrochloric acid, how many grams of sulfuric acid
        will be produced?



NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                                        9
                    Skill Builder 4: Stoichiometry Worksheet
                                        SHOW WORK to get credit

For the next 4 reactions, balance the equation for the reaction and give the mole to mole ratios.

1. PCl3 + H2O → H3PO3 +HCl




2. PbO → Pb + O2




3. Al + HCl → AlCl3 + H2




4. CaC2 + H2O → C2H2 + Ca(OH)2




5. How many moles of the product would be produced if you had 0.15 mol of Mg?
      2Mg + O2 → 2MgO




6. How many moles of the product would be produced if you had 0.15 mol of O2?
      2Mg + O2 → 2MgO




7. How many moles of the product would be produced if you had 0.15 mol of Fe?
       4Fe + 3O2 → 2Fe2O3




8. How many moles of the product would be produced if you had 0.15 mol of O2?
      4Fe + 3O2 → 2Fe2O3



NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                          10
9. How many grams of product would be produced if you had 0.50 mol of NH3?
      NH3 + HCl → NH4Cl




10. How many grams of each product would be produced if you had 0.50 mol of S?
       CH4 + 4S → CS2 + 2H2S




11. How many grams of each product would be produced if you had 0.50 mol of PCl 3?
       PCl3 + 3H2O →H3PO3 +3HCl




12. How many grams of each product would be produced if you had 12.5 g of H2?
       TiBr4 + H2 → Ti + HBr



13. How many grams of each product would be produced if you had 12.5 g of SiH4?
       SiH4 + NH3 → Si3N4 + H2




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                      11
                Skill Builder 5: More Stoichiometry Worksheet
                            Use a separate sheet of paper. (Same as 11-2)
1) Determine the mass of lithium hydroxide         7) Determine the mass of sodium nitrate
   produced when 0.38g of lithium nitride             produced when 0.73g of nickel (II) nitrate
   reacts with water according to the                 reacts with sodium hydroxide according
   equation:                                          to the following equation:
                                                       Ni(NO3) 2 + 2NaOH  Ni(OH) 2 + 2 NaNO3




2) What mass of sodium chloride is produced        8) Determine the mass of calcium hydroxide
   when chlorine reacts with 0.29 grams of            produced when calcium carbide reacts
   sodium iodide?                                     with 0.64 g of water according to the
                                                      following equation:
                                                      CaC2 + 2 H2O  Ca(OH) 2 + C2H2


3) Determine the mass of carbon dioxide
   produced when 0.85g of butane reacts with
   oxygen according to the following
   equation: 2C4H10 + 13O2  8CO2 + 10H2O    9) How many grams of ozone (O3) must
                                                decompose to produce 0.87 g of oxygen?



4) Determine the mass of antimony produced         10) Find the mass of sugar (C6H12O6) required
   when 0.46g of antimony (III) oxide reacts           to produce 1.82 L of carbon dioxide gas at
   with carbon according to the following              STP from the following equation:
   equation: Sb2O3+ 3C  2Sb + 3 CO                    C6H12O6  2 C6H6O + 2CO2




5) What mass of hydrogen peroxide (H2O2)           11) How many liters of oxygen are needed for
   must decompose to produce 0.77g of H2O?             the complete combustion of 425 g of sulfur,
                                                       assuming that the reaction occurs at STP?
                                                       S + O2  SO2



6) What mass of carbon dioxide must react
   with oxygen to produce 0.69g of carbon          12) Find the mass of benzene (C6H6) needed to
   dioxide?                                            produce 2.66 L of carbon dioxide gas at
                                                       STP from the following reaction:
                                                       2 C6H6 + 15O2  6H2O + 12CO2




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                         12
                Skill Builder 5: More Stoichiometry Worksheet
                            Use a separate sheet of paper. (Same as 11-2)
13) Find the mass of sodium needed to produce 20) What volumes of H2S gas and oxygen are
    5.68 L of hydrogen gas at STP from the        needed to produce 14.2 L of SO2 gas?
    following reaction:                           2H2S + 3 O2  2SO2 + 2 H2O
    2Na + 2H2O 2NaOH + H2



14) How many liters of oxygen gas are needed       21) What volumes of sulfur dioxide and
    for the complete combustion of 277 g of            dihydrogen sulfide gases are needed to
    carbon monoxide at STP?                            produce 11.4 L of water vapor?
    2CO + O2  2CO2                                    SO2 + 2H2S  3S + 2H2O



15) How many liters of oxygen gas are needed
    for the burning of 134 g of magnesium at       22) Glucose (C6H12O6) undergoes complete
    STP? (This is a synthesis reaction)                combustion. What volume of carbon
    2Mg + O2  2MgO                                    dioxide is produced when 3.7 L of oxygen
                                                       are consumed?
                                                       C6H12O6 + 6O2  6H2O + 6CO2


16) Find the mass (g) of aluminum needed
    to produce 4.72 L of oxygen gas at STP.        23) The compound TNT (trinitrotoluene)
    2Al + 3 H2SO4  Al2 (SO4) 3 + 3H2                  decomposes explosively into carbon,
                                                       carbon monoxide, hydrogen, and nitrogen.
                                                       What volumes of hydrogen and nitrogen
                                                       are produced if 5.8 L of CO is produced?
                                                       2C7H5(NO2) 3  2C + 12CO + 5H2 + 3N2
17) How many liters of hydrogen are produced
    if 225 g of iron reacts with hydrochloric
    acid (at STP)?                                 24) Nitroglycerin decomposes explosively into
    Fe + 2HCl  FeCl2 + H2                             carbon dioxide, water, nitrogen, and
                                                       oxygen. What volumes of oxygen and
                                                       nitrogen are produced if 4.3 L of CO2 is
                                                       produced?
18) Find the mass of S8 needed to produce              4C3H5(NO3) 3  12CO2 + 10H2O+ O2 + 6N2
    2.47 L of sulfur dioxide gas (at STP).
    S8 + 8O2  8SO2

                                                   25) Acetylene (C2H2) burns in oxygen to
                                                       produce carbon dioxide and water. What
19) Propane (C3H8) completely burns in                 volume of carbon dioxide is produced
    oxygen. What volume of carbon dioxide is           when 1.6 L of oxygen are consumed?
    produced when 2.8L of oxygen are used?             2C2H2 + 5O2  + 2H2O+ 4CO2
    C3H8 + 5O2  4H2O + 3 CO2



NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                         13
                    Skill Builder 6: Limiting Reactant Problems
Using your knowledge of stoichiometry and limiting reagents, answer the following questions:

1)      Write the balanced equation for the reaction of lead (II) nitrate with sodium iodide
        to form sodium nitrate and lead (II) iodide:




2)      If I start with 25.0 grams of lead (II) nitrate and 15.0 grams of sodium iodide, how many
        grams of sodium nitrate can be formed? Show all work with units.




3)      What is the limiting reactant in the reaction described in problem 2?




4)      How much of the excess (non-limiting) reactant will be left over from the reaction in
        problem #2?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                                14
        Skill Builder 7: Percent, Actual, and Theoretical Yield
1)      LiOH + KCl  LiCl + KOH

        a) I began this reaction with 20 grams of lithium hydroxide. What is my theoretical
        yield of lithium chloride?




        b) I actually produced 6 grams of lithium chloride. What is my percent yield?




2)      C3H8 + 5 O2  3 CO2 + 4 H2O

        a) If I start with 5 grams of C3H8, what is my theoretical yield of water?




        b) I got a percent yield of 75% How many grams of water did I make?




3)      Be + 2 HCl  BeCl2 + H2

        My theoretical yield of beryllium chloride was 10.7 grams. If my actual yield was 4.5
        grams, what was my percent yield?




4)      2 NaCl + CaO  CaCl2 + Na2O

        What is my theoretical yield of sodium oxide if I start with 20 grams of calcium oxide?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                         15
5)      FeBr2 + 2 KCl  FeCl2 + 2 KBr

        a) What is my theoretical yield of iron (II) chloride if I start with 34 grams of iron (II)
        bromide?




        b) What is my percent yield of iron (II) chloride if my actual yield is 4 grams?




6)      TiS + H2O  H2S + TiO

        What is my percent yield of titanium (II) oxide if I start with 20 grams of titanium (II)
        sulfide and my actual yield of titanium (II) oxide is 22 grams?




7)      U + 3 Br2  UBr6

        What is my actual yield of uranium hexabromide if I start with 100 grams of uranium and
        get a percent yield of 83% ?




8)      H2SO4  H2O + SO3

        If I start with 89 grams of sulfuric acid and produce 7.1 grams of water, what is my
        percent yield?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                             16
             Skill Builder 8: More Percent Yield Calculations
1)      Balance this equation and state which of the six types of reaction is taking place:

                          ____ Mg + ____ HNO3  ____ Mg(NO3)2 + ____ H2

                                                         Type of reaction: __________________________

2)      If I start this reaction with 40 grams of magnesium and an excess of nitric acid, how
        many grams of hydrogen gas will I produce?




3)      If 1.7 grams of hydrogen is actually produced, what was my percent yield of hydrogen?




4)      Balance the equation and (finals review!) state what type of reaction is taking place:

                                ____ NaHCO3  ____ NaOH + ____ CO2

                                                         Type of reaction: __________________________

5)      If 25 grams of carbon dioxide gas is produced in this reaction, how many grams of
        sodium hydroxide should be produced?




6)      If 50 grams of sodium hydroxide are actually produced, what was my percent yield?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                           17
         Skill Builder 9: Even More Percent Yield Calculations
1)      Write the equation for the reaction of iron (III) phosphate with sodium sulfate to make
        iron (III) sulfate and sodium phosphate.




2)      If I perform this reaction with 25 grams of iron (III) phosphate and an excess of sodium
        sulfate, how many grams of iron (III) sulfate can I make?




3)      If 18.5 grams of iron (III) sulfate are actually made when I do this reaction, what is my
        percent yield?




4)      Is the answer from problem #3 reasonable? Explain.




5) If I do this reaction with 15 grams of sodium sulfate and get a 65.0% yield, how many grams
   of sodium phosphate will I make?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                            18
           Skill Builder 10: Mixed Stoichiometry Review Problems
1. Hydrogen is produced when methane  CH4  reacts with water. Using 80.0 g of methane
     and 16.3 g of water, how many grams of H 2 can be produced at STP? What is the limiting
     reactant? CH 4  H 2O  CO 2  H 2




2.      Methyl alcohol  CH3OH  is made by reacting carbon monoxide with H 2 . Starting with
        2.5 g of H 2 and 30.0 g of CO , how much methyl alcohol could be produced at STP?
        Which is the limiting reactant?




3.      In a reaction of 15.3 g of NaCl with 60.8 g of Pb  NO3 2 , how many grams of lead (II)
        chloride will be produced? What is the limiting reactant?




4.      Diborane  B2H6  is widely used in the synthesis of organic compounds. Diborane itself
        is made by the reaction 2NaBH 4  I 2  B2 H 6  2NaI  H 2 . If 6.3 g of NaBH 4 are
        reacted with excess I 2 , how many grams of diborane could theoretically be isolated? If
        1.9 g of diborane is actually produced, what is the precent yield of the reaction?




5.      Ammonia gas can be produced by reacting CaO with NH 4Cl . Water and calcium
        chloride are produced in addition to ammonia. If 23.0 g of CaO and 50.0 g of NH 4Cl
        are mixed, what is the maximum possible volume of NH3 that can be produced at STP.
        If 16.1 L of NH3 are actually produced, what is the percent yield of NH3 ?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                          19
              Skill Builder 11: Another Mixed Review Sheet
                           Balancing Equations and Simple Stoichiometry

Balance the following equations:

1)      ___ N2 + ___ F2  ___ NF3

2)      ___ C6H10 + ___ O2  ___ CO2 + ___ H2O

3)      ___ HBr + ___ KHCO3  ___ H2O + ___ KBr + ___ CO2

4)      ___ GaBr3 + ___ Na2SO3  ___ Ga2(SO3)3 + ___ NaBr

5)      ___ SnO + ___ NF3  ___ SnF2 + ___ N2O3

Using the equation from problem 2 above, answer the following questions:

6)      If I do this reaction with 35 grams of C6H10 and 45 grams of oxygen, how many grams of
        carbon dioxide will be formed?




7)      What is the limiting reagent for problem 6? ___________

8)      How much of the excess reagent is left over after the reaction from problem 6 is finished?




9)      If 35 grams of carbon dioxide are actually formed from the reaction in problem 6, what is
        the percent yield of this reaction?




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                         20
                                   Chapter Test Study Guide
             You are expected to understand and be able to use everything in this packet
             whether or not we specifically review it in class on the day before an exam!
                      It is your responsibility to review all these core concepts.

1. Make sure you study all targets and vocabulary words. Any are fair game for the test.

2. Know how to determine which digits are significant when making measurements and
   when problem solving.

3. Understand the term “Stoichiometry” and know how and why we use it in Chemistry.

4. Understand how to pull the mole ratios out of a balanced chemical equations.

5. Solve stoichiometry problems involving mass, moles, volumes of gases, numbers of particles.
   (In other words – know your mole bridge!)

6. Define and be able to identify your limiting reactant in a chemical reaction.

7. Calculate the percent yield of a chemical reaction.

Practice for the Test!
For each of the following questions, write the balanced chemical equation, show all your work, and circle your final
answer, providing the appropriate sig figs, units, and substance:
Turn in on a separate sheet of paper – showing all work with units – for 10 homework points.
1)      ___ NaNO3 + ___ PbO  ___ Pb(NO3)2 + ___ Na2O
If 5.0 grams of NaNO3 is added to an excess amount of PbO, how many moles of Na2O can
be produced?


2)      ___ AgI + ___ Fe2(CO3)3  ___ FeI3 + ___ Ag2CO3
Assuming 5.2 moles of silver iodide is added to an excess amount of iron (III) carbonate, how
many formula units of iron (III) iodide can be produced?


3)      ___ C2H4O2 + ___ O2  ___ CO2 + ___ H2O
Assuming the following reaction occurs at STP, if 1.87 moles of oxygen gas is used in a
combustion reaction, how many liters of carbon dioxide can be produced?


4)      ___ ZnSO4 + ___ Li2CO3  ___ ZnCO3 + ___ Li2SO4
If 3.20 grams of zinc sulfate is added to an excess amount of lithium carbonate, how many grams
of lithium sulfate can be produced?

NCHS Chemistry: Unit 4, Chapters 10 and 11_2007                                                         21
5)      ___ V2O5 + ___ CaS  ___ CaO + ___ V2S5
When 4.5 x 1026 formula units of vanadium (V) oxide reacts with excess calcium sulfide,
how many moles of calcium oxide are produced?


6)      ___ S8 + ___ O2  ___ SO2
Assuming the above reaction occurs at STP, how many moles of sulfur dioxide are produced
if you begin with 2.33 liters of oxygen gas and plenty of sulfur?


7)      ______ Fe + ______ AgNO3  _____ Fe(NO3) 2 + _____Ag

If 40.0 grams of iron metal is allowed to react with excess silver nitrate, how many moles
of silver metal are produced?


8)    _______ NaOH(aq) + _______ H2SO4(aq)  ______ Na2SO4(aq) + _______ H2O(l)

Determine the limiting reactant, using the balanced equation given below, if 32.0 grams,
in solution, of sodium hydroxide reacts with a 41.3 grams equivalent of sulfuric acid.


For each of the following questions, balance the chemical equations, determine the
theoretical yield of the designated product, and determine the % yield.

9)      _______ Ag + _______Cl2  ________ AgCl

52.5 grams of silver react with 11.25 L of Cl2 at STP. How many grams of silver chloride will
be produced? If 35.2 g of AgCl are actually produced, what is the % yield?




10)     _______ Al + _______ Br2  ________ AlBr3

A mixture of 12.2 grams of aluminum and 22.2 grams of bromine was heated until the reaction
was complete. How many grams of potassium bromide could be formed? If 20.0 g of AlBr 3 are
actually produced, what is the % yield?




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                                           Misc. Notes:




NCHS Chemistry: Unit 4, Chapters 10 and 11_2007           23

				
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