Matching
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Match each item with the correct statement below. a. | actual yield | e. | limiting reagent | b. | percent yield | f. | mass | c. | theoretical
yield | g. | number of
molecules | d. | excess reagent | h. | volume |
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1.
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This quantity can always be used in the same way as moles when interpreting
balanced chemical equations.
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2.
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This is conserved only in reactions where the temperature is constant and the
number of moles of gaseous reactants is the same as that of gaseous products.
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3.
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the reactant that determines the amount of product that can be formed in a
reaction
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Multiple Choice
Identify the
choice that best completes the statement or answers the question.
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4.
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How many moles of H  PO 
are produced when 71.0 g P  O  reacts completely to form
H  PO  ?  a. | 0.063 5 mol | c. | 4.00 mol | b. | 1.00 mol | d. | 16.0 mol |
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5.
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How many grams of H  PO 
are produced when 10.0 moles of water react with an excess of P  O  ?  a. | 1.22 g | c. | 147 g | b. | 6.7 g | d. | 653 g |
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6.
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How many liters of hydrogen gas are needed to react with CS  to
produce 2.50 L of CH  at STP?  a. | 2.50 L | c. | 7.50 L | b. | 5.00 L | d. | 10.0 L |
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7.
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Which conversion factor do you use first to calculate the number of grams of
CO  produced by the reaction of 50.6 g of
CH  with O  ? The equation
for the complete combustion of methane is: 
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8.
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Which of the following statements is true about the following
reaction? 3NaHCO  ( aq) + C  H  O  ( aq) 
3CO  ( g) + 3H  O( s)
+Na  C  H  O  ( aq)
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9.
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How many liters of NH  are needed to react
completely with 30.0 L of NO (at STP)? 4NH  ( g) + 6NO( g)
 5N  ( g) +
6H  O( g) a. | 5.0 L | c. | 7.5 L | b. | 20.0 L | d. | 120.0 L |
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10.
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When 0.1 mol of calcium reacts with 880 g of water, 2.24 L of hydrogen gas form
(at STP). How would the amount of hydrogen produced change if the volume of water was decreased to
440 mL (440 g)?
a. | Only one half the volume of hydrogen would be produced. | b. | The volume of
hydrogen produced would be the same. | c. | The volume of hydrogen produced would
double. | d. | No hydrogen would be produced. |
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11.
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Glucose, C  H  O  ,
is a good source of food energy. When it reacts with oxygen, carbon dioxide and water are formed. How
many liters of CO  are produced when 126 g of glucose completely
react with oxygen? C  H  O  ( s) + 6O  ( g) 
6CO  ( g) + 6H  O( l) +
673 kcal a. | 4.21 L | c. | 15.7 L | b. | 5.33 L | d. | 94.1 L |
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12.
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Calcium oxide, or lime, is produced by the thermal decomposition of limestone in
the reaction CaCO  ( s)  CaO( s) +
CO  ( g). What mass of lime can be produced
from 1.5  10  kg of limestone? a. | 8.4  10 kg | c. | 8.4 kg | b. | 8.4  10 kg | d. | none of the
above |
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13.
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When two substances react to form products, the reactant which is used up is
called the ____.
a. | determining reagent | c. | excess reagent | b. | limiting reagent | d. | catalytic
reagent |
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14.
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Which of the following is NOT true about limiting and excess reagents?
a. | The amount of product obtained is determined by the limiting
reagent. | b. | A balanced equation is necessary to determine which reactant is the limiting
reagent. | c. | Some of the excess reagent is left over after the reaction is
complete. | d. | The reactant that has the smallest given mass is the limiting
reagent. |
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15.
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How many grams of chromium are needed to react with an excess of CuSO  to produce 27.0 g Cu? 2Cr( s) + 3CuSO  ( aq)
 Cr  (SO  )  ( aq) + 3Cu( s) a. | 14.7 g | c. | 33.2 g | b. | 18.0 g | d. | 81.5 g |
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16.
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How many grams of beryllium are needed to produce 36.0 g of hydrogen? (Assume an
excess of water.) Be( s) + 2H  O( l)  Be(OH)  ( aq) +
H  ( g) a. | 4.00 g | c. | 162 g | b. | 36.0 g | d. | 324 g |
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17.
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How many liters of NH  , at STP, will react with 5.3
g O  to form NO  and
water? 4NH  ( g) + 7O  ( g)
 4NO  + 6H  O( g) a. | 0.004 23 L | c. | 3.03 L | b. | 2.12 L | d. | 6.49 L |
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18.
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How many liters of chlorine gas can be produced when 0.98 L of HCl react with
excess O  at STP? 4HCl( g) + O  ( g)  2Cl  ( g) + 2H  O( g) a. | 0.98 L | c. | 3.9 L | b. | 0.49 L | d. | 2.0 L |
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19.
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Identify the limiting reagent and the volume of CO  formed when 11 L
CS  reacts with 18 L O  to
produce CO  gas and SO  gas at
STP. CS  ( g) + 3O  ( g)
 CO  ( g) +
2SO  ( g)
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20.
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What is the maximum number of grams of PH  that can be
formed when 6.2 g of phosphorus reacts with 4.0 g of hydrogen to form PH  ? P  ( g) + 6H  ( g)
 4PH  ( g) a. | 0.43 g | c. | 270 g | b. | 6.8 g | d. | 45 g |
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21.
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Methane and hydrogen sulfide form when hydrogen reacts with carbon disulfide.
Identify the excess reagent and calculate how much remains after 36 L of H 
reacts with 12 L of CS  . 4H  ( g) +
CS  ( g) 
CH  ( g) + 2H  S( g) a. | 3 L CS | c. | 9 L CS | b. | 6 L CS | d. | 12 L
H |
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22.
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Metallic copper is formed when aluminum reacts with copper(II) sulfate. How many
grams of metallic copper can be obtained when 54.0 g of Al react with 319 g of CuSO  ? Al + 3CuSO   Al  (SO  )  + 3Cu a. | 21.2 g | c. | 162 g | b. | 127 g | d. | 381 g |
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23.
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Which statement is true if 12 mol CO and 12 mol Fe  O  are allowed to react? 3CO( g) +
Fe  O  ( s)  2Fe( s) + 3CO  ( g) a. | The limiting reagent is CO and 8.0 mol Fe will be formed. | b. | The limiting reagent
is CO and 3.0 mol CO will be formed. | c. | The limiting reagent
is Fe O and 24 mol Fe will be
formed. | d. | The limiting reagent is Fe O and 36 mol CO will be formed. |
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24.
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Which of the following would be the limiting reagent in the reaction shown
below? 2H  ( g) + O  ( g)
 2H  O( g) a. | 50 molecules of H | b. | 50 molecules of O | c. | Neither a nor b is
limiting. | d. | Both a and b are considered limiting reagents. |
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25.
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When an equation is used to calculate the amount of product that will form
during a reaction, then the value obtained is called the ____.
a. | actual yield | c. | theoretical yield | b. | percent yield | d. | minimum yield |
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26.
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Which of the following is NOT true about "yield"?
a. | The value of the actual yield must be given in order for the percent yield to be
calculated. | b. | The percent yield is the ratio of the actual yield to the theoretical
yield. | c. | The actual yield may be different from the theoretical yield because reactions do not
always go to completion. | d. | The actual yield may be different from the
theoretical yield because insufficient limiting reagent was used. |
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27.
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Which of the following is NOT a reason why actual yield is less than theoretical
yield?
a. | impure reactants present | c. | loss of product during
purification | b. | competing side reactions | d. | conservation of mass |
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28.
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Lead nitrate can be decomposed by heating. What is the percent yield of the
decomposition reaction if 9.9 g Pb(NO  )  are heated to give 5.5 g of
PbO? 2Pb(NO  )  ( s)  2PbO( s) + 4NO  ( g) + O  ( g)
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29.
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Hydrogen gas is produced when zinc reacts with hydrochloric acid. If the actual
yield of this reaction is 85%, how many grams of zinc are needed to produce 112 L of H  at STP? Zn( s) + 2HCl( aq) 
ZnCl  ( s) + H  ( g) a. | 95 g | c. | 280 g | b. | 180 g | d. | 380 g |
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30.
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In a particular reaction between copper metal and silver nitrate, 12.7 g Cu
produced 38.1 g Ag. What is the percent yield of silver in this reaction? Cu + 2AgNO   Cu(NO  )  + 2Ag a. | 56.7% | c. | 88.2% | b. | 77.3% | d. | 176% |
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