Download Unit 8 Stoichiometry Review

Unit 8 Stoichiometry Review
1. The balanced equation
P4(s) + 6H2(g) --> 4PH3(g)
tells us that 2 mol H2
A. reacts with 1 mol P4
B. produces 4 mol PH3
C. cannot react with phosphorus
D. reacts with 2 mol P4
E. produces 2 mol PH3
2. The rusting of iron is represented by the equation
4Fe + 3O2 --> 2Fe2O3.
If you have a 1.50-mol sample of iron, how many
moles of Fe2O3 will there be after the iron has
rusted completely?
A. 0.75 mol
B. 1.50 mol
C. 0.50 mol
D. 1.0 mol
E. 2.0 mol
3. A 3.0-mol sample of KClO3 was decomposed,
according to the equation
2KClO3(s) --> 2KCl(s) + 3O2(g).
How many moles of O2 are formed assuming 100%
yield?
A. 3.0 mol
B. 2.0 mol
C. 4.5 mol
D. 2.5 mol
E. 4.0 mol
4. What mass of oxygen would be required to
completely burn 6.75 g of propane in the following
reaction?
C3H8(g) + 5O2(g) --> 3CO2(g) + 4H2O(g)
A. 49.0 g O2
B. 122 g O2
C. 24.5 g O2
D. 77.4 g O2
E. 33.8 g O2
5. How many moles of oxygen are produced by
decomposing 41.1 g of H2O2 (molar mass = 34.0
g/mol), according to the equation
2H2O2(l) --> 2H2O(l) + O2(g)?
6. In the reaction
Cu(s) + 2AgNO3(aq) --> 2Ag(s) + Cu(NO3)2(aq),
what number of grams of silver can be produced
from 49.1 g of copper?
7. Methane, CH4, the major component of natural gas,
burns in air to form CO2 and H2O. What mass of
water is formed in the complete combustion of 5.00
x 103 g of CH4?
A. 1.00 x 104 g
B. 5.00 x 103 g
C. 5.65 x 103 g
D. 1.12 x 104 g
E. None of the above
8. If 18.0 g of CO2 is produced in the reaction of C2H2
with O2 to form CO2 and H2O, how many grams of
H2O are produced in this reaction?
A. 3.68 g
B. 7.37 g
C. 9.0 g
D. 14.7 g
E. None of the above
9. What number of moles of ammonia can be
produced from 8.0 g of hydrogen gas and excess
nitrogen gas?
10. In the reaction
3Cl2(g) + 6NaOH(aq) --> 5NaCl(aq) +
NaClO3(aq) + 3H2O(l),
how many moles of chlorine molecules are needed
to react with 10.9 g of NaOH?
11. In the reaction
3Cl2(g) + 6NaOH(aq) --> 5NaCl(aq) +
NaClO3(aq) + 3H2O(l),
how many grams of sodium chloride can be
produced from 10.9 g of NaOH?
12. For the reaction
2S(s) + 3O2(g) --> 2SO3(g),
how many moles of SO3 will be produced from 2.0
mol O2 and excess S?
13. For the reaction
2S(s) + 3O2(g) --> 2SO3(g),
how many moles of SO3 can be produced from 8.0
g O2 and excess S?
14. For the reaction
CaCO3(s) + 2HCl(aq) --> CaCl2(aq) + CO2(g) +
H2O(l),
how many grams of CaCl2 could be obtained if 15.0
g HCl is allowed to react with excess CaCO3?
15. For the reaction
2Cl2(g) + 4NaOH(aq) --> 3NaCl(aq) +
NaClO2(aq) + 2H2O(l),
how many moles of Cl2 are needed to react with
14.4 g NaOH?
16. For the reaction
2Cl2(g) + 4NaOH(aq) --> 3NaCl(aq) +
NaClO2(aq) + 2H2O(l),
how many grams of NaCl can be produced from
10.9 g of Cl2 and excess NaOH?
17. Fe2O3 (molar mass = 159.7 g/mol) reacts with CO
(molar mass = 28.0 g/mol), according to the
equation
Fe2O3(s) + 3CO(g) --> 3CO2(g) + 2Fe(s).
When 352 g Fe2O3 reacts with excess CO, what
number of moles of Fe (iron) is produced?
18. For the reaction
2S(s) + 3O2(g) --> 2SO3(g),
if 6.3 g of S is reacted with 10.0 g of O2, show by
calculation which one will be the limiting reactant.
19. Consider the reaction
Mg2Si(s) + 4H2O(l) --> 2Mg(OH)2(aq) + SiH4(g).
Which of the reactants is in excess if we start with
50.0 g of each reactant?
20. In the reaction between CO and Fe3O4, the
theoretical yield in an experiment is calculated to
be 47.2 g Fe. When a careless chemistry student
carries out the experiment, the actual yield is 42.9 g
Fe. Calculate the percentage yield.
21. Consider the following unbalanced equation: Al4C3
+ H2O --> Al(OH)3 + CH4. How many moles of
Al(OH)3 will be produced when 0.600 mol of CH4
is formed?
A. 0.600 mol
B. 0.800 mol
C. 0.450 mol
D. 0.164 mol
E. None of the above
22. In the reaction of C8H18(l) with O2(g), to form
CO2(g) and H2O(g), 2.28 g C8H18 is reacted with
7.00 g of O2. Determine which is the limiting
reactant.
23. Consider the equation:
A + 3B --> 4C.
If you react 3.0 moles of A with 6.0 moles of B,
which of the following is true after the reaction is
complete?
A. A is the leftover reactant because you only need
2 moles of A and have 3.
B. A is the leftover reactant because for every 1
mole of A, 4 moles of C are produced.
C. B is the leftover reactant because you have
more moles of B than A.
D. B is the leftover reactant because 3 moles of B
react with every 1 mole of A.
E. Neither reactant is leftover.
24. Consider the following reaction: 3Fe(s) + 4H2O(g) -> Fe3O4(s) + 4H2(g). How many grams of steam
must react to produce 375 g of Fe3O4?
A. 6.48 g
B. 117 g
C. 29.2 g
D. 44.5 g
E. 161 g
25. How many atoms of aluminum can be produced by
the decomposition of 33.3 g of Al2O3? Hint: Write
and balance the equation first.
Unit 8 Stoichiometry Review
Answer Section
1.
2.
3.
4.
ANS:
ANS:
ANS:
ANS:
E
A
C
C
5. ANS:
0.604 mol O2
6. ANS:
167 g Ag
7.
ANS: D
8.
ANS: A
9. ANS:
2.65 mol NH3
10. ANS:
0.136 mol Cl2
11. ANS:
13.3 g NaCl
12. ANS:
1.3 mol SO3
13. ANS:
0.17 mol SO3
14. ANS:
22.8 g CaCl2
15. ANS:
0.180 mol Cl2
16. ANS:
13.5 g NaCl
17. ANS:
4.41 mol Fe
18. ANS:
S is the limiting reactant
19. ANS:
H2O is in excess
20. ANS:
90.9%
21.
ANS: B
22. ANS:
O2 is the limiting reactant
23.
24.
25. ANS:
3.93 x 1023 Al atoms
ANS: A
ANS: B