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 P4B. / 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 molB. / 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 molB. / 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 O2B. / 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 gB. / 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 gB. / 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 molB. / 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 gB. / 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.ANS:E
2.ANS:A
3.ANS:C
4.ANS: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.ANS:A
24.ANS:B
25.ANS:
3.93 x 1023 Al atoms