Download Stoich chem reactions practice Answer Section

Stoich chem reactions practice
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. Which observation does NOT indicate that a chemical reaction has occurred?
a. formation of a precipitate
c. evolution of heat and light
b. production of a gas
d. change in total mass of substances
2. In writing an equation that produces hydrogen gas, the correct representation of hydrogen gas is
a. H.
c. H2.
b. 2H.
d. OH.
3. To balance a chemical equation, it may be necessary to adjust the
a. coefficients.
c. formulas of the products.
b. subscripts.
d. number of products.
4. Which word equation represents the reaction that produces water from hydrogen and oxygen?
a. Water is produced from hydrogen and oxygen.
b. Hydrogen plus oxygen yields water.
c. H2 + O2  water.
d. Water can be separated into hydrogen and oxygen.
5. When the equation Fe3O4 + Al  Al2O3 + Fe is correctly balanced, what is the coefficient of Fe?
a. 3
c. 6
b. 4
d. 9
6. In what kind of reaction do two or more substances combine to form a new compound?
a. decomposition reaction
c. double-replacement reaction
b. ionic reaction
d. synthesis reaction
7. The equation AX  A + X is the general equation for a
a. synthesis reaction.
c. combustion reaction.
b. decomposition reaction.
d. single-replacement reaction.
8. The equation AX + BY  AY + BX is the general equation for a
a. synthesis reaction.
c. single-replacement reaction.
b. decomposition reaction.
d. double-replacement reaction.
9. In what kind of reaction does a single compound produce two or more simpler substances?
a. decomposition reaction
c. single-replacement reaction
b. synthesis reaction
d. ionic reaction
10. The reaction Mg(s) + 2HCl(aq)  H2(g) + MgCl2(aq) is a
a. composition reaction.
c. single-replacement reaction.
b. decomposition reaction.
d. double-replacement reaction.
11. The reaction 2KClO3(s)  2KCl(s) + 3O2(g) is a(n)
a. synthesis reaction.
c. combustion reaction.
b. decomposition reaction.
d. ionic reaction.
12. Which branch of chemistry deals with the mass relationships of elements in compounds and the mass
relationships among reactants and products in chemical reactions?
a. qualitative analysis
c. chemical kinetics
b. entropy
d. stoichiometry
13. The coefficients in a chemical equation represent the
a. masses, in grams, of all reactants and products.
b. relative numbers of moles of reactants and products.
____ 14.
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c. number of atoms in each compound in a reaction.
d. number of valence electrons involved in the reaction.
Each of the four types of reaction stoichiometry problems requires using a
a. table of bond energies.
c. Lewis structure.
b. chart of electron configurations.
d. mole ratio.
In the reaction N2 + 3H2  2NH3, what is the mole ratio of nitrogen to ammonia?
a. 1:1
c. 1:3
b. 1:2
d. 2:3
In the reaction 2H2 + O2  2H2O, what is the mole ratio of oxygen to water?
a. 1:2
c. 8:1
b. 2:1
d. 1:4
In the reaction C + 2H2  CH4, what is the mole ratio of hydrogen to methane?
a. 1:1
c. 1:2
b. 2:1
d. 2:4
The Haber process for producing ammonia commercially is represented by the equation N2(g) + 3H2(g) 
2NH3(g). To completely convert 9.0 mol hydrogen gas to ammonia gas, how many moles of nitrogen gas are
required?
a. 1.0 mol
c. 3.0 mol
b. 2.0 mol
d. 6.0 mol
For the reaction C + 2H2  CH4, how many moles of hydrogen are required to produce 10 mol of methane,
CH4?
a. 2 mol
c. 10 mol
b. 4 mol
d. 20 mol
For the reaction AgNO3 + NaCl  NaNO3 + AgCl, how many moles of silver chloride, AgCl, are produced
from 7 mol of silver nitrate AgNO3?
a. 1.0 mol
c. 7.0 mol
b. 2.3 mol
d. 21 mol
Element
Bromine
Calcium
Carbon
Chlorine
Cobalt
Symbol
Br
Ca
C
Cl
Co
Copper
Fluorine
Cu
F
Hydrogen
H
Iodine
Iron
Lead
Magnesium
Mercury
Nitrogen
I
Fe
Pb
Mg
Hg
N
Oxygen
O
Atomic mass
79.904
40.078
12.011
35.4527
58.933
20
63.546
18.998
4032
1.007
94
126.904
55.847
207.2
24.3050
200.59
14.006
74
15.9994
Potassium
Sodium
K
Na
Sulfur
S
39.0983
22.989
768
32.066
____ 21. For the reaction 2Na + 2H2O  2NaOH + H2, how many grams of sodium hydroxide are produced from 3.0
mol of water?
a. 40. g
c. 120 g
b. 80. g
d. 240 g
____ 22. For the reaction 2Na + Cl2  2NaCl, how many grams of chlorine gas are required to react completely with
2.00 mol of sodium?
a. 35.5 g
c. 141.8 g
b. 70.9 g
d. 212.7 g
____ 23. For the reaction CH4 + 2O2  CO2 + 2H2O, how many moles of carbon dioxide are produced from the
combustion of 100. g of methane?
a. 6.23 mol
c. 12.5 mol
b. 10.8 mol
d. 25 mol
____ 24. For the reaction 2KlO3  2KCl + 3O2, how many moles of potassium chlorate are required to produce 250 g
of oxygen?
a. 2.0 mol
c. 4.9 mol
b. 4.3 mol
d. 5.2 mol
____ 25. For the reaction 2Na + Cl2  2NaCl, how many grams of sodium chloride can be produced from 500. g each
of sodium and chlorine?
a. 112 g
c. 409 g
b. 319 g
d. 825 g
____ 26. For the reaction SO3 + H2O  H2SO4, how many grams of sulfuric acid can be produced from 200. g of
sulfur trioxide and 100. g of water?
a. 100. g
c. 245 g
b. 200. g
d. 285 g
____ 27. For the reaction Cl2 + 2KBr  2KCl + Br2, calculate the percent yield if 200. g of chlorine react with excess
potassium bromide to produce 410. g of bromine.
a. 73.4%
c. 91.0%
b. 82.1%
d. 98.9%
____ 28. For the reaction 2Na + 2H2O  2NaOH + H2, calculate the percent yield if 80. g of water react with excess
sodium to produce 4.14 g of hydrogen.
a. 87%
c. 92%
b. 89%
d. 98%
____ 29. What is the measured amount of a product obtained from a chemical reaction?
a. mole ratio
c. theoretical yield
b. percent yield
d. actual yield
____ 30. A chemist interested in the efficiency of a chemical reaction would calculate the
a. mole ratio.
c. percent yield.
b. energy released.
d. rate of reaction.
Short Answer
31. When a glass blower shapes molten glass into an ornament, does a chemical reaction occur? Explain.
Problem
Element
Bromine
Calcium
Carbon
Chlorine
Cobalt
Symbol
Br
Ca
C
Cl
Co
Copper
Fluorine
Cu
F
Hydrogen
H
Iodine
Iron
Lead
Magnesium
Mercury
Nitrogen
I
Fe
Pb
Mg
Hg
N
Oxygen
Potassium
Sodium
O
K
Na
Sulfur
S
Atomic mass
79.904
40.078
12.011
35.4527
58.933
20
63.546
18.998
4032
1.007
94
126.904
55.847
207.2
24.3050
200.59
14.006
74
15.9994
39.0983
22.989
768
32.066
32. What mass in grams of sodium hydroxide is produced if 20.0 g of sodium metal reacts with excess water
according to the chemical equation 2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)?
33. What mass in grams of 1-chloropropane (C3H7Cl) is produced if 400. g of propane react with excess chlorine
gas according to the equation C3H8 + Cl2  C3H7Cl + HCl?
34. What mass in grams of hydrogen gas is produced if 20.0 mol of Zn are added to excess hydrochloric acid
according to the equation Zn(s) +2HCl(aq)  ZnCl2(aq) + H2( )?
35. How many grams of ammonium sulfate can be produced if 30.0 mol of H2SO4 react with excess NH3
according to the equation 2NH3(aq) + H2SO4(aq)  (NH4)2SO4(aq)?
36. How many moles of Ag can be produced if 350. g of Cu are reacted with excess AgNO3 according to the
equation Cu(s) + 2AgNO3(aq)  2Ag(s) + Cu(NO3)2(aq)?
Stoich chem reactions practice
Answer Section
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SHORT ANSWER
31. ANS:
A chemical reaction does not occur. Analysis of the molten glass and the glass in the ornament would reveal
that both substances have the same chemical properties.
PTS: 1
PROBLEM
32. ANS:
34.8 g NaOH
PTS: 1
33. ANS:
712 g C3H7Cl
PTS: 1
34. ANS:
40.4 g H2
PTS: 1
35. ANS:
3960 g (NH4)2SO4
PTS: 1
36. ANS:
11.0 mol Ag
PTS: 1