Name__________________
Practice Test
Moles & Stoich
1. What is the total number of nitrogen atoms in 0.25 mole of
NO2 gas?
(1) 1.5 × 1023
(2) 6.0 × 1023
10. The percent composition by mass of nitrogen in NH 4OH
(gram-formula mass = 35 grams/mole) is equal to
(3) 3.0 × 1023
(4) 1.2 × 1024
(1)
2. Which quantity of O2 contains exactly 3.01 × 1023 molecules?
(1) 0.250 mole
(2) 0.500 mole
(3) 16.0 moles
(4) 32.0 moles
3. Given the balanced equation representing a reaction:
×
100
(2)
×
100
(3)
×
100
(4)
×
100
11. A hydrated salt is a solid that includes water molecules
within its crystal structure. A student heated a 9.10-gram
sample of a hydrated salt to a constant mass of 5.41 grams.
What percent by mass of water did the salt contain?
(1) 3.69%
(2) 16.8%
(3) 40.5%
(4) 59.5%
12. A compound has an empirical formula of HCO2 and a
molecular mass of 90. grams per mole. What is the
molecular formula of this compound?
The mole ratio of
(1) 1:1
(2) 1:3
to
(3) 3:1
(1) HCO
(2) H2C2O4
is
(4) 3:7
13. The empirical formula of a compound is CH2O and the
molecular mass is 180. What is the molecular formula of this
compound?
4. Which chemical equation is correctly balanced?
(1)
(2)
(3)
(4)
H2(g) + O2(g) ® H2O(g)
N2(g) + H2(g) ® NH3(g)
2NaCl(s) ® Na(s) + Cl2(g)
2KCl(s) ® 2K(s) + Cl2(g)
(1) C6H12O6
(2) C4H8O4
(1) 1.0 g
(3) formed
(4) released
(1) 16 g
(1) 1
(2) 24 g
(2) 15
(1) 112 g/mol
(2) 121 g/mol
8. In which type of chemical reaction do two or more reactants
combine to form one product, only?
(3) single replacement
(4) double replacement
9. Which balanced equation represents a chemical change?
(1)
(2)
(3)
(4)
(4) 4.0 g
(3) 32 g
(4) 48 g
(3) 3
(4) 17
17. What is the gram-formula mass of (NH4)3PO4?
decomposition and sublimation
decomposition and synthesis
deposition and sublimation
deposition and synthesis
(1) synthesis
(2) decomposition
(3) 3.0 g
16. What is the total number of moles of sulfur atoms in 1 mole
of Fe2(SO4)3?
(3) H2 + O2 ® H2O
(4) H2 + O2 ® 2 H2O
7. Which terms identify types of chemical reactions?
(1)
(2)
(3)
(4)
(2) 2.0 g
15. What is the total mass in grams of 0.75 mole of SO2?
6. Which equation illustrates conservation of mass?
(1) H2 + Cl2 ® HCl
(2) H2 + Cl2 ® 2 HCl
(3) C2H4O2
(4) CH2O
14. What is the total mass of 2.0 moles of H 2(g)?
5. During all chemical reactions, mass is
(1) absorbed
(2) conserved
(3) H4C4O8
(4) H6C6O12
H2O( ) + energy ® H2O(g)
2H2O( ) + energy ® 2H2(g) + O2(g)
H2O( ) ® H2O(s) + energy
H2O(g) ® H2O( ) + energy
Page 1
(3) 149 g/mol
(4) 242 g/mol
Name__________________
Practice Test
Moles & Stoich
18. Given the formula for a compound:
Which molecular formula and empirical formula represent
this compound?
(1)
(2)
(3)
(4)
C2HNO2 and CHNO
C2HNO2 and C2HNO2
C4H2N2O4 and CHNO
C4H2N2O4 and C2HNO2
19. Which type of formula represents the simplest
whole-number ratio of atoms of the elements in a
compound?
(1) molecular formula
(2) condensed formula
(3) empirical formula
(4) structural formula
20. What is the total number of atoms contained in 2.00 moles of
nickel?
(3) 6.02 × 1023
(4) 1.20 × 1024
(1) 58.9
(2) 118
21. One mole of which substance contains a total of
atoms?
(1) Li
(2) NH3
(3) O2
(4) CO2
22. A compound has the empirical formula NO2. Its molecular
formula could be
(1) NO2
(2) N2O
(3) N4O2
(4) N4O4
23. Base your answer to the following question on
the information below and on your knowledge of chemistry.
A student made a copper bracelet by hammering a small copper bar into the desired shape. The bracelet has a
mass of 30.1 grams and was at a temperature of 21°C in the classroom. After the student wore the bracelet, the
bracelet reached a temperature of 33°C. Later, the student removed the bracelet and placed it on a desk at home,
where it cooled from 33°C to 19°C. The specific heat capacity of copper is 0.385 J/g• K.
Determine the number of moles of copper in the bracelet.
Page 2
Name__________________
Practice Test
Moles & Stoich
24. Base your answer to the following question on the information below and on your knowledge of chemistry.
The nuts, bolts, and hinges that attach some gates to a playground fence can be made of iron. The iron can
react with oxygen in the air. The unbalanced equation representing this reaction is shown below.
Balance the equationfor the reaction, using the smallest whole-number coefficients.
25. Base your answer to the following question on
the information below and on your knowledge of chemistry.
Many breads are made by adding yeast to dough, causing the dough to rise. Yeast is a type of microorganism
that produces the catalyst zymase, which converts glucose,
, to ethanol and carbon dioxide gas. The
balanced equation for this reaction is shown below.
Determine the total mass of ethanol produced when 270. grams of glucose reacts completely to form ethanol and 132
grams of carbon dioxide.
26. Base your answer to the following question on
the information below.
The reaction between aluminum and an aqueous solution of copper(II) sulfate is represented by the
unbalanced equation below.
Al (s) + CuSO4(aq)
Al2(SO4)3(aq) + Cu(s)
Determine the total mass of Cu produced when 1.08 grams of Al reacts completely with 9.58 grams of CuSO4 to
produce 6.85 grams of Al2(SO4)3.
27. Base your answer to the following question on
the information below.
The Solvay process is a multistep industrial process used to produce washing soda, Na2CO3(s). In the last step of the
Solvay process, NaHCO3(s) is heated to 300°C, producing washing soda, water, and carbon dioxide. This reaction is
represented by the balanced equation below.
2NaHCO3(s) + heat
Na2CO3(s) + H2O(g) + CO2(g)
Identify the type of chemical reaction represented by the equation.
Page 3
Name__________________
Practice Test
Moles & Stoich
28. Given the balanced equation representing a reaction:
Determine the total number of moles of oxygen that react completely with
moles of
.
29. Base your answer to the following question on the following paragraph.
A portable propane-fueled lantern contains a mesh silk bag coated with metal hydroxides. The primary metal
hydroxide is yttrium hydroxide. When the silk bag is installed, it is ignited and burned away, leaving the metal
hydroxide coating. The coating forms metal oxides that glow brightly when heated to a high temperature.
During a test, a propane lantern is operated for three hours and consumes 5.0 moles of propane from the
lantern’s tank. The balanced equation below represents the combustion of propane.
C3H8 + 5O2 3CO2 + 4H2O + energy
Determine the total number of moles of CO2 produced during the lantern test.
30. Base your answer to the following question on the following information.
A piece of magnesium ribbon is reacted with excess hydrochloric acid to produce aqueous magnesium chloride
and hydrogen gas. The volume of the dry hydrogen gas produced is 45.6 milliliters. The temperature of the gas
is 293 K, and the pressure is 99.5 kilopascals.
Balance below using the smallest whole-number coefficients.
____Mg(s) + ____HCl(aq) ® ____MgCl2(aq) + ____H2(g)
31. Write the empirical formula for the compound
C8H18.
33. Identify the type of chemical reaction represented by this
equation.
Base your answers to questions 32 and 33 on
the information below.
Rust on an automobile door contains Fe2O3(s). The balanced
equation representing one of the reactions between iron in
the door of the automobile and oxygen in the atmosphere is
given below.
4Fe(s) + 3O2(g)
2Fe2O3(s)
32. Determine the gram-formula mass of the product of this
reaction.
Page 4
Name__________________
Practice Test
Moles & Stoich
34. Determine the percent composition by mass of oxygen in the compound C6H12O6
35. What is the mass of 4.76 moles of Na3PO4 (gram-formula
mass = 164 grams/mole)?
36. Show a correct numerical setup for calculating the number
of moles of CO2 (gram-formula mass = 44 g/mol) present in
11 grams of CO2.
Base your answers to questions 37 through 39 on the information below and on your knowledge of chemistry.
In 1828, Friedrich Wöhler produced urea when he heated a solution of ammonium cyanate. This reaction is
represented by the balanced equation below.
37. Explain why this balanced equation represents a conservation of atoms.
38. Write an empirical formula for the product.
39. Determine the gram-formula mass of the product.
40. Given the unbalanced equation:
__NH3 + __O2 ® __HNO3 + __ H2O
balance the equation using the smallest whole number
coefficients.
Page 5
Answer Key
Moles & Stoich PRACTICE Exam
1.
1
30.
___Mg(s) + _2
_HCl(aq) ®
___MgCl 2(aq) +
____H2(g)
2.
2
3.
3
4.
4
5.
2
31.
C4H 9
6.
2
32.
160.g/mol.
7.
2
33.
8.
1
9.
2
Examples: –
synthesis – redox –
oxidation
10.
2
34.
53.3%
11.
3
35.
781 g
12.
2
36.
11 g ×
13.
1
37.
14.
4
15.
4
16.
3
17.
3
18.
4
19.
3
— There are the
same number of
atoms of each
element on both
sides of the
equation. — No
atoms are lost or
gained.
20.
4
38.
21.
1
39.
22.
1
60. g/mol
40.
1 NH 3 + 2 O2 ®
1 HNO3 + 1 H2O
23.
0.474 mol or for any
value from 0.47 mol
to 0.47402 mol,
inclusive, or for 0.5
mol
or
24.
25.
138 g or for any
value from 137.8 g
to 138.3 g, inclusive
26.
3.81 g
27.
decomposition
28.
Examples:
29.
15 mol
mol
Page 6