Chapter 10 PRACTICE
MOORE
1. What is the empirical formula of a compound with the
molecular formula N 2O4?
A) NO
B) NO 2
C) N2O
D) N2O3
2. Which substance has a chemical formula with the same
ratio of metal ions to nonmetal ions as in potassium
sulfide?
A) sodium oxide
C) magnesium oxide
B) sodium chloride
D) magnesium chloride
3. Which pair consists of a molecular formula and its
corresponding empirical formula?
A)
B)
C)
D)
C2 H2 and CH 3 CH 3
C6 H6 and C2H2
P4O10 and P 2O5
SO 2 and SO3
A) The proportion by mass of elements combined in
potassium chlorate is fixed.
B) The proportion by mass of elements combined in
potassium chlorate varies.
C) Potassium chlorate is composed of four elements.
D) Potassium chlorate is composed of five elements.
5. Which pair of formulas correctly represents a molecular
formula and its corresponding empirical formula?
B) C3H4 and CH 2
D) C5H8 and C2H2
B) P4O6
7. What is the total mass of iron in 1.0 mole of Fe 2O3?
D) 56 g
B) S
C) LiH
D) Cl 2
9. What is the total number of moles in 80.0 grams of C 2H5
Cl (gram-formula mass = 64.5 grams/mole)?
10. The number of moles of molecules in a
sample of
is
A)
C)
mole
moles
A) 1:1:2 B) 1:1:3 C) 1:4:6 D) 5:1:4
13. What is the empirical formula of a compound if a
sample contains 8.52 grams of carbon and 1.42 grams
of hydrogen?
B)
D)
B) CH 2
C) CH
D) C2H2
14. What is the empirical formula of a compound that
contains 28% iron, 24% sulfur, and 48% oxygen by
mass?
A) FeSO 3
C) Fe 2(SO3) 3
B) FeSO 4
D) Fe 2(SO4) 3
15. What is the empirical formula of a compound whose
composition by mass is 50.% sulfur and 50.% oxygen?
A) SO
B) SO 2
C) SO 3
D) S2O3
16. What is the percent composition by mass of sulfur in
the compound MgSO4 (gram-formula mass = 120.
grams per mole)?
A) 20%
B) 27%
C) 46%
D) 53%
-gram
mole
moles
B) 2:1
C) 1:8
D) 8:1
18. Which compound has the smallest percent composition
by mass of chlorine?
A) HCl
8. One mole of O 2 has approximately the same mass as one
mole of
A) CH 4
12. A sample of a compound contains 65.4 grams of zinc,
12.0 grams of carbon, and 48.0 grams of oxygen. What
is the mole ratio of zinc to carbon to oxygen in this
compound?
A) 1:2
C) C2H4 D) C3H6
A) 160 g B) 112 g C) 72 g
B) 24 g C
D) 78 g K
17. What is the ratio by mass of hydrogen to oxygen in H 2
O?
6. Which is an empirical formula?
A) P2O5
A) 23 g Na
C) 42 g Kr
A) C2H
4. Which statement describes the composition of potassium
chlorate, KClO3?
A) C2H2 and CH
C) C4H6 and CH
11. Which sample contains a mole of atoms?
B) KCl
C) LiCl
D) NaCl
19. Base your answer to the following question on the table
below shows the data collected during the heating of a
5.0 gram sample of a hydrated salt.
After 60. minutes, how many grams of water appear to
remain in the salt?
A) 0.00
B) 2.0
C) 1.9
D) 0.90
20. Base your answer to the following question on the information below.
John Dalton, an early scientist, sketched the structure of compounds using his own symbols for the
elements known at the time. Dalton's symbols for four elements and his drawing of potassium
aluminum sulfate are represented by the diagram below.
Today, it is known that the chemical formula for potassium aluminum sulfate is
. It is a hydrated compound because water molecules are included within its
crystal structure. There are 12 moles of H2O for every 1 mole of
. The compound contains
two different positive ions. The gram-formula mass of
is 474 grams per mole.
Show a numerical setup for calculating the percent composition by mass of water in
.
21. Base your answer to the following question on the information below.
Vitamin C, also known as ascorbic acid, is water soluble and cannot be produced by
the human body. Each day, a person's diet should include a source of vitamin C, such as
orange juice. Ascorbic acid has a molecular formula of C6H8O6 and a gram-formula mass of
176 grams per mole.
Show a numerical setup for calculating the percent composition by mass of oxygen in ascorbic acid.