Name: ______________________
Class: _________________
Date: _________
ID: A
Unit 5 Moles Assignment #2
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. What information is needed to calculate the percent composition of a compound?
a. the weight of the sample to be analyzed and its density
b. the weight of the sample to be analyzed and its molar volume
c. the formula of the compound and the atomic mass of its elements
d. the formula of the compound and its density
____
2. If 60.2 grams of Hg combines completely with 24.0 grams of Br to form a compound, what is the
percent composition of Hg in the compound?
a. 28.5%
c. 71.5%
b. 39.9%
d. 60.1%
____
3. What is the percent composition of chromium in BaCrO 4 ?
a.
b.
____
c.
d.
20.5%
25.2%
4. What is the percent by mass of carbon in acetone, C 3 H 6 O?
a.
b.
____
4.87%
9.47%
20.7%
62.1%
c.
d.
1.61%
30.0%
5. Which of the following compounds has the highest oxygen content, by weight?
a. Na 2 O
c. BaO
b.
CO 2
d.
H2 O
____
6. The lowest whole-number ratio of the elements in a compound is called the ____.
a. empirical formula
c. binary formula
b. molecular formula
d. representative formula
____
7. Which of the following is NOT an empirical formula?
a. C 2 N 2 H 8
c. BeCr 2 O 7
b.
____
d.
Sb 2 S3
8. Which of the following compounds have the same empirical formula?
a. CO 2 and SO 2
c. C 4 H 10 and C 10 H 4
b.
____
C3 H 8 O
C 7 H 14 and C 10 H 20
d.
C 6 H 12 and C 6 H 14
9. What is the empirical formula of a compound that is 40% sulfur and 60% oxygen by weight?
a. SO
c. SO 3
b.
SO 2
d.
1
S6 O 4
Name: ______________________
ID: A
____ 10. What is the empirical formula of a substance that is 53.5% C, 15.5% H, and 31.1% N by weight?
a. C 3 HN 2
c. C 2 H 8 N
b.
C 4 H 14 N 2
d.
CH 4 N 7
____ 11. The ratio of carbon atoms to hydrogen atoms to oxygen atoms in a molecule of dicyclohexyl maleate is
4 to 6 to 1. What is its molecular formula if its molar mass is 280 g?
a. C 4 H 6 O 1
c. C 12 H 18 O 3
b.
C 8 H 12 O 2
d.
C 16 H 24 O 4
____ 12. Which of the following is NOT true about empirical and molecular formulas?
a. The molecular formula of a compound can be the same as its empirical formula.
b. The molecular formula of a compound can be some whole-number multiple of its
empirical formula.
c. Several compounds can have the same empirical formula, but have different
molecular formulas.
d. The empirical formula of a compound can be triple its molecular formula.
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