Chapter 11:
The Mole
Practice Test
1.
An empirical formula mass is found to be 17 g/mol. The molar mass is found to be 34 g/mol. What is the number of empirical formula units in this molar mass?
a.
1 unit
b.
17 units
c.
0.5 unit
d.
2 units
Hint
2.
How many molecules of ammonia are present in 34.0 g of ammonia NH
(3)
?
a.
1.20 × 10
24
b.
34
c.
1.77 × 10
22
d.
6.02 × 10
23
Hint
3.
Calculate the number of atoms in 4.00 × 10
-5
g sodium.
a.
1.05 × 10
18
atoms
b.
3.24 × 10
23
atoms
c.
3.92 × 10
19
atoms
d.
5.54 × 10
20
atoms
Hint
4.
How many moles of hydrogen atoms are present in 2.0 moles of ammonia NH
(3)
?
a.
2.0 mol
b.
6.0 mol
c.
3.0 mol
d.
8.0 mol
Hint
5.
A compound that has a specific number of water molecules bound to the structure is ______________?
a.
aqueous
b.
an anhydrate
c.
waterlogged
d.
a hydrate
Hint
6.
How many moles of hydrogen are present in 2.0 grams of hydrogen gas?
a.
2.0 mol
b.
4.0 mol
c.
1.0 mol
d.
0.5 mol
Hint
7.
What is the mass of 5.0 × 10
21
molecules of water?
a.
5.0 g
b.
8.3 x 10
-3
g
c.
0.15 g
d.
6.02 x 10
23
g
Hint
8.
A 4.628-g sample of an iron oxide was found to contain 3.348 g of iron and 1.280 g of oxygen. What is the simplest formula for this compound?
a.
FeO
2
b.
Fe
2
O
3
c.
FeO
d.
Fe
3
O
4
Hint
9.
What is the mass of 1.0 × 10
12
molecules of O
2
?
a.
6.0 × 10
11
g
b.
5.3 × 10
-11
g
c.
1.9 × 10
13
g
d.
2.7 × 10
-11
g
Hint
10.
What mass of calcium metal could be obtained from 1 kg of limestone that is 50.0% pure CaCO
3
?
a.
0.4 kg
b.
0.2 kg
c.
0.5 kg
d.
0.05 kg
Hint
11.
What is the mass of one mole of carbon-12 atoms?
a.
12 amu
b.
6 amu
c.
12 grams
d.
6 grams
Hint
12.
A compound contains sulfur, oxygen, and chlorine. Analysis of a sample showed that it contained by mass 26.95% sulfur and 59.61% chlorine. What is the simplest formula for this compound?
a.
SOCl
2
.
b.
SO
2
Cl
2
.
c.
SOCl
d.
SO
2
Cl
Hint
13.
What relationship is described by the formula below?
(mass of the element/mass of the compound) × 100
a.
empirical formula
b.
Avogadro’s number
c.
percent composition
d.
mole ratio
Hint
14.
How many moles of atoms are present in one mole of water?
a.
6 mol
b.
1 mol
c.
3 mol
d.
2 mol
Hint
15.
What mass of iron is contained in 62.8 grams of pyrite FeS
(2)
?
a.
31.7 g
b.
58.5 g
c.
29.2 g
d.
40.3 g
Hint
16.
What is the SI base unit used to measure the amount of a substance?
a.
mole
b.
meter
c.
kelvin
d.
kilogram
Hint
17.
Analysis of a covalent compound showed that it contained 14.4% hydrogen and 85.6% carbon by mass. What is the empirical formula for this compound?
a.
C
2
H
3
b.
CH
2
c.
CH
d.
CH
2
Hint
18.
What is the molar mass of H
2
CrO
4
?
a.
64 g
b.
118 g
c.
2 g
d.
52 g
Hint
19.
How many moles of C
3
H
8
are present in 451 g C
3
H
8
?
a.
10.2 mol
b.
3.84 mol
c.
0.879 mol
d.
1.44 mol
Hint
20.
How is one gram defined?
a.
0.1 mole of amu
b.
one mole of amu
c.
one mole of protons
d.
10 moles of amu
Hint
