The Mole
Practice Test
1.
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
3
c.
CH
2
d.
CH
2.
Determine the number of atoms in 3.54 mol S.
a.
2.13 x 10
24
b.
1.70 x 10
24
c.
1.70 x 10
23
d.
2.13 x 10
23
3.
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.
Fe
3
O
4
b.
Fe
2
O
3
c.
FeO
d.
FeO
2
4.
How many moles of hydrogen are present in 2.0 grams of hydrogen gas?
a.
1.0 mol
b.
2.0 mol
c.
4.0 mol
d.
0.5 mol
5.
How many particles are present in one mole of particles?
a.
6.02 x 10
23
b.
12
c.
1
d.
3.0 x 10
8
6.
How many atoms of carbon are in a pure sample of carbon having a mass of 72.0 g?
Element
Molar Mass (g/mol)
Hydrogen
1.01
Carbon
12.01
Chlorine
35.45
a.
3.6 x 10
23
b.
36 x 10
24
c.
3.6 x 10
24
d.
4.33 x 10
25
7.
What is the molar mass of H
2
CrO
4
?
a.
118 g
b.
52 g
c.
64 g
d.
2 g
8.
How can the actual molecular formula be determined?
a.
from the molar mass divided by the mass of the empirical formula
b.
from the empirical formula alone
c.
from the molar mass multiplied by the mass of the empirical formula
d.
from the molar mass alone
9.
What is the correct chemical formula for barium hydroxide octahydrate?
Prefix
Molecules H
2
O
Mono-
1
Di-
2
Tri-
3
Tetra-
4
Penta-
5
Hexa-
6
Hepta-
7
Octa-
8
Deca-
10
a.
Ba(OH)
2
. H
2
O
b.
8Ba(OH)
2
. H
2
O
c.
Ba . 8(OH)
2
d.
Ba(OH)
2
. 8H
2
O
10.
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.
2 units
d.
0.5 unit
11.
Calculate the number of moles of hydrogen atoms in 4.75 mol sulfuric acid.
a.
4.75 mol
b.
33.2 mol
c.
9.50 mol
d.
2.38 mol
12.
Which word indicates that two water molecules are associated with a substance in a chemical compound?
a.
mono
-
b.
di
-
c.
an
-
d.
tri
-
13.
A compound that has a specific number of water molecules bound to the structure is ______________?
a.
a hydrate
b.
waterlogged
c.
an anhydrate
d.
aqueous
14.
What is the SI base unit used to measure the amount of a substance?
a.
kelvin
b.
meter
c.
kilogram
d.
mole
15.
What is the mass of one mole of carbon-12 atoms?
a.
6 amu
b.
6 grams
c.
12 grams
d.
12 amu
16.
What relationship is described by the formula below? (mass of the element/mass of the compound) x 100
a.
Avogadro’s number
b.
mole ratio
c.
empirical formula
d.
percent composition
17.
How many molecules of ammonia are present in 34.0 g of ammonia NH(
3
)?
a.
1.77 x 10
22
b.
6.02 x 10
23
c.
1.20 x 10
24
d.
34
