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Worksheets

Empirical and Molecular Formula

Total questions: 121

Worksheet time: 4hrs 58mins

Name
Class
Date
1.
Which pair has the same empirical formula?
a)
NaCrO4 and Na2Cr2O7
b)
C2H4O2 and C6H12O6
c)
C3H6O3 and C2H6O2
d)
CH4 and C2H6
2.
A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?
a)
Mg4N3
b)
MgN2
c)
Mg3N2 
d)
MgN
3.
A formula with the lowest whole # ratio of elements in a compound is called
a)
Molecular Formula
b)
Chemical Formula
c)
Empirical Formula 
d)
Distance Formula
4.
What is the molecular formula if the empirical formula is CH2O and the molecular molar mass is 180.18?
a)
CH2O
b)
C2H4O2
c)
C4H8O4
d)
C6H12O6
5.
What is the molecular formula for a compound with the empirical formula: K2SO4 and a molecular mass of 696g.
a)
K2SO4 
b)
K8SO16
c)
K8S4O8 
d)
K8S4O16 
6.

Given the following: 42.07% Na, 18.89% P, and 39.04% O, determine the empirical formula.

a)

NaPO2

b)

Na2PO3

c)

Na3PO4

d)

NaPO4

7.
A chemical formula that shows the actual # and kinds of atoms present in one molecule of a compound is called_________
a)
ionic formula
b)
covalent formula
c)
empirical formula
d)
molecular formula
8.

When calculating the Empirical formula the mole ratio is given as follows:

H1O3.5

What will the empirical formula be?

a)

H1O3.5

b)

HO3.5

c)

HO4

d)

H2O7

9.

What is the empirical formula if you have 81.82% carbon and 18.18% hydrogen?

a)

C3H8

b)

CH4

c)

C2H2

d)

C4H10

10.
In which compound is the percent composition by mass of Cl equal to 42%?
a)
HClO (gram formula mass = 52 g/mol)
b)
HClO2 (gram formula mass = 68 g/mol)
c)
HClO3 (gram formula mass = 84 g/mol)
d)
HClO4 (gram formula mass = 100 g/mol)
11.
You are given the following percentages: 40.05% S and 59.95% O. Find the empirical formula for these elements.
a)
SO
b)
SO2
c)
SO3
d)
SO4
12.

What is the empirical formula if you have 81.82% carbon and 18.18% hydrogen?

a)

C3H8

b)

CH4

c)

C2H2

d)

C4H10

13.

When calculating the Empirical formula the mole ratio is given as follows:

H1O3.5

What will the empirical formula be?

a)

H1O3.5

b)

HO3.5

c)

HO4

d)

H2O7

14.
Find the percent composition of Cu2S?
a)
%Cu= 67.987 %S= 32.013
b)
%Cu= 79.854   %S= 20.145
c)
%Cu= 35.946   %S= 64.054
15.
Glycerol has a molar mass of 92.09g/mol. Its percent composition is: 39.12% C, 8.75% H, and 51.12% O. What is the molecular formula for glycerol?
a)
C2H3O2
b)
CH2O
c)
C2H4O2
d)
C3H8O3
16.

Epinephrine (adrenaline) is a hormone secreted into the bloodstream in times of stress. It contains 59.0% C, 7.15% H, 26.20%O, 7.65%N and has a molar mass of 183 g/mol. What is its molecular formula?

a)

C9H13NO3

b)

C5H11N3O2

c)

C8H12NO2

d)

C7H9N2O

17.
What is the molecular formula of a compound with an empirical formula of C2OH4 and a molar mass of 88 grams per mole?
a)
C2O4H8
b)
C8O2H4
c)
C4O2H8
d)
C4O8H2
18.
What is the molecular formula if the empirical formula is CH2O and the molecular molar mass is 180.18?
a)
CH2O
b)
C2H4O2
c)
C4H8O4
d)
C6H12O6
19.
What is the molecular formula if the empirical formula is C2H5 and the molecular molar mass is 58.14 g/mol?
a)
C2H5
b)
C4H10
c)
C1H2.5
d)
C4H8
20.

How many elements are in C6H12O6?

a)

1

b)

2

c)

3

d)

4

21.

How many atoms are there total in H2SO4

a)

6

b)

5

c)

7

d)

3

22.
Which is the correct formula for:
 three hydrogen (H)
one sulfur (S)
four oxygen (O)
a)
H3SO4
b)
HSO4
c)
H4S3O
d)
H2O
23.

How many atoms of carbon are in C6H12O6?

a)

3

b)

6

c)

12

d)

24

24.

How many oxygen atoms are in a compound of "liquid paper" (i.e. white out)? TiO2

a)

one

b)

two

c)

three

d)

none

25.

What elements can be found in Aspirin? C9H8O4

a)

carbon

b)

hydrogen

c)

oxygen

d)

helium

26.

Write the empirical formula for: C9H18O3

a)

C2H9O1

b)

C3H6O

c)

C6H15O

d)

C3H3O

27.

Write the empirical formula for: C6H6

a)

CH

b)

C0H0

c)

C0H2

d)

C3H3

28.

Write the empirical formula for: C2H4

a)

CH

b)

C1H4

c)

C0H2

d)

CH2

29.

Is the following formula molecular or empirical?

H2O

a)

molecular

b)

empirical

c)

both

30.

Is the following formula molecular or empirical?

C6H12O6

a)

molecular

b)

empirical

c)

both

31.

Is the following formula molecular or empirical?

H2O2

a)

molecular

b)

empirical

c)

both

32.

Is the following formula molecular or empirical?

CH3

a)

molecular

b)

empirical

c)

both

33.

Define molecular formula.

a)

formula with the lowest whole number ratios of the elements in a compound.

b)

formula for any compound that includes a Nobel gas.

c)

formula for calculating the limiting reagent of a reaction

d)

formula that shows how many of each type of atom are present in a single molecule.

34.

Define empirical formula.

a)

formula with the lowest whole number ratios of the elements in a compound.

b)

formula for any compound that includes a Nobel gas.

c)

formula for calculating the limiting reagent of a reaction

d)

formula that shows how many of each type of atom are present in a single molecule.

35.
Which of the following is considered an empirical formula?
a)
CH3COOH
b)
C6H12O6
c)
H2O
36.

Which of the following is considered an empirical formula?

a)

CH3COOH

b)

C6H12O6

c)

H2O

d)

Mg2Cl4

37.

Which pair of molecules would have the same empirical formula?

a)

NaCrO4 and Na2Cr2O7

b)

C2H4O2 and C6H12O6

c)

C3H6O3 and C2H6O2

d)

CH4 and C2H6

38.

Basic aluminium diacetate – Its molecular formula is HOAl(CH3CO2)2 How many total atoms are in this molecule?

a)

4

b)

12

c)

17

d)

20

39.

Find the empirical formula for a compound which contains 32.8% chromium and 67.2% chlorine.

a)

CrCl

b)

CrCl3

c)

Cr3Cl

d)

Cr2Cl6

40.

A compound contains 18.8% Na, 29.0% Cl, and 52.5% O by mass. Determine the empirical formula.

a)

NaClO

b)

NaClO4

c)

Na2Cl2O8

d)

NaCl2O4

41.
Which of the following is considered an empirical formula?
a)
CH3COOH
b)
C6H12O6
c)
H2O
42.

A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?

a)

Mg4N3

b)

MgN2

c)

Mg3N2

d)

MgN

43.

---------and ---------, have the same empirical formula (CH).

a)

C2H2 and C6H6

b)

CH4 and CH6

c)

NO2 and NO3

d)

NH3 and N2H4

44.

How many Carbons "C" are in C18H34O3

a)

18

b)

34

c)

3

d)

37

45.
A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?
a)
Mg4N3
b)
MgN2
c)
Mg3N2 
d)
MgN
46.

Molecular Formula = C2F6

Choose the correct empirical formula.

a)

CF

b)

C2F6

c)

C3F

d)

CF3

47.
Which pair has the same empirical formula?
a)
NaCrO4 and Na2Cr2O7
b)
C2H4O2 and C6H12O6
c)
C3H6O3 and C2H6O2
d)
CH4 and C2H6
48.

Empirical Formula = CF2

Molecular formula mass = 192 g/mol

Molecular Formula = ?

a)

C4F8

b)

C8F4

c)

C3F6

d)

C2F4

49.
What is the empirical formula if you have 81.82% carbon and 18.18% hydrogen?
a)
C3H8
b)
CH4
c)
C2H2
d)
C4H10
50.

What is the molecular formula for a compound with the empirical formula: K2SO4 and a molecular mass of 696g.

a)

K2SO4

b)

K8SO16

c)

K8S4O8

d)

K8S4O16

51.

A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?

a)

Mg4N3

b)

MgN2

c)

Mg3N2

d)

MgN

52.

Given the following: 42.07g Na, 18.89g P, and 39.04g O, determine the empirical formula.

a)

NaPO2

b)

Na2PO3

c)

Na3PO4

d)

NaPO4

53.

The empirical formula of a substance is CH2O. The molar mass is 180g/mol. What is the molecular formula?

a)

CH2O

b)

C3H6O3

c)

C6H12O6

d)

C12H6O12

54.
What is the molecular formula if the empirical formula is C2H5 and the molecular molar mass is 58.14 g/mol?
a)
C2H5
b)
C4H10
c)
C1H2.5
d)
C4H8
55.

What is the empirical formula of K2SO4?

a)

K2SO4

b)

KSO2

c)

K2SO2

d)

KSO8

56.

Which of the following could be a molecular formula with the empirical formula of CH2O?

a)

CH2O2

b)

CHO

c)

C3H5O3

d)

C2H4O2

57.

Which of these is NOT an empirical formula?

a)

CH2

b)

C2H5

c)

C6H4

d)

C3H7

e)

C5H17

58.
Which one is an empirical formula?
a)
H2O2
b)
C2H6O12
c)
CaCl2
d)
N2O8
59.
What is the percent by mass of oxygen in MgO?
a)
20%
b)
40%
c)
50%
d)
60%
60.
What is the molecular formula if the empirical formula is CH2O and the molecular molar mass is 180.18?
a)
CH2O
b)
C2H4O2
c)
C4H8O4
d)
C6H12O6
61.
Which pair has the same empirical formula?
a)
NaCrO4 and Na2Cr2O7
b)
C2H4O2 and C6H12O6
c)
C3H6O3 and C2H6O2
d)
CH4 and C2H6
62.

How many Carbons "C" are in C18H34O3

a)

18

b)

34

c)

3

d)

37

63.

How many "C" are in CO2

a)

2

b)

1

c)

0

d)

3

64.
What is the best definition for subscript?
 
a)
The big number that tells you the number of molecules.
b)
The atomic number
c)
The little number that tells the number of atoms for each element.
65.
A chemical formula that shows the actual # and kinds of atoms present in one molecule of a compound is called_________
a)
ionic formula
b)
covalent formula
c)
empirical formula
d)
molecular formula
66.

C2F6

Choose the correct empirical formula...

a)

CF

b)

C2F6

c)

C6F2

d)

CF3

67.

What is the empirical formula for N2S3?

a)

NS

b)

N3S2

c)

N2S3

d)

N1S1.5

68.

Si2F6

Choose the correct empirical formula...

a)

SiF

b)

Si2F6

c)

SiF3

d)

Si6F2

69.
A formula with the lowest whole # ratio of elements in a compound is called
a)
Molecular Formula
b)
Chemical Formula
c)
Empirical Formula 
d)
Distance Formula
70.
A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?
a)
Mg4N3
b)
MgN2
c)
Mg3N2 
d)
MgN
71.
You are given the following percentages: 40.05% S and 59.95% O. Find the empirical formula for these elements.
a)
SO
b)
SO2
c)
SO3
d)
SO4
72.
Given the following: 42.07% Na, 18.89% P, and 39.04% O, determine the empirical formula.
a)
 NaPO2
b)
Na2PO3
c)
Na3PO4
d)
NaPO4
73.
What is the molecular formula for a compound with the empirical formula: K2SO4 and a molecular mass of 696g.
a)
K2SO4 
b)
K8SO16
c)
K8S4O8 
d)
K8S4O16 
74.
What is the percent by mass of sodium in NaCl?
a)
39%
b)
61%
c)
35%
d)
65%
75.

P3O4

a)

PO

b)

P3O4

c)

P4O3

76.

C2H6O

a)

CHO

b)

C2H6O

77.

S2O8

a)

S2O8

b)

SO

c)

SO4

d)

S8O2

78.

Hg2Br2

a)

HgBr

b)

Hg2Br2

79.

N2S3

a)

NS

b)

N3S2

c)

N2S3

80.

Br2O6

a)

BrO3

b)

Br6O2

c)

BrO

d)

Br2O6

81.

C4H6

a)

CH

b)

CH3

c)

C2H3

d)

C4H6

82.
Glycerol has a molar mass of 92.09g/mol. Its percent composition is: 39.12% C, 8.75% H, and 51.12% O. What is the molecular formula for glycerol?
a)
C2H3O2
b)
CH2O
c)
C2H4O2
d)
C3H8O3
83.
Which pair has the same empirical formula?
a)
NaCrO4 and Na2Cr2O7
b)
C2H4O2 and C6H12O6
c)
C3H6O3 and C2H6O2
d)
CH4 and C2H6
84.
What is the empirical formula if you have 81.82% carbon and 18.18% hydrogen?
a)
C3H8
b)
CH4
c)
C2H2
d)
C4H10
85.
Given the following: 42.07% Na, 18.89% P, and 39.04% O, determine the empirical formula.
a)
 NaPO2
b)
Na2PO3
c)
Na3PO4
d)
NaPO4
86.
What is the molecular formula if the empirical formula is CH2O and the molecular molar mass is 180.18?
a)
CH2O
b)
C2H4O2
c)
C4H8O4
d)
C6H12O6
87.
A formula with the lowest whole # ratio of elements in a compound is called
a)
Molecular Formula
b)
Chemical Formula
c)
Empirical Formula 
d)
Distance Formula
88.
You are given the following percentages: 40.05% S and 59.95% O. Find the empirical formula for these elements.
a)
SO
b)
SO2
c)
SO3
d)
SO4
89.
A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?
a)
Mg4N3
b)
MgN2
c)
Mg3N2 
d)
MgN
90.

What is the empirical formula if you have 36.84% nitrogen and 63.16% oxygen?

a)

NO

b)

N2O4

c)

N2O3

d)

N2O5

91.

A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?

a)

Mg4N3

b)

MgN2

c)

Mg3N2

d)

MgN

92.

Calculate the molar mass of water (H2O).

a)

10 g/mol

b)

17 g/mol

c)

18 g/mol

d)

34 g/mol

93.

What is the empirical formula for N2S3?

a)

NS

b)

N3S2

c)

N2S3

d)

N1S1.5

94.
Molar mass is in units of ________.
a)
grams
b)
grams/mole
c)
mole
d)
moles/gram
95.

Which of these is NOT an empirical formula?

a)

CH2

b)

C2H5

c)

C6H4

d)

C3H7

e)

C5H17

96.

Glucose has the formula C6H12O6. Maltose has the chemical formula C12H22O11. Do the have the same empirical formula?

a)

Yes

b)

No

97.

What is the empirical formula for hydrogen peroxide (H2O2)?

a)

H2O

b)

H2O2

c)

HO

d)

HO2

98.
Which pair has the same empirical formula?
a)
NaCrO4 and Na2Cr2O7
b)
C2H4O2 and C6H12O6
c)
C3H6O3 and C2H6O2
d)
CH4 and C2H6
99.
What is the empirical formula for the following:
Pb5Cr5O20
a)
Pb2Cr2O10
b)
PbCr2O7
c)
Pb9Cr4O2
d)
PbCrO4
100.
What is the empirical formula of the following molecular formula:  C3H6
a)
C3H6
b)
CH2
c)
C2H4
d)
CH3
101.
A formula with the lowest whole # ratio of elements in a compound is called
a)
Molecular Formula
b)
Chemical Formula
c)
Empirical Formula 
d)
Distance Formula
102.

What is the empirical formula for N2S3?

a)

NS

b)

N3S2

c)

N2S3

d)

N1S1.5

103.

Which of these is NOT an empirical formula?

a)

CH2

b)

C2H5

c)

C6H4

d)

C3H7

e)

C5H17

104.

Glucose has the formula C6H12O6. Maltose has the chemical formula C12H22O11. Do the have the same empirical formula?

a)

Yes

b)

No

105.

Napthalene has the chemical formula C10H8. What would be the empirical formula?

a)

C10H8

b)

C5H4

c)

C20H16

d)

CH2

e)

C4H3

106.

What is the empirical formula for hydrogen peroxide (H2O2)?

a)

H2O

b)

H2O2

c)

HO

d)

HO2

107.
Which of the following is considered an empirical formula?
a)
CH3COOH
b)
C6H12O6
c)
H2O
108.
What is the empirical formula if you have 81.82% carbon and 18.18% hydrogen?
a)

C3H8

b)

CH4

c)

C2H2

d)

C4H10

109.
A formula with the lowest whole # ratio of elements in a compound is called
a)
Molecular Formula
b)
Chemical Formula
c)
Empirical Formula 
d)
Distance Formula
110.
A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?
a)
Mg4N3
b)
MgN2
c)
Mg3N2 
d)
MgN
111.

Which pair has the same compound, empirical & molecular formula?

a)
NaCrO4 and Na2Cr2O7
b)
C2H4O2 and C6H12O6
c)
C3H6O3 and C2H6O2
d)
CH4 and C2H6
112.
Given the following: 42.07% Na, 18.89% P, and 39.04% O, determine the empirical formula.
a)
NaPO2
b)
Na2PO3
c)
Na3PO4
d)
NaPO4
113.
Whats the empirical formula of a molecule containing 18.7% of Lithium, 16.3% of Carbon and 65.0% of oxygen?
a)
CO2Li3
b)
Li2CO3
c)
Li3CO2
d)
LiCO5
114.
Calculate the number of atoms in 0.0340 g Zn.
a)
5.200 x 10-4 atoms Zn
b)
3.130 x 1023 atoms Zn
c)
3.130 x 1020 atoms Zn
d)
1 atom Zn
115.
What is the molecular formula for a compound with the empirical formula: K2SO4 and a molecular mass of 696g.
a)
K2SO4 
b)
K8SO16
c)
K8S4O8 
d)
K8S4O16 
116.
A chemical formula that shows the actual # and kinds of atoms present in one molecule of a compound is called_________
a)
ionic formula
b)
covalent formula
c)
empirical formula
d)
molecular formula
117.
An empirical formula:
a)
is a formula that calculates the coefficients of a compound in a balanced equation.
b)
is the simplest whole-number ratio of moles of elements in the compound.
118.
Which pair has the same empirical formula?
a)
NaCrO4 and Na2Cr2O7
b)
C2H4O2 and C6H12O6
c)
C3H6O3 and C2H6O2
d)
CH4 and C2H6
119.
What is the percent by mass of fluorine in CaF2 (gram-formula mass = 78 g/mol)?
a)
24%
b)
49%
c)
51%
d)
65%
120.
What is the percent by mass of sodium in NaCl?
a)
39%
b)
61%
c)
35%
d)
65%
121.
What is the percent by mass of oxygen in MgO?
a)
20%
b)
40%
c)
50%
d)
60%

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