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Worksheets

Empirical & Molecular

Total questions: 27

Worksheet time: 2hrs 57mins

Name
Class
Date
1.
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
2.

What is the empirical formula for N2S3?

a)

NS

b)

N3S2

c)

N2S3

d)

N1S1.5

3.

What is the empirical formula for C4H6?

a)

CH

b)

CH3

c)

C2H3

d)

C4H6

4.

Which pair has the same empirical formula?

a)

NaCrO4 and Na2Cr2O7

b)

C2H4O2 and C6H12O6

c)

C3H6O3 and C2H6O2

d)

CH4 and C2H6

5.

You are given 40.05g S and 59.95g O. Find the empirical formula for these elements.

a)

SO

b)

SO2

c)

SO3

d)

SO4

6.

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

7.

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

8.

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

a)

C3H8

b)

CH3

c)

C2H2

d)

C4H10

9.

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

10.

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

11.

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

a)

C3H8

b)

CH4

c)

C2H2

d)

C4H10

12.

Molecular Formula = Si2F6

Choose the correct empirical formula.

a)

SiF

b)

Si2F6

c)

SiF3

d)

Si4F12

13.

Molecular Formula = C2F6

Choose the correct empirical formula.

a)

CF

b)

C2F6

c)

C3F

d)

CF3

14.

A compound is made up of 40% calcium(Ca) and 60% chlorine(Cl) by mass. What is the empirical formula of the compound?

a)

CaCl

b)

CaCl2

c)

Ca2Cl

d)

Ca2Cl3

15.

What is the percent composition by mass of carbon in carbon dioxide ( CO2CO_2 )?

a)

27.3%

b)

42.9%

c)

57.1%

d)

72.7%

16.

If a compound sample contains 40g of calcium, 12g of carbon, and 48g of oxygen, what is the percent composition by mass of calcium?

a)

40%

b)

50%

c)

60%

d)

70%

17.

What is the percent composition by mass of oxygen in water ( H2OH_2O )?

a)

11%

b)

89%

c)

67%

d)

33%

18.

A compound contains 24g of carbon, 4g of hydrogen, and 32g of oxygen. What is the percent composition by mass of hydrogen?

a)

4%

b)

7%

c)

12%

d)

14%

19.

If a sample has a mass of 58.5 grams and is composed of 39.3 g of Na, 18.6 g of C, and 0.6 g of H, what is the percent composition by mass of carbon?

a)

31.8%

b)

33.3%

c)

35.7%

d)

37.6%

20.

What is the empirical formula for the following:
Pb5Cr5O20

a)

Pb2Cr2O10

b)

PbCr2O7

c)

Pb9Cr4O2

d)

PbCrO4

21.

What is the molecular formula if the empirical formula is CH2O and the molecular molar mass is 180.18?

(C = 12.01 g/mol, H = 1.01 g/mol, O = 16.00 g/mol)

a)

CH2O

b)

C2H4O2

c)

C4H8O4

d)

C6H12O6

22.

What is the percent composition of Benzene, C6H6?

a)

C = 50%
H = 50%

b)

C = 85.7 %
H = 14.3%

c)

C = 92.2%
H = 7.8%

d)

C = 71.9%
H = 28.1%

23.

If you have 250g of Carbon Dioxide (CO2) how many grams of Carbon would you have?

a)

136.5 g

b)

68.3 g

c)

27.3g

d)

181.7g

24.

Find the empirical formula of a compound that is 53.7% iron and 46.3% sulfur.


a)

FeS

b)

Fe2S3

c)

Fe4 S6

25.

The molar mass of a compound is 92 g/mol.  Analysis of the sample indicates that it contains 0.606 g N and 1.390 g O.  Find the compound’s molecular formula.


a)

NO

b)

NO2

c)

N2O4

26.

What has greatest amount of Fe? FeCl2 or FeI2

a)

FeI2

b)

FeCl2

c)

Same amount

27.

Which compound contains more moles of Fe per mole of compound? Fe2O3 or Fe3O4


a)

Fe2O3

b)

Fe3O4

c)

Both contain the same