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Molar Mass and Percent Composition

Total questions: 15

Worksheet time: 54mins

Name
Class
Date
1.

Find the percentage composition of Mg in Mg3(PO4)2.


a)

27.48% Mg

b)

43.11% Mg

c)

16.00% Mg

d)

12.63% Mg

2.

What is the molar mass of CO2?

a)

12 g/mol

b)

16 g/mol

c)

32 g/mol

d)

44 g/mol

3.

Calculate the molar mass of Ba(C2H3O2)2

a)

255.3 g/mol

b)

237.3 g/mol

c)

228.3 g/mol

d)

196.3 g/mol

4.
What are the units in molar mass?
a)
grams
b)
moles
c)
moles/gram
d)
grams/mole
5.
Which list of number of atoms in Mg(NO3)2 is right?
a)
Mg : 1--NO :  6
b)
Mg : 1-- N :  6--O:  6
c)
Mg :  1-- N:   1--  O: 5
d)
Mg :  1-- N: 2--  O: 6
6.

Calculate the molar mass of Ba(C2H3O2)2

a)

255.3 g/mol

b)

237.3 g/mol

c)

228.3 g/mol

d)

196.3 g/mol

7.

The mass % of H in methane (CH4) is:

a)

75%

b)

92%

c)

25%

d)

4%

e)

6%

8.

Gallium nitride (GaN) is an important material in computer chips. What is the percent composition of gallium in gallium nitride?

a)

83%

b)

17%

c)

100%

d)

0.8327

9.
What is the molar mass of AuCl3?
a)
96 g
b)
130 g
c)
232.5 g
d)
303.3 g
10.

Calculate the molar mass of Cu2O.

a)

37 g/mol

b)

45 g/mol

c)

79.5 g/mol

d)

143 g/mol

11.

Calculate the molar mass of NH4NO2

a)

50 g/mol

b)

60 g/mol

c)

64 g/mol

d)

78 g/mol

12.
What is the percentage of chromium in K2Cr2O7?
a)
38.1%
b)
27.2%
c)
34.7%
d)
100%
13.
What is the molar mass of PbSO4
a)
303.3 g/mol
b)
294.7g/mol
c)
163.8g/mol
d)
372g/mol
14.
What is the molar mass C6H12O6
a)
61.0g/mol
b)
95.7g/mol
c)
180.2 g/mol
d)
164.9g/mol
15.
What is the percent composition by mass of sulfur in the compound MgSO4 (gram formula mass = 120 g/mol)?
a)
20%
b)
27%
c)
46%
d)
53%