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WorksheetsChemistry Calculate Percent Composition
Total questions: 29
Worksheet time: 4hrs 49mins
Name
Class
Date
1.
What is the percent by mass of magnesium in MgO?
a)
20%
b)
40%
c)
50%
d)
60%
2.
What is the percent by mass of sodium in NaCl?
a)
39%
b)
61%
c)
35%
d)
65%
3.
What is the percent by mass of chlorine in NaCl?
a)
39%
b)
61%
c)
35%
d)
65%
4.
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%
5.
What is the percent composition by mass of magnesium in the compound MgSO4 (gram formula mass = 120 g/mol)?
a)
20%
b)
27%
c)
46%
d)
53%
6.
What is the percent by mass of oxygen in MgO?
a)
20%
b)
40%
c)
50%
d)
60%
7.
What is the percent by mass of fluorine in CaF2 (gram-formula mass = 78 g/mol)?
a)
24%
b)
49%
c)
51%
d)
65%
8.
What is the percent by mass of calcium in CaF2 (gram-formula mass = 78 g/mol)?
a)
24%
b)
49%
c)
51%
d)
65%
9.
How many molecules are there in 0.04 moles of CaF?
a)
2.4 x 1023
b)
2.4 x 1022
c)
2.36
d)
1450
10.
What is the percent composition on Oxygen in NO2? (rounded)
a)
40%
b)
50%
c)
60%
d)
70%
11.
Which of the following is NOT needed to calculate percent composition?
a)
Mass of specific element
b)
Molar Mass
c)
Avogadro's Number
d)
Division
12.
Find the percent composition of Cu in CuBr2 .
a)
28.45%
b)
32.85%
c)
17.78%
d)
68.10%
13.
What is the percent composition of S in the formula (NH4)2S ?
a)
12.05%
b)
19.30%
c)
47.11%
d)
56.18%
14.
You are given the following percentages: 40.05% S and 59.95% O. Find the empirical formula for these elements. (keep two decimal places throughout calculations)
a)
SO
b)
SO2
c)
SO3
d)
SO4
15.
What is the empirical formula if you have 88.80% copper and 11.20% oxygen?
a)
Cu3O8
b)
CuO4
c)
Cu2O
d)
Cu4O10
16.
What is the empirical formula for the following molecular formula: C6H14
a)
C6H14
b)
C3H7
c)
CH2
d)
CH3
17.
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
18.
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
19.
What is the empirical formula for the following:
C3H8O
C3H8O
a)
C1.5H4O0.5
b)
C3H8O
c)
C6H16O2
d)
C3H2O
20.
What is the empirical formula for the following:
Pb5Cr5O20
Pb5Cr5O20
a)
Pb2Cr2O10
b)
PbCr2O7
c)
Pb9Cr4O2
d)
PbCrO4
21.
What is the percent composition of Benzene, C6H6?
a)
C = 50%
H = 50%
H = 50%
b)
C = 85.7 %
H = 14.3%
H = 14.3%
c)
C = 92.2%
H = 7.8%
H = 7.8%
d)
C = 71.9%
H = 28.1%
H = 28.1%
22.
What is the percent composition of water?
a)
H = 11.1%
O = 89.9%
O = 89.9%
b)
H = 66.7%
O = 33.3%
O = 33.3%
c)
H = 5.6%
O = 89.9%
O = 89.9%
d)
H = 20%
O = 80%
O = 80%
23.
An 8 g sample of a compound is found to be 3.766 g Aluminum & 4.234 g Oxygen. What is it's empirical formula?
a)
Al2O3
b)
AlO2
c)
Al2O
d)
Al3O2
24.
What is the empirical formula of the following molecular formula: C3H6
a)
C3H6
b)
CH2
c)
C2H4
d)
CH3
25.
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
26.
What is the empirical formula for the following molecular formula: C6H14
a)
C6H14
b)
C3H7
c)
CH2
d)
CH3
27.
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
28.
What is the empirical formula for the following molecular formula: C5H12
a)
C5H12
b)
CH3
c)
CH2
d)
C2.5H6
29.
Which pair has the same empirical formula?
a)
NaCrO4 and Na2Cr2O7
b)
C2H4O2 and C6H12O6
c)
C3H6O3 and C2H6O2
d)
CH4 and C2H6
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