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WorksheetsEmpirical/Molecular Formulas and Percent Composition
Total questions: 10
Worksheet time: 30mins
An empirical formula shows the...
lowest whole number ratio of elements in a compound
actual number of each element in a compound
number of valence electrons in a compound
number of protons in a compound
Which of the following is an empirical formula?
H2O2
C6H12O6
NO2
P2O4
For what type of compound is the molecular formula usually equal to the empirical formula?
ionic
covalent
What is the molecular formula of a compound with an empirical formula of CH2 and a molar mass of 70.15 g/mol?
C3H6
C5H10
C2H4
CH4
How many of each element are in Al2(CO3)3?
Al = 2; C = 1; O = 3
Al = 2; C = 3; O = 9
Al = 2; C = 1; O = 9
Al = 2; C = 4; O = 6
What is the molar mass of CH4?
10.0 g/mol
13.02 g/mol
16.05 g/mol
5.0 g/mol
What is the percent of carbon in CH4 by mass? (HINT: use the molar mass from the last question)
74.8%
37.4%
25.2%
20.0%
What do chemists call an ionic compound that has water attached to it?
hydronium
hydroxide
hydrophobic
hydrate
Which of the following would give you the molar mass of AlCl3 * 6 H2O?
26.98 + (3 x 35.45) - (6 x 18.02)
26.98 + (3 x 35.45) + (6 x 18.02)
26.98 + 35.45 + 18.02
26.98 + (3 x 35.45) x (6 x 18.02)
The molar mass of CoCl2 * 6 H2O is 237.95 g/mol. Which of the following would give you the percent water by mass?
[(6 x 18.02) / 237.95] x 100
[(6 + 18.02) / 237.95] x 100
(237.95 / 18.02) x 100
(18.02 / 237.95) x 100
