Transcript Percent Composition - Jefferson Forest High School

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The Law of Definite Proportions states that a
compound is always comprised of the same
atoms in the same ratio, or percentage.
◦ In order to determine the percentages, we use
molar mass
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Percent composition gives you the ratio of the
mass of one element to all the other elements
that make up a unique compound.
◦ Methane, CH4, is comprised of 1 atom of carbon and 4
atoms of hydrogen.
◦ The molar mass of methane is 16.04 g/mol
◦ Carbon contributes a total mass of 12.01 g/mol
◦ All Hydrogen atoms together contribute 4.03 g/mol
◦ The ratio of C:CH4 is 12.01:16.04 or 74.88%
◦ The ratio of H:CH4 is 4.03:16.04 or 25.12%
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So therefore, the percent composition of
methane is 74.88% Carbon and 25.12% Hydrogen
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5.
Calculate the % composition of Fe3C, a
compound used to cast iron.
Calculate the % composition of sulfur
dioxide.
Calculate the % composition of ammonium
nitrate.
Calculate the percent composition of
glucose, C6H12O6.
Calculate the percent composition of acetic
acid, CH3COOH.
Calculate the % composition of Fe3C, a
compound used to cast iron.
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Fe = 55.85 g/mol x 3 = 167.6 g/mol
C = 12.01 g/mol
Fe3C = 167.6 g/mol + 12.01 g/mol = 179.6 g/mol
% Fe = 167.6 g/mol / 179.6 g/mol x 100 = 93.32%
% C = 12.01 g/mol / 179.6 g/mol x 100 = 6.69%
93.32% Fe, 6.69% C
50.05% S, 49.95% O
35.00% N, 5.05% H, 59.96% O (p.s. the
formula is NH4NO3)
39.99% C, 6.73% H, 53.28% O
39.99% C, 6.73% H, 53.28% O !!!!
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What is the empirical formula for each?!!!
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Worksheet