Percent Composition by Mass Worksheet
A Grade 11 Chemistry worksheet focusing on calculating percent composition by mass for various chemical compounds.
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Percent Composition by Mass
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Read each question carefully and calculate the percent composition by mass for the indicated elements in the given compounds. Show all your work.
1. The formula for calculating percent composition by mass is (mass of element / ) x 100%.
2. The molar mass of a compound is the sum of the atomic masses of all atoms in its .
3. Calculate the percent composition by mass of carbon in C₆H₁₂O₆ (glucose).
4. Determine the percent composition by mass of oxygen in H₂SO₄ (sulfuric acid).
5. Which of the following compounds has the highest percent composition by mass of nitrogen?
NH₃
N₂O
NO₂
N₂O₄
Match the compound with the approximate percent composition by mass of the indicated element.
6. NaCl (% Na)
a. 39.3%
7. KCl (% K)
b. 60.7%
8. H₂O (% O)
c. 88.8%
9. A compound is found to contain 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. If the molar mass of the compound is approximately 180 g/mol, what is the molecular formula of the compound?