Chemistry Flashcard: Percent Composition by Mass

Front

What is percent composition by mass?

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Percent composition by mass is the percentage by mass of each element in a compound, calculated by dividing the mass of the element by the total mass of the compound and multiplying by 100.

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How do you calculate the percent composition of an element in a compound?

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To calculate the percent composition of an element in a compound, use the formula: \( \text{Percent Composition} = \left( \frac{\text{mass of element}}{\text{molar mass of compound}} \right) \times 100 \)

Front

Calculate the percent composition of oxygen in carbon dioxide (CO₂).

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72.7%.

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What is the percent composition by mass of hydrogen in H₂O?

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11.2%.

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What is the percent composition of Benzene, C₆H₆?

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C = 92.2%, H = 7.8%.

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Does carbon or oxygen make up more of the mass in carbon monoxide (CO)?

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Oxygen.

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What is the percent composition of oxygen in sulfuric acid (H₂SO₄)?

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65.3%.

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What is the molar mass of water (H₂O)?

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18.02 g/mol.

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What is the molar mass of carbon dioxide (CO₂)?

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44.01 g/mol.

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What is the molar mass of benzene (C₆H₆)?

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78.11 g/mol.