The percentage by mass of carbon in carbon dioxide, CO2, is about
Correct answer: A. 27.3 per cent
- A. 27.3 per cent
- B. 12 per cent
- C. 44 per cent
- D. 72.7 per cent
Explanation
The molar mass is 12 + 32, that is 44, so the carbon fraction is 12 divided by 44 multiplied by 100, giving 27.3 per cent. The figure 72.7 per cent is the oxygen content, which is why it appears as a distractor, and the two must add to 100. Percentage composition is the first step in working out an empirical formula from experimental data.
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About Moles and Avogadro's Number
The mole connects the microscopic number of particles with measurable mass, using Avogadro's number, 6.022 × 10²³ particles per mole. Questions involve molar mass, conversion between mass, moles and particles, percentage composition, empirical and molecular formulas, and distinguishing atoms, molecules, ions and formula units.
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