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Empirical formula calculations: using moles

The starter and exit quiz of the lesson “Empirical formula calculations: using moles”, from the unit “Calculations involving masses” (Year 10 Science) by Oak National Academy.

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12 questions

  1. What is the chemical formula for water?
  2. How many particles are in one mole of any substance?
  3. Calculate the relative formula mass (Mr) of carbon dioxide (CO₂).
  4. If 2 moles of hydrogen gas react with 1 mole of oxygen gas, how many moles of water are produced?
  5. What is the mass (g) of 2 moles of carbon dioxide (CO₂)?
  6. If a compound is made of 30 g of carbon and 70 g of oxygen, what is the percentage by mass of carbon?
  7. Which of the following best describes the term 'empirical formula'?
  8. Write the empirical formula and molecular formula for a compound with a molecular formula of C₆H₁₂O₆.
  9. The empirical formula of a compound is NH₃ and its relative formula mass (Mr) is 34. What is its molecular formula?
  10. True or false? Empirical formula shows the simplest ratio of how many atoms there are of each element in a substance; molecular formula shows the exact numbers of atoms of each element.
  11. Given the following information, calculate the empirical formula of a compound: 2.4 moles of magnesium and 4.8 moles of oxygen.
  12. Given 40 g of carbon reacts with 10 g of hydrogen to form a compound, calculate the empirical formula of the compound. Use the relative atomic masses (Ar): Carbon = 12, Hydrogen = 1.

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Empirical formula calculations: using moles · Examplary