Moles Problem Set

This problem set was developed by S.E. Van Bramer for Chemistry 145 at Widener University.

  1. Styrene is an organic molecule that is used as a building block for many polymers (like polystyrene). The molecular formula for styrene is C8H8.
    1. What is the molecular weight of styrene?

    2. What is the emperical formula of styrene?

    3. How much does 1.000 mole of styrene weigh?

    4. How much does 1.54 pmole of styrene weigh?

    5. How much many moles in 9.67 kg of styrene?

    6. How many moles in 84.6 mg of styrene?

    7. What is the mass percent of carbon in styrene?

    8. What is the mass percent of hydrogen in styrene?

    9. A barrel of an unknown material is recovered from the Delaware river near a plant that produces polystyrene. It has been suggested that the barrel contains styrene. Results from the elemental analysis of an unknown compound are shown below. Does this support the hypothesis that the barrel contains styrene?

      Element Abundance (%)
      Carbon 92.26
      Hydrogen 7.74

    10. Further experimentation determines that the molecular weight of this compound is 78.11 grams per mole. What is the molecular formula for the unknown compound?

Please send comments or suggestions to

Scott Van Bramer
Department of Chemistry
Widener University
Chester, PA 19013

© copyright 1996, S.E. Van Bramer
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Last Updated: Monday, June 24, 1996 7:30:11 PM