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Constructed Response . Topic 7: Solutions

Set H: Solubility, type of solution, part per million calculation

Base your answers to questions 27 through 30 on the information below.

Scientists who study aquatic ecosystems are often interested in the concentration of dissolved

oxyge n in water. Oxygen, O2, has a very low solubility in water, and therefore its solubility is
usuall y expressed in units of milligrams per 1000. grams of water at 1.0 atmosphere pressure. The

graph below shows a solubility curve of oxygen in water.

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27. A student determines that 8.2 milligrams of oxygen is 27.

o
dis solved in a 1000. gram sample of water at 15 C and
1.0 atmosphere of pressure. In terms of saturation, what
typ e of solution is this sample?

28. Explain, in terms of molecular polarity, why oxygen gas 28.
has a low solubility in water. Your response must include

both oxygen and water?

29. A student prepared a solution of oxygen by dissolving 6.0 mg 29.
o
of oxygen in 1000 gram of water at 20 C. Determine how

many more milligram of oxygen must be added to the
solution to make it a saturated solution.

30. An aqueous solution has 0.007 gram of oxygen dissolved in 30.
100 0 grams of water. In the space to the right, calculate the
diss olved oxygen concentration of this solution in parts per million.
You r response should include both a correct numerical setup and

calculated result.

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