MCAT General Chemistry Question 266: Answer and Explanation

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Question: 266

3. Lyophilization would most likely be employed industrially in which of the following separations?

  • A. Salicylic acid dissolved in methanol
  • B. An enzyme in aqueous solution
  • C. NaCl in water
  • D. A small molecular drug dissolved in dichloromethane

Correct Answer: B

Explanation:

B Both dichloromethane and methanol are removed as liquids at reasonably low temperatures and have freezing points far lower than water. This eliminates choices A and D. The passage states that one of the major advantages to lyophilization is that it can be performed at low temperatures, and therefore preserve the activity of heat-sensitive samples. NaCl is a salt that is stable at high temperatures, whereas enzymes are proteins that denature at high temperatures. Therefore, lyophilization is best suited as a means to remove water from aqueous protein solutions.

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