MCAT General Chemistry Question 94: Answer and Explanation

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Question: 94

4. Which of the following processes has the most exothermic standard heat of combustion?

  • A. Combustion of ethane
  • B. Combustion of propane
  • C. Combustion of n-butane
  • D. Combustion of n-pentane

Correct Answer: D

Explanation:

Combustion often involves the reaction of a hydrocarbon with oxygen to produce carbon dioxide and water. Longer hydrocarbon chains yield greater amounts of combustion products and release more heat in the process—that is, the reaction is more exothermic. Of the hydrocarbons listed here, n-pentane is the longest chain.

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