GRE Subject Test: Chemistry : Terpene Chemistry

Study concepts, example questions & explanations for GRE Subject Test: Chemistry

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Example Questions

Example Question #101 : Macromolecules

Which of the following molecule is a type of terpene?

Possible Answers:

\(\displaystyle C_3_5H_5_6\) because it is derived from an isoprene

\(\displaystyle C_3_5H_5_6\) because it is derived from a pentene

\(\displaystyle C_3_5H_7_0\) because it is derived from an isoprene

\(\displaystyle C_3_5H_7_0\) because it is derived from a pentene

Correct answer:

\(\displaystyle C_3_5H_5_6\) because it is derived from an isoprene

Explanation:

Terpenes are special classes of lipids that are derived from isoprene units. An isoprene unit’s molecular formula is \(\displaystyle C_5H_8\); therefore, terpenes must contain a molecular formula that is derived from a \(\displaystyle C_5H_8\) empirical formula.

The molecular formula \(\displaystyle C_3_5H_5_6\) consists of seven isoprene units (\(\displaystyle C_5_ \times _7H_8_ \times _7\) = \(\displaystyle C_3_5H_5_6\)); therefore, \(\displaystyle C_3_5H_5_6\) is a type of terpene.

Pentene is an alkene with the molecular formula \(\displaystyle C_5H_1_0\). \(\displaystyle C_3_5H_7_0\) (\(\displaystyle C_5_ \times _7H_1_0_ \times _7\)) is derived from pentene units; however, terpenes do not have pentene units.

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