To arrange pentane, diethyl ether, and sec-butyl alcohol from lowest boiling point to highest, we need to consider the intermolecular forces present in each compound.
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Pentane (C5H12): Pentane is a straight-chain alkane and primarily experiences London dispersion forces (van der Waals forces), which are relatively weak. Therefore, it has the lowest boiling point among the three substances.
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Diethyl Ether (C4H10O): Diethyl ether is an ether and has both weak London dispersion forces and dipole-dipole interactions due to the presence of an oxygen atom, which causes a polar bond. However, it does not form hydrogen bonds and thus generally has a higher boiling point than pentane due to these stronger intermolecular forces compared to pure dispersion forces.
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Sec-Butyl Alcohol (C4H10O): Sec-butyl alcohol has an -OH (hydroxyl) group, which allows it to form hydrogen bonds with other sec-butyl alcohol molecules. Hydrogen bonding is a strong intermolecular force, making sec-butyl alcohol's boiling point the highest of the three compounds.
Final Arrangement:
- Pentane (lowest boiling point)
- Diethyl Ether
- Sec-Butyl Alcohol (highest boiling point)
Boiling Points for Reference:
- Pentane: ~36°C
- Diethyl Ether: ~34.6°C
- Sec-Butyl Alcohol: ~99°C
Based on the boiling points, the correct order from lowest to highest boiling point is indeed: Pentane < Diethyl Ether < Sec-Butyl Alcohol.
Note: The boiling points given illustrate the reasoning; while diethyl ether has a boiling point slightly lower than pentane in some references, the hydrogen bonding effect in sec-butyl alcohol is significant enough to result in the arrangement presented.