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Ch.13 - Solutions & Their Properties
Chapter 13, Problem 53

Pentyl alcohol, CH3CH2CH2CH2CH2OH, is miscible with octane, C8H18, but methyl alcohol, CH3OH, is insoluble in octane. Explain.

Verified step by step guidance
1
Step 1: Understand the concept of miscibility and solubility. Miscibility refers to the ability of two liquids to mix in all proportions, forming a homogeneous solution. Solubility is the ability of a substance to dissolve in a solvent.
Step 2: Consider the molecular structure of pentyl alcohol (CH3CH2CH2CH2CH2OH) and octane (C8H18). Both have long hydrocarbon chains, which are nonpolar, allowing them to interact through London dispersion forces.
Step 3: Analyze the structure of methyl alcohol (CH3OH). It has a much shorter hydrocarbon chain and a prominent hydroxyl group, making it more polar compared to pentyl alcohol.
Step 4: Apply the 'like dissolves like' principle. Nonpolar substances tend to dissolve well in nonpolar solvents. Pentyl alcohol, with its long nonpolar chain, is more similar to octane than methyl alcohol, which is more polar.
Step 5: Conclude that the miscibility of pentyl alcohol with octane is due to their similar nonpolar characteristics, while the polarity of methyl alcohol makes it insoluble in the nonpolar octane.