Passage IV

Alcohols are carbon compounds that contain a hydroxyl (-OH) group bonded to a C atom. If the hydroxyl-bonded C atom is bonded to only one other C atom, or to no other C atoms, the alcohol is a primary alcohol. Table 1 lists the chemical formula, melting point, and boiling point for several primary alcohols.

Figure 1 shows how the viscosity (in centipoise, cp)of 3 primary alcohols varies with temperature.

Figure 2 shows how the viscosity of aqueous solutions of the same 3 alcohols varies with alcohol concentration at 20℃.

18. The primary alcohol 1-hexanol has the chemical formula CH3(CH2)5OH. Based on Table 1, the boiling point of 1-hexanol is most likely:

Answer and Explanation

Your Answer is

Correct Answer is H

Explanation

Look at table 1. As the molecular weight of alcohols increases, the boiling point becomes higher and higher, so the boiling point of 1-hexanol should be higher than that of 1-pentanol at 138 degrees. For each additional C atom, the boiling point increases by about 20 degrees (except for methanol-ethanol). So the boiling point of 1-hexanol should be around 138+20=158. The closest should be option H