Three isomeric compounds with the formula C H O exhibit the following solubilities in…
CHEMISTRY · Single correct · A Level · Chemistry · Bonding · Bonding
Problem
Three isomeric compounds with the formula C3H8O exhibit the following solubilities in water at 25 °C:
Compound Observed solubility
1-Propanol Miscible
2-Propanol Miscible
Diethyl ether (CH3CH2OCH2CH3) 8 g per 100 mL
Which statement best explains the trend in water solubility among these isomers?
(a) Branching in 2-propanol reduces its surface area, weakening London dispersion forces between its own molecules and allowing stronger attractions with water, so the branched alcohol (and 1-propanol as well) are completely miscible whereas the ether is not.
(b) Because diethyl ether is less dense than water, it cannot mix completely, whereas the densities of the alcohols are closer to that of water, so they are miscible.
(c) The two propanol isomers each possess an –OH group capable of both donating and accepting hydrogen bonds, whereas the ether can only accept hydrogen bonds, so its interactions with water are weaker and its solubility lower.
(d) The ether lacks an O–H bond, so its overall dipole moment is essentially zero; without a strong dipole it interacts only weakly with polar water, making it far less soluble than the alcohols.