Two structural isomers with the molecular formula ( C _2 H _6 O ) are added…
CHEMISTRY · Single correct · A Level · Chemistry · Bonding · Bonding
Problem
Two structural isomers with the molecular formula C2H6O are added separately to liquid water. Ethanol (CH3CH2OH) is completely miscible, whereas dimethyl ether (CH3OCH3) is only slightly soluble. Which statement best explains this difference in solubility?
(a) Ethanol has a lower molar mass than dimethyl ether, so the lighter molecules disperse more readily throughout the aqueous phase.
(b) Ethanol can both donate and accept hydrogen bonds with water because it contains an O–H bond, whereas dimethyl ether lacks an O–H bond and can only accept hydrogen bonds; the additional hydrogen-bond donation greatly increases ethanol’s solubility.
(c) Ethanol is much more polar than dimethyl ether because of its larger molecular dipole moment, and the greater polarity leads to greater solubility in the polar solvent water.
(d) Ethanol readily ionizes in water to form C2H5+ and OH− ions that are stabilized by the solvent, whereas dimethyl ether does not ionize, so it remains largely undissolved.