How do solutions in water of molecular compounds and ionic compounds differ?
An aqueous solution of a molecular compound will not be electrolytic; an aqueous solution of an ionic compound will be electrolytic.
Ionic compounds are dissociated in water forming ions.
In molecular compounds, atoms are joined by covalent bonds, while in ionic compounds, they are joined by ionic bonds. Ionic compounds contain ions and are held together by the attractive forces among the oppositely charged ions. Molecular compounds contain discrete molecules, which are held together by sharing electrons (covalent bonding). http://www.britannica.com/eb/topic-388141/molecular-compound