Question

It takes a lot of energy to break covalent bonds, so both allotropes are hard to melt. Would you expect them to dissolve?

Answer 1

There are two most common allotropes of carbon - Diamond and graphite.
Diamond has a three dimensional structure of carbon atoms covalently bonded with each other.Due to this huge network of bonded carbon atoms, it has a high melting and boiling point. Therefore , diamond is hard to melt. In graphite also , there is a hexagonal structure and the carbon is bonded by covalent bond. Hence , graphite also has high melting point. But the melting point of graphite is less than of diamond. Both diamond and graphite are insoluble and does not dissolve in both water and other organic solvent. Both diamond and graphite has a strong covalent bonding such that there is a strong force of attraction between the carbon atoms that the solvent molecules cannot overcome that force.