Potassium chloride is an ionic compound. The ions in potassium chloride are held together by strong electrostatic force of attraction. A lot of energy is needed to break down these bonds, hence the high melting point.
Category: Ionic Bonding
Explain why calcium oxide has a higher melting point than potassium fluoride.
The charges of Ca2+ ions and O2- ions in CaO is higher than that of K+ ions and F– ions in KF. The higher the ionic charge, the higher the electrostatic force of attraction between the oppositely charged ions, so more energy is required to overcome the electrostatic force in CaO than in KF.
Hence, CaO would have a higher melting point than KF.
Explain, using structure and bonding, why copper(II) nitrate cannot conduct electricity when solid, but can conduct electricity when molten or aqueous.
Copper (II) nitrate is an ionic compound. In the solid state, the ions of copper (II) nitrate are held in fixed positions in a giant ionic lattice structure. There are no mobile ions to conduct electricity.
In the molten or aqueous state, the giant ionic lattice structure is broken down. The ions are now able to move about. These mobile ions can act as charge carriers.