Which statement about ionic compounds is correct regarding melting points and conductivity when dissolved or molten?

Which statement about ionic compounds is correct regarding melting points and conductivity when dissolved or molten?

• A. Low melting points but conduct electricity as solids.
• B. High melting points and they conduct electricity when dissolved or molten.
• C. Low melting points and do not conduct electricity.
• D. High melting points but do not conduct electricity.

Answer: (B)

Ionic compounds have high melting points because they’re held together by strong electrostatic forces in a crystal lattice. That lattice energy is large, so a lot of energy is needed to break it apart into a liquid. In the solid state, the ions are locked in place, so they can’t move to carry electrical charge, and the solid doesn’t conduct electricity. When melted or dissolved, the lattice breaks apart and the ions become free to move. These mobile ions provide charge carriers, allowing electricity to flow. So, they have high melting points and conduct electricity when dissolved or molten. For example, table salt (NaCl) doesn’t conduct as a solid, but conducts when melted or dissolved in water.

Ionic compounds have high melting points because they’re held together by strong electrostatic forces in a crystal lattice. That lattice energy is large, so a lot of energy is needed to break it apart into a liquid. In the solid state, the ions are locked in place, so they can’t move to carry electrical charge, and the solid doesn’t conduct electricity. When melted or dissolved, the lattice breaks apart and the ions become free to move. These mobile ions provide charge carriers, allowing electricity to flow. So, they have high melting points and conduct electricity when dissolved or molten. For example, table salt (NaCl) doesn’t conduct as a solid, but conducts when melted or dissolved in water.