Why does magnesium fluoride conducts electricity when molten or in aqueous solution?
The correct Answer and Explanation is:
Magnesium fluoride (MgF₂) conducts electricity when molten or in aqueous solution because it dissociates into ions, allowing the movement of charged particles. In its solid state, MgF₂ exists as a crystal lattice where magnesium ions (Mg²⁺) and fluoride ions (F⁻) are held together by strong ionic bonds, preventing the free movement of these ions. However, when MgF₂ is molten or dissolved in water, these ions are freed from the rigid lattice structure and are able to move, which is essential for conducting electricity.
In Molten State
When magnesium fluoride is heated to its melting point, the heat energy overcomes the ionic bonds in the lattice. This results in the breakdown of the solid structure into individual Mg²⁺ and F⁻ ions. Since these ions are now free to move within the liquid, they can carry an electric charge, facilitating the flow of current. The positive Mg²⁺ ions move towards the negative electrode (cathode), while the negative F⁻ ions move towards the positive electrode (anode), allowing electric conductivity.
In Aqueous Solution
Similarly, when MgF₂ is dissolved in water, it undergoes a process called dissociation, where water molecules surround and separate the Mg²⁺ and F⁻ ions from each other. The polar nature of water helps break the ionic bonds between Mg²⁺ and F⁻ ions, allowing them to disperse throughout the solution. These free-moving ions now act as charge carriers in the aqueous medium, enabling the solution to conduct electricity. The extent of ion dissociation is crucial for determining how well the solution conducts electricity.
In both cases, the presence of free-moving ions is the key reason magnesium fluoride conducts electricity when molten or in aqueous solution, as electrical conduction in ionic compounds depends on the availability of mobile ions.