Solid table salt does not conduct electricity. How does dissolving salt in water allow electricity to flow?
When solid table salt (sodium chloride, NaCl) is not dissolved in water, it is in the form of a crystal lattice structure, with tightly held ions. These ions are not free to move and carry electric charge, so the solid salt is a non-conductor of electricity.
However, when salt is dissolved in water, the crystal lattice breaks apart, and the Na+ and Cl- ions separate and disperse throughout the water. In this dissolved state, the ions are free to move and carry electric charge. This is because water molecules, which have a polar nature (one end with a positive charge, and the other with a negative charge), surround the ions and create a hydrated shell. The water molecules effectively shield the charged ions and allow them to move more easily.
When a voltage is applied across the solution, the free moving Na+ and Cl- ions act as charge carriers and conduct electricity. The positive Na+ ions are attracted to the negative electrode (cathode), while the negative Cl- ions are attracted to the positive electrode (anode). This movement of ions in response to the applied voltage creates an electric current, allowing electricity to flow through the solution.
In summary, dissolving salt in water allows electricity to flow because it breaks the crystal lattice structure, freeing the ions to move and carry the electric charge, facilitated by the polar nature of water molecules.