Final answer:
When NaCl dissolves in water, the positive sodium ions are attracted to the oxygen end of water molecules while the negative chlorine ions are attracted to the hydrogen end, leading to the dissolution and stabilization of ions through hydration.
Step-by-step explanation:
When an ionic substance, such as NaCl, dissolves in water, ion-dipole interactions are responsible for the process. These interactions occur because water is a polar molecule, capable of surrounding and stabilizing ions in solution. The positive sodium ions (Na+) are attracted to the negative pole of the water molecule, which is the oxygen end. Conversely, the negative chlorine anions (Cl-) are attracted to the positive pole of the water molecule, which is the hydrogen end. This attraction allows water molecules to work their way into the crystal lattice of the salt, reducing the electrostatic attraction between the ions and ultimately leading to their dissolution into water.
Process of Dissociation
The process of ion-dipole attraction between the water molecules and the ions leads to dissociation, where the salt's ionic bonds are disrupted and individual ions are surrounded by water molecules. This stabilizes the ions in the solution and prevents them from rejoining into a solid form, which is why dissolution is considered a physical change.
Hydration of Ions
The sodium ions are surrounded by the oxygen end of water molecules, while the chlorine ions are surrounded by the hydrogen end. This surrounding of ions by water molecules is hydration, which is crucial in stabilizing ions in the solution after they have dissociated from the crystal lattice.