When it dissolves, water molecules congregate around the sodium and chloride ions and they separate. The water molecules orient themselves so that the partially positive hydrogens are directed toward the negatively charged chloride ions and the partially negatively charged oxygens are oriented towards the positive sodium ions. So each ion in solution has a "solvent sphere" of water molecules surrounding it in solution. The sum total of the interactions of all the solvent sphere water molecules makes up for the energy necessary to break the ions apart. When the ions break apart they become surrounded by water. Why is the freezing point lowered when salt is added to water?
When salt is added to water it dissolves into sodium and chloride ions. These ions bond with the hydrogen and hydroxide ions that water is made of, forming small amounts of hydrochloric acid causing some of the water to be removed from the overall system and becoming unavailable for the freezing process. Because there is less usable water, the rate of freezing and the freezing point decreases.
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