* Freezing Point Depression: When you dissolve salt (NaCl) in water, the salt ions (Na+ and Cl-) disrupt the formation of the regular, crystalline structure that pure water forms when it freezes. The water molecules need to be further apart to accommodate the salt ions, which requires a lower temperature to solidify.
* Colligative Property: Freezing point depression is a colligative property, meaning it depends on the number of solute particles in a solution, not the specific type of solute. So, any dissolved substance will lower the freezing point of water to some extent.
* Salinity: The more salt dissolved in the water, the lower the freezing point. Ocean water, with an average salinity of about 3.5%, freezes at about -1.9 degrees Celsius (-2.8 degrees Fahrenheit).
In summary: The presence of salt ions in water disrupts the formation of ice crystals, requiring a lower temperature for the solution to solidify.
