How does adding salt change seawater’s freezing point and boiling point?

Adding salt to water affects its physical properties through a phenomenon known as colligative properties, which depend on the number of dissolved particles rather than the nature of the particles themselves.1

• Freezing Point: Salt causes freezing point depression, meaning it lowers the temperature at which water turns into ice. By dissolving into ions, salt makes it more difficult for water molecules to bond together into a rigid, solid structure. Consequently, seawater requires a lower temperature to freeze than pure water.2
• Boiling Point: Salt causes boiling point elevation, which slightly raises the temperature at which water boils. While this effect is generally minimal, the presence of dissolved solutes increases the boiling point of the solution compared to that of pure water.3

These changes occur because the dissolved salt particles interfere with the phase transitions of the water molecules.23