Sep 17, 2023

The Science Behind Saltwater Freezing

The ocean is a strange and mysterious place. It also happens to freeze a little differently than the water in your kitchen sink.

When pure science behind saltwater freezing, its molecules organize into a crystal lattice that forms ice. But the salt (NaCl) dissolved in water interferes with this process and blocks the water molecules from getting close enough together to form ice. As a result, it takes much more energy for the water to freeze when there’s salt in it than when there isn’t.

This is why you see road crews spreading salt on icy roads; it helps the ice melt by lowering the temperature at which the water freezes. The higher the concentration of dissolved salt, the lower the freezing point.

The Science Behind Saltwater Freezing: Exploring the Briny Chill

The science behind saltwater freezing is fascinating to scientists because it gives them a better understanding of how Earth’s climate system functions. Changes in sea ice dynamics, for example, can ripple across the ocean and influence global weather patterns. The better we understand how this works, the more we can protect marine life and preserve delicate ecosystems.

To study the effect of salt on the freezing point, researchers used static, symmetric droplets of pure water and saltwater to measure the propagation velocities at which the liquids began to freeze. The results show that salt slows down the freezing rate by 140x compared to pure water. The researchers have also experimented with directional freezing (which is the relocation of impurities away from ice crystals) and found that it can significantly improve desalination efficiency.