As Salinity increases, freezing point decreases?

Question

I do not understand the following:

Heat Capacity of water decreases with increasing salinity? How is that? Does that mean that water takes long to heat or get cold when there is more salt in sea water?

As salinity increases, freezing point decreases? Someone explain in simple terms please.

Thank you so much. Books just don't say it in simple terms.

Thank you all so much. I totally get it now. You guys are great and so smart as well.

Answer 1

The definition of heat capacity is: The amount of heat, or lack of, required to change the state of the substance.
Think of cold not as cold, but the lack of heat. Therefore it takes more cold (lack of heat) to freeze saline water. More cold (less heat) = Decreased heat of capacity.

Answer 2

Go to a Chemistry Book, they explain this much better than a geology book. Basically, depression of freezing point by solutes in a solution is what's called a "collagative" property. It depends on the number of particles in the solution rather than the specific compounds themselves. So more salt means more ions (the particles) which means a lower freezing point.

If you've ever made ice cream the "old fashion way", you will see an application. As the ice is salted, the cold water is still liquid at a temperature below freeezing, which make the ice cream firm.

Answer 3

As salinity increases freezing point definitely decreases. Salt water freezes at a lower temperature than fresh water.

Answer 4

Basically, your book is saying the more salt you add to water, the boiling temperature decreases.

It also says that as you add more salt, the temperature water needs to freeze goes down.