How does salt affect the freezing process of water?

Answer 1

Salt molecules bond with water molecules, making it more difficult for ice to form. The result is a solution with a lower freezing temperature. For example, a 10% salt solution freezes at 20°F (-6°C), while a 20% salt solution freezes at 2°F (-16°C).

Answer 2

When you add a salt to water and the container feels cold, yes, an
endothermic reaction is taking place. The solution is grabbing heat from
the surroundings to get the salt to dissolve. When you add a salt to
a pure solvent (say, water), the freezing point will go down and the
boiling point will go up. That's because the vapor pressure of the pure
solvent is lowered (this would be easier to explain with a phase diagram).
Remember, the definition of BP is the temp at which the solution's vapor
pressure equals the external pressure. By lowering the vapor pressure,
the whole phase diagram shifts...BP to the right (higher), FP to the left
(lower). You may want to check out a intro level chemistry text or at
least draw out the phase diagram to see more clearly what gets lost is
just words here. Did you ever try boiling water without heating it?
If you have the means, hook up a vacuum to a flask of water. You don't
change the vapor pressure of the water, but you reduce the external
pressure enough so that the water does boil. Good question!

Answer 3

The salt will lower the freezing (and boiling) temperature. This is why people add salt to water before they boil it, to speed the process, and also why the ocean's water does not appear to be frozen (because it's not) even when it is less than 32*. Of course, currents play a role in that as well.

Answer 4

The sodium ions in salt water disrupt the crystallisation (freezing) of water. I think this happens because the positive sodium ions block the weak inter molecular bonds between the water molecules that would otherwise link the water molecules up into a crystalline structure (ice). As the temperature is lowered the sodium (and chloride) ions come out of solution to crystallize back into solid salt allowing more of the water to turn into ice.

Answer 5

It lowers the freezing point by physically getting in the way of the crystal formation. So the more ions are present the lower the freezing point. NaCl gives 2 ions, Na+ and Cl-, CaCl2 gives 3 ions Ca++ and 2 Cl- so road salt is calcium chloride because it gives more ions to lower the f. p.

Answer 6

Salt lowers the temperature at which water freezes and melts. Pure water,
H2O, freezes (and melts) at 0°C (32°F). But the more "salt" (any elements
or compounds carried by the water in solution, such as Na (sodium), Ca
(calcium), Cl (chloride), and SO4 (sulfate)) in water, the lower its
freezing point. For example, seawater, which has approximately 3500 parts
per million "salt" (including Na, Ca, Cl, SO4, Mg, K, and CO3), will freeze
(and melt) at -2.2°C. A water with extreme salinity such as very salty
lake waters at Death Valley, California (approximately 300,000 parts per
million "salt") may freeze and melt at temperatures as low as -20 - -30°C!
Because salt lowers the freezing point depression, it is added to icy roads
in order to melt the ice.

The reason why salt lowers the freezing temperature of water is a bit more
difficult to explain without discussing more complex chemistry. Basically,
pure water, H2O, is a different substance than salt water, such as NaCl-
H2O. As different substances, they have different chemical properties.
Salt "gets in the way" of the interactions between H and O, making it
harder for the H and O to bond as ice.

You can do very simple processes in the lab or classroom illustrating this
principle. Fill two containers with water and put table salt in only one
container of water. Put both containers somewhere cold (in the freezer or
even outside over night). See what happens!

Answer 7

It lowers the freezing point of water from 0 Celsius to -21.1 Celsius depending on the amount of salt. Salt warms the water molecules and prevents them from attaching to ice molecules.

Answer 8

salt lowers the freezing point of water a lot below the normal which is why some deicing fluids and liquids contain a lot of salt or sodium chloride

Answer 9

Im...im not positive, but if you dip salt in ice and put it on your skin it does a few tyhings...

it drains the water from your skin, makes the ice freeze at a faster colder temperature and bonds with your skin creating a burn. i dont know how it affects the freezing process...but it def...effects the process of un-freezing

Answer 10

It does lower the freezing temperature.