What temperature does salty water need to freeze?

Answer 1

The freezing point of salt water varies depending on how much salt is in the water. For example, water that is 3500 parts per million salt (avg. amount in seawater) will freeze around -2 degrees Celsius (28 degrees F). Water with an extreme amount of salt in it, like in some lake waters in Death Valley CA, with 300,000 ppm, will freeze at -20 to -30 degrees C (-4 to -20 degrees F).

The degree Fahrenheit (°F) is a unit of temperature named for the German physicist Gabriel Fahrenheit (1686 - 1736). In the Fahrenheit scale of temperature the freezing point of water is 32 degrees and the boiling point is 212 degrees, placing the boiling and melting points of water 180 degrees apart. Zero degrees Fahrenheit indicates the lowest temperature Fahrenheit could obtain by a mixture of ice and salt.
That depends on a number of factors including the concentration of salt in the water and the type of salt in the solution. Sodium Chloride (NaCl) can exist in aqueous (water-based) solutions with concentrations ranging from 0% to about 23% by weight. The maximum concentration, which corresponds to the saturation point for the solution, is dependent on temperature. The freezing point for a 23% NaCl solution is about -21 degrees C.

The salt that highway authorities apply to roadways depends on the expected minimum temperature. For roadway temperatures below -12 degrees C, authorities do not use Sodium Chloride but may use Calcium Chloride instead because it remains effective at lower temperatures.

The freezing temperature of seawater also depends on salinity (salt concentration) as well as pressure.

Answer 2

depends on the salt molal concentration and the salt
ΔTf = Kf · mB


so for a of 1.0 molal NaCl solution




ΔTf = Kf · mB
ΔTf = 2 · 1.0
ΔTf = - 2.0 degrees Celsius
This depends on how much salt is dissolved in the water. The more salt that is dissolved, the colder the freezing point.

Answer 3

The freezing point of table salt water is lower than the freezing point of pure water. This is because table salt (and other non-volatile solutes) cause freezing point depression. However, the exact freezing point of the solution depends on the concentration of salt. A higher concentration causes more freezing point depression than a lower concentration.

Answer 4

It depends on the concentration of salt. A small amount of salt lowers the freezing point by only a little bit. More salt means a lower freezing point. But, lower temperature means that less salt can be dissolved. These two trends taken together mean there is a minimum possible melting point. It is -21.10C at 23.3% salt by weight. This concentration is called the eutectic mixture. The eutectic for any mixture is the composition giving the lowest melting point.

There is a far more detailed discussion and phase diagram here:

http://webserver.dmt.upm.es/~isidoro/bk3/c07sol/Solution%20properties.htm

Answer 5

The freezing point depends on the concentration of salt; for sea water the freezing point is between -2 0C and -3 0C.

Answer 6

Generally -2 degrees Celsius (but the temperature depends on the concentration of salt in water).

Answer 7

The freezing point of salt water can vary by its salinity. The average freezing point of saltwater at normal levels is 28 degrees Fahrenheit.

Answer 8

Depends on the concentration of salt in the water, and a few other factors like air pressure. However generally speaking fully saturated water freezes at minus 5 Celsius.

Answer 9

Minus six degrees Fahrenheit