Search results
Results from the WOW.Com Content Network
The freezing point of seawater decreases as salt concentration increases. At typical salinity, it freezes at about −2 °C (28 °F). [ 1 ] The coldest seawater still in the liquid state ever recorded was found in 2010, in a stream under an Antarctic glacier : the measured temperature was −2.6 °C (27.3 °F).
At 20 °C (68 °F) one liter of water can dissolve about 357 grams of salt, a concentration of 26.3 percent by weight (% w/w). At 100 °C (212 °F) (the boiling temperature of pure water), the amount of salt that can be dissolved in one liter of water increases to about 391 grams, a concentration of 28.1% w/w.
However, the salt content of oceans lowers the freezing point by about 1.9 °C [41] (due to freezing-point depression of a solvent containing a solute) and lowers the temperature of the density maximum of water to the former freezing point at 0 °C.
The more salt added, the greater the effect on the freezing point. So, if it is 28 degrees Fahrenheit outside, adding extra salt might not be needed as much as if, say, it was 20 degrees out.
It is used because the addition of salt to water lowers the freezing temperature of the solution and the heat transport efficiency can be greatly enhanced for the comparatively low cost of the material. The lowest freezing point obtainable for NaCl brine is −21.1 °C (−6.0 °F) at the concentration of 23.3% NaCl by weight. [5]
The phenomenon of freezing-point depression has many practical uses. The radiator fluid in an automobile is a mixture of water and ethylene glycol. The freezing-point depression prevents radiators from freezing in winter. Road salting takes advantage of this effect to lower the freezing point of the ice it is placed on.
The water underneath becomes saltier and colder, leading to an increase in density. This parcel of water in the Okhotsk Sea is referred to as dense shelf water (DSW). The saltier and colder a water parcel is, the denser it becomes, causing it to sink below other parcels of water. For this reason, the DSW will begin to sink within the water column.
As seawater freezes in the polar ocean, salt brine concentrates are expelled from the sea ice, creating a downward flow of dense, extremely cold, saline water, with a lower freezing point than the surrounding water. When this plume comes into contact with the neighboring ocean water, its extremely low temperature causes ice to instantly form ...