Ask A Scientist General Science Archive

Question:  I am trying to find the freezing point of sea water.  
Can I get some help here?  It's my first time trying this feature.
 ken levine

Answer:
The freezing point of seawater depends upon it's salinity,
which is the amount of salt that it contains.  Open ocean seawater
has a salinity of about 35 (no units are used for salinity
anymore, although you may see it called o/oo which means
parts per thousand or psu, which means practical salinity units.
Neither usage is now considered correct). Anyway, fresh
water freezes at 0 degrees Celsius and 35 water freezes
at about -2 degrees C. The decrease is linear so that water
with a salinity of 17 freezes at about -1 degree C.
Stacie