[neilep (OP)]

This should be an easy one..

..but I don't know the answers..do you ?

[eric l]

This should be an easy one..

..but I don't know the answers..do you ?

It is not an easy one for a number of reasons :
- sea water does not have the same salt content everywhere, for example :  the Mediterranean contains more salt (per liter) than the Atlantic; the English channel contains slightly less (because of the rivers that empty into it)
- as for freezing :  seawater is in constant movement, so even if you could determine the freezing point of a given sea water in lab conditions, this see will not freeze up at that temperature (you will have undercooling, probably about 4Centigrade).  So you would see icicles on every object around, while the sea water will still be liquid.
- the change in freezing point or boiling point depends on the concentration.  30 g/l of NaCl in water would account for a decrease in freezing point of about 18.5 °C and an increase in boiling point of about 5°C.
As an average, seawater contains about 35 g of salt per liter, not all of it is NaCl.  This would account for a lowering of the freezing point by about 20°C.  The Mediterranean contains about 40 g of salt per liter -) which would decrease the freezing point by about 24°C, the Baltic contains only about 25 g of salt per liter, which would account for a decrease in freezing point of about 15°C. 

[neilep (OP)]

THANK YOU ERIC.

Respects the Eric.

So, though I have asked what I thought was an easy question..has somehow transfered to my mastering the asking of not easy questions !

I actually did consider the difference in  ' saline joy ' amongst the seas and oceans but was hoping that your good self would sort it out for me.

What about the Dead Sea ?..now that is well salty...

Me has floated in it a few times !

THANK YOU again Eric...your answers are very helpful and insightful.

[eric l]

About the Dead Sea, from what I remember the concentration is quite close to saturated salt water.  And I used to prepare saturated salt water by mixing 1 kg of food grade salt and 2 l of water, which after half an hour stirring would leave me with a small deposit of undissolved salt after letting the mix stand overnight.  Density of such a mix was about 1.3 so, in weight over volume, the salt concentration would be about 390 g/l for saturated salt water (I do not have the exact data around, I can just give it from memory). 
I used to prepare saturated salt water and standard sea water while working on a project concerning oil well drilling fluids.  Sea water muds were used in off shore drilling, saturated salt water muds were used when they had to drill through salt layers.  

[neilep (OP)]

ERIC..THANK YOU.

I am really grateful for your kind answer.

Are you/were you some kind of petro-chemical engineer. ?..seems fascinating what you once did. Well, to an outsider like myself it does...I doubt you'll say it was a glamorous occupation. !

[eric l]

Actually I was a researcher, mainly on binders (natural binders for one employer, syntetic binders for another).  But some binders are used in drilling muds as well.  So I got involved in pretty much everything :  from paper and board to paints and coatings, building materials, anything non-food.  I did get involved in food project as a sideline, because of my experience with rheology.

[neilep (OP)]

Actually I was a researcher, mainly on binders (natural binders for one employer, syntetic binders for another).  But some binders are used in drilling muds as well.  So I got involved in pretty much everything :  from paper and board to paints and coatings, building materials, anything non-food.  I did get involved in food project as a sideline, because of my experience with rheology.

...and now you teach yes ? ( I did get that right didn't I ?..I am sure I saw you say once you're a teacher/lecturer !!)

I remember seeing a program about the science of drilling muds...amazing !!

[Monox D. I-Fly]

- as for freezing :  seawater is in constant movement, so even if you could determine the freezing point of a given sea water in lab conditions, this see will not freeze up at that temperature (you will have undercooling, probably about 4Centigrade).  So you would see icicles on every object around, while the sea water will still be liquid.

Aren't waterfalls able to freeze up? If waterfalls can do so, why can't sea?

[Colin2B]

- as for freezing :  seawater is in constant movement, so even if you could determine the freezing point of a given sea water in lab conditions, this see will not freeze up at that temperature (you will have undercooling, probably about 4Centigrade).  So you would see icicles on every object around, while the sea water will still be liquid.

Aren't waterfalls able to freeze up? If waterfalls can do so, why can't sea?

He’s not saying it cannot freeze, just that constant motion reduces the ability to freeze at the static (lab) temperature.