The investigation begins
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A check on the internet reveals that the worlds oceans have a concentration of salt in water of around 35g/L. This can vary if the seawater is near a source of freshwater such as a river mouth, or in an area where there are high rates of evaporation such as the Dead Sea.
Making seawater
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It was simply a matter of measuring out 70grams of table salt into 2000mls of tap water and voila my synthetic seawater was ready.
In case anyone was wondering it tastes salty
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YARH it tastes of the sea....
"blath..pth ph pth"
My Method
I then took about 100mls of my synthetic seawater and poured it into a glass to set aside as a control. The rest I poured into a blue plastic container which I put into our freezer set at -9 degrees Celsius. I inspected the synthetic seawater and noted when it was beginning to freeze. This seemed to take longer than drinking water normally takes to freeze in our freezer. As the seawater froze, I collected it and added it to another glass and returned the remaining synthetic seawater to the freezer. I did this again and again until all I was left with was around 200mls of slushy liquid that didn't even freeze after being in the fridge over night.
Harvesting the ice
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"mmm not my kinda slushie"
The next day
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The next day the ice I had collected had melted and I now had three containers of liquid.
- My original synthetic seawater
- The melted ice I collected
- The slushie liquid that wouldn't melt
The taste test
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The slushie salt water tasted waaaaay saltier than my original synthetic seawater, but the ice that I collected tasted just like tap water. This is why the ice in Antarctica can be melted to provide fresh drinking water.
But if from our original 2000 millilitres we took out 100mls that's 7grams of salt leaving 63grams of salt in the 200mls of slush since none went into the ice. That's 315grams of salt per litre or 9 times saltier.
But if from our original 2000 millilitres we took out 100mls that's 7grams of salt leaving 63grams of salt in the 200mls of slush since none went into the ice. That's 315grams of salt per litre or 9 times saltier.
Of course, the seas around Antarctica aren't 9 times saltier because they can mix with the rest of the ocean, but it does mean they will be a bit saltier in the area where the ice is forming.