Posted: Jun 19, 2013 12:47 pm
When common salt dissolves in water, the salt molecules actually break apart into sodium and chlorine atoms, which get mobbed by clumps of water molecules. If I have it right, the oxygen ends of the water molecules stick to the sodium atoms, and the hydrogen ends of the water molecules stick to the chlorine atoms. What you end up with is neutral charged clumps of water molecules around equal numbers of sodium and chlorine atoms.
The atomic mass of chlorine is about a third heavier than sodium.
So, what prevents us from dissolving the salt, centrifuging the solution until the chlorine/water clumps are on the bottom of the solution and the sodium/water clumps are on the top. Decant off the top half of the solution, let the water evaporate, and collect your sodium.
I asked a team at Vespr, after watching Tyler DeWitt's presentation on What Happens when Stuff Dissolves?, this same question:
The team replied:
Why do you suppose it would take such insane centrifugation? It seems to me that if the sodium and chlorine water molecule clumps are indeed neutrally charged, the only real difference they would have then is their weight.
What's up with my idea?
The atomic mass of chlorine is about a third heavier than sodium.
So, what prevents us from dissolving the salt, centrifuging the solution until the chlorine/water clumps are on the bottom of the solution and the sodium/water clumps are on the top. Decant off the top half of the solution, let the water evaporate, and collect your sodium.
I asked a team at Vespr, after watching Tyler DeWitt's presentation on What Happens when Stuff Dissolves?, this same question:
I wrote:Superb work, Tyler. A quick question on ionic aqueous solutions... Would I be able to separate sodium from chlorine by centrifuging saltwater?
The team replied:
What a great question! So theoretically, yes. Centrifugation can be used to separate things of different masses. In saltwater, the Sodium and Chloride ions weigh about 2 to 3 times more than the water molecules. Unfortunately, however, the masses that we're dealing with are SO TINY that you'd have to spin a bottle of water at an incredibly fast speed in order to separate them out. Like, I'm just totally making this up here, but I'm guessing that it's about a million times faster than anything has ever been spun in the world. So could you actually do it? Maybe. But there would be an insane amount of energy required to power your centrifuges, and you'd be better off using other methods, like plain old distillation.
Why do you suppose it would take such insane centrifugation? It seems to me that if the sodium and chlorine water molecule clumps are indeed neutrally charged, the only real difference they would have then is their weight.
What's up with my idea?