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Do metals concentrate at the bottom of boiled water after being cooled off? (lemmy.world)
submitted 3 years ago by to c/askscience@lemmy.world
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[–] 7 points 3 years ago* (2 children)

If you have pieces of metal that you can filter out. Metals in water are usually in ionic form, they are "chelated" by water in solutions. Unless some salt is created and precipitate, solved metals distribuite over the solution to avoid concentration gradients.

So the answer is: what metal are you talking about? What is its form and concentration? Most likely, if you couldn't see depositions before boiling it, metal ions will likely stay in solution.

Boiling water is used to kill biological organisms. If you want to get "pure" water you need to distillate it or filter it with materials that can capture ions

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  • [–] [S] 2 points 3 years ago (1 child)

    what metal are you talking about? What is its form and concentration?

    Tap water, metal such as lead, copper, etc.

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  • [–] 5 points 3 years ago* (last edited 3 years ago) (1 child)

    They stay in the water when you boil it, what you need is a good filter. Most filters you find in the shop don't do much tbf, but I cannot suggest anything, I am not an expert on commercial products.

    If you distillate it you get rid of metals, but you also remove the so called minerals. Distilled water taste bad and is not really good for you

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  • [–] [S] 1 point 3 years ago (2 children)

    I boil my water, but I usually let it cool off and discard the last of it at the bottom, my understanding was that there was more concentration there.

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  • [–] 4 points 3 years ago

    I don't think that is how it works. You could buy an air still, but you really don't want to drink distilled water unless you add some minerals to it like calcium or fluoride. Water in nature always has dissolved minerals in it, and your body is designed with the assumption that those minerals are there.

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  • [–] 3 points 3 years ago* (1 child)

    Where did you read this? Unfortunately it doesn't work like that, unless you have concentration so high that a deposit is created. But, in that case, I wouldn't absolutely drink that water

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  • [–] 2 points 3 years ago (1 child)

    Having done some pilot scale experiments (60 l barrels), I’ve noticed that mixers are absolutely essential. At that scale, metals really do form notable concentration gradients.

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  • [–] 4 points 3 years ago* (last edited 3 years ago) (1 child)

    It depends on their form:

    1. solid metals are a separate phase, they create a deposit

    2. salts over a certain concentration, part create a deposit, so they slowly create a powder at the bottom, part stay in solution as ions

    3. Ionic metal in solutions spreads all over, as any concentration difference (gradient) generates an excess of free energy that the system naturally releases. You need to add external energy to maintain the gradient, such as a external electric potential gradient (an anode and a cathode)

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  • [–] 2 points 3 years ago

    Generally speaking, the experiments should follow the third category, but the system didn’t have enough time to reach equilibrium.

    If you have infinite time at your disposal, you can rely on diffusion to do its job. Unfortunately, the project had a finite amount of time allocated to it, and 60 l barrels are large enough that significant concentration gradients can exist. Found that out the hard way.

    LPT: Don’t start your experiments until all the mixers have arrived.

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    • [–] 7 points 3 years ago

    You don’t have to wait for it to cool. As water evaporates the dissolved solids in it reach a higher concentration. If the concentration becomes greater than the molecule’s solubility it will precipitate and fall to the bottom.

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