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Topic: particles to be neutrally buoyant in liquid  (Read 7620 times)

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d4rr3n

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particles to be neutrally buoyant in liquid
« on: April 18, 2006, 08:46:42 PM »
I’m trying to find a harmless solution in which crystal particles which have a density of  3.62 - 3.67 g/ml will remain neutrally buoyant in the liquid as not to sink to the bottom or float to the top. The liquid must be clear or clearish at least so that the particles can easily be seen.
At first I was thinking of adding table salt to water to produce saline solution but I found out that you could not add enough salt to the water to produce the required density.
I reasoned that a denser substance other than table salt could be dissolved in the water to produce the same effect I am now looking for that substance.
 It must be non hazardous. I was wondering if you knew of a suitable substance. I am considering Potassium Chloride or Copper sulphate solution but not sure of the possibility since I’m not all that knowledgeable in chemistry.

I would be very grateful for any help on the matter.


Offline mike

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Re: particles to be neutrally buoyant in liquid
« Reply #1 on: April 18, 2006, 08:57:51 PM »
That is quite dense, I have no idea myself but I found this website maybe they can help:

http://www.heavyliquids.com/product_LST/lst.htm

By the way, copper sulphate is NOT a harmless solution.
« Last Edit: April 18, 2006, 08:59:53 PM by mike »
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d4rr3n

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Re: particles to be neutrally buoyant in liquid
« Reply #2 on: April 18, 2006, 09:15:38 PM »
I hope I got the density correct, the particles are strontium aluminate

Offline mike

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Re: particles to be neutrally buoyant in liquid
« Reply #3 on: April 18, 2006, 09:24:02 PM »
Maybe if you tell us a bit more about what you want to do. Presumably it is some sort of "glow-in-the-dark" contraption? Does it need to be in a solution or can you suspend it in a solid? or gel? latex?
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d4rr3n

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Re: particles to be neutrally buoyant in liquid
« Reply #4 on: April 19, 2006, 07:29:29 AM »
 I am trying to make glow in the dark liquid from Strontium Aluminate. So the problem is to try and find a liquid in which the particles will remain neutrally buoyant.
The problem is that strontium aluminate is quite dense so I need to find a liquid equally dense.
The other possibility would be to use something very viscous to significantly resist the sinking of the particles.
I have been thinking that if I could find a dense salt which can dissolve in water I could increase the density of the water until the particles float. It is not necessary that the solvent should be water, something denser then water but relatively safe would be ok. When I say relatively safe I guess what I mean is that I don’t want to use something that is very toxic or dangerous.
I tried mixing Strontium aluminate with Glycerine but the particles also sink after a while. I don’t know, maybe I could add something to the glycerine to increase its density but what? And what will dissolve in glycerine?

Offline mike

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Re: particles to be neutrally buoyant in liquid
« Reply #5 on: April 19, 2006, 08:30:14 AM »
I am not sure that you can suspend the particles indefinetly no matter what the density is. You could get close with something quite viscous although it sounds like you want it to pour(?) All the particles would eventually settle in a solution. Also if you simply make a supersaturated solution of a salt you will get crystals of that salt growing in the solution after a while. I think your best bet would be some sort of viscous oil, or even a transparent solid?
There is no science without fancy, and no art without facts.

d4rr3n

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Re: particles to be neutrally buoyant in liquid
« Reply #6 on: April 19, 2006, 02:31:27 PM »
Yes I need this liquid to pour so I don't want it too viscus. Glycerin is quite viscus and at the same time is denser then water so perhaps its a good starting point. Someone suggested that I dissolve salt in the glycerin to increase its density, is that possible? will salt dissolve in glycerin?

Offline mike

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Re: particles to be neutrally buoyant in liquid
« Reply #7 on: April 19, 2006, 08:56:23 PM »
I don't think that you will get "salt" to dissolve in glycerol. Salt = NaCl generally although it can refer to an infinite number of compounds.

Maybe you will have to try some sort of specially formulated polymer solution. You could try looking at paint/art supply shops, try finding out what the glow-in-the-dark industry uses, maybe try something similar to the medium used for things like fake stage blood or similar, as I am sure they are non-toxic and you could probably add your own pigment to the base.

If you used a polymer you could choose one that was designed to "cradle" the particles rather than simply rely on density.

Good luck, let me know how you go.

mike
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d4rr3n

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Re: particles to be neutrally buoyant in liquid
« Reply #8 on: April 20, 2006, 08:39:44 PM »
Another person I spoke to said:

Glycerin (Glycerol) has a density of 1.26 g/mL, so it is a bit denser than water.  Since it is a polar molecule (the OH group), it should, in theory, be able to dissolve polar and ionic solutes, just like water.  “Salt” being an ionic solute, should dissolve to some extent in glycerin

I guess the only way to find out if salt will dissolve in glycerol is to try it?

Offline mike

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Re: particles to be neutrally buoyant in liquid
« Reply #9 on: April 20, 2006, 08:45:47 PM »
Yes I think you are right, I think NaCl will dissolve in glycerol (sorry I was getting "salts" mixed up with the compound you are trying to suspend). And yes I guess you can try it and find out.

I just checked the CRC handbook and yes it does dissolve.
There is no science without fancy, and no art without facts.

d4rr3n

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Re: particles to be neutrally buoyant in liquid
« Reply #10 on: April 20, 2006, 09:14:39 PM »
How would I find out what the maximum quantity of salt I could add to the glycerin. I guess I could just keep on adding but there must be another way of finding out?

Offline mike

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Re: particles to be neutrally buoyant in liquid
« Reply #11 on: April 20, 2006, 09:33:31 PM »
I am sure someone would have done this before. However you could try it for yourself.

http://www.hbci.com/~wenonah/hydro/nacl.htm

This site says 1gram in 10mL of glycerine
There is no science without fancy, and no art without facts.

d4rr3n

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Re: particles to be neutrally buoyant in liquid
« Reply #12 on: April 20, 2006, 09:43:39 PM »
Thanks, according to that site salt dissolves better in glycerin then it does in water, I would never had thought that!

Offline mike

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Re: particles to be neutrally buoyant in liquid
« Reply #13 on: April 20, 2006, 10:08:06 PM »
I think it still actually dissolves better in water than glycerine :P

1gram in 2.8mL of water

cw

1gram in 10mL of glycerine
There is no science without fancy, and no art without facts.

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