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I'm working on a crafts project that is basically putting oil, water and glue in a bottle together with glitter just so you look at it. I want to see how it looks if the density of the oil is very close to that of the water-glue mixture.

The oil I'm using is baby oil, which sits on top of the water, so I need to increase its density. If I had wanted to increase the density of the water, I would just have added salt. Now I was thinking if there might another dense solute that I could dissolve in the oil to make the density do up, but I found that search engines interpreted my search terms in the wrong way and I couldn't find any.

That's why I'm here: to find a suitable solute. Originally I was thinking of powders, like the example of salt in water, but a dense liquid would also work. It would need to be something that's readily available commercially, and preferably not too expensive or dangerous.

Are there any dense solutes for oil that match my criteria?

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    $\begingroup$ Why can't you buy a denser oil? $\endgroup$
    – J. Ari
    Sep 22 at 17:07
  • $\begingroup$ @J.Ari densities are rarely listed on household products. I also probably wouldn't be able to get it as close to the density of the water (based mixture) as I want (which I might not be able to with a solute either, but at least I can try) $\endgroup$
    – Jasper
    Sep 22 at 17:41
  • $\begingroup$ You can try powdering any fat soluble vitamin from vitamin tablets (i.e. Vitamin E is a fat soluble vitamin) and see if that works. I think your safest approach is to do some research on oil products by finding the Safety Data Sheet (SDS) for the product online and noting the densities listed there. $\endgroup$
    – J. Ari
    Sep 24 at 14:18
  • $\begingroup$ And for even denser organic solvents, try bromoform. Iodine-substituted solvents tend to be somewhat unstable, though denser yet. $\endgroup$ Sep 26 at 23:32
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You can add drop by drop some heavy liquid like dichloromethane $\ce{CH2Cl2}$, which is heavier than water (density $1.336$). This substance will easily mix with any oil. Each drop added will increase a bit the density of the organic phase. When enough has been added, the mixture will have the same density as water.

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The @Maurice answer is OK-ish, but there is a better substance to mix with oil to get the desired density:

https://en.wikipedia.org/wiki/Tetrachloroethylene

(also called perchloroethylene and is also known by few other names)

  1. It is denser (~ 1.6) so less of it will be needed
  2. It is WAY less toxic than dichloromethane
  3. It is WAY less volatile than dichloromethane
  4. It is WAY less bad as an environment pollutant.
  5. It is cheaper.
  6. It is widely used as a dry cleaning agent, so it is commercially available and has more favorable regulatory status.

This substance is generally what you smell when you enter a dry cleaning shop. A cooperative dry cleaning worker may give or sell you the small amount you probably need (likely ~200g if I understand your idea).

p.s. be warned that organic substances expand/shrink more than water when their temperature changes. Your oily fraction will tend to float when hot and sink when cold. This is how lava lamps work.

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  • $\begingroup$ I found a place that sold 250mL of this for a reasonable price. I placed my order and will be back after I have tried it! $\endgroup$
    – Jasper
    Oct 6 at 11:25
  • $\begingroup$ Also, regarding the warning, that might actually be nice bonus. If for example the body heat from your hand could make it float, that would be absolutely awesome. $\endgroup$
    – Jasper
    Oct 6 at 11:27
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You can try powdering any fat soluble vitamins from vitamin tablets (i.e. Vitamin E is a fat soluble vitamin) and see if that works.

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  • $\begingroup$ won't do. First, these vitamin tablets are mostly inert material with small amount of the vitamin and second, none of these vitamins is denser than water. $\endgroup$
    – fraxinus
    Oct 4 at 7:51
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If the purpose is to increase the viscosity of your liquid (initially water) to let the glitter fall more slowly to the bottom of your test tube, then glycerol may be a non-toxic and affordable chemical to check here.

It is colorless (just as water), but considerably more viscous than water. If the viscosity is too high (compared to water), you may mix the two liquids in any ratio to obtain a clear solution of the two. Demixing (like oil and water) are thus unlikely.

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  • $\begingroup$ It's not, that's what I'm using the glue for (there's also some glycerol actually, but its main purpose is to keep the glitter from clumping). The idea is to create a part that doesn't mix (well) with the rest that's a different color. Thanks for your suggestion nonetheless! $\endgroup$
    – Jasper
    Oct 6 at 11:39

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