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### Topic: What substance would disappear in thin air?  (Read 3054 times)

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#### Samlearner120

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##### What substance would disappear in thin air?
« on: September 22, 2018, 05:26:23 PM »
What chemical compound would slowly decompose/dissolve over time in normal conditions? I am trying to create a small statue that will decompose/disappear over time when kept in a normal room. If anyone can help me out, i'd really appreciate it.

Thanks guys!

#### wildfyr

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##### Re: What substance would disappear in thin air?
« Reply #1 on: September 22, 2018, 09:54:46 PM »
Dry ice? How long are we talking about here for something to disintegrate.

#### Samlearner120

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##### Re: What substance would disappear in thin air?
« Reply #2 on: September 23, 2018, 04:41:27 AM »
Thanks for replying! Ideally, we want the statue to last a year before it completely disintegrates. Even longer than that could work. Someone in the other forum suggested lead chloride but i am not sure about that one.

#### Borek

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##### Re: What substance would disappear in thin air?
« Reply #3 on: September 23, 2018, 07:07:39 AM »
Someone in the other forum suggested lead chloride but i am not sure about that one.

No way this is going to disappear.

However, you may want to elaborate on what you mean by "disintegrate". Imagine putting a sculpture made of just a kitchen salt in water. It will slowly dissolve and after some time you will be left with just a shapeless lump of the original material. Will such behavior be OK? Or do you hope for something that will keep the recognizable shape for as long as possible?
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#### Samlearner120

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##### Re: What substance would disappear in thin air?
« Reply #4 on: September 23, 2018, 10:50:12 AM »
By disintegrating, i mean 80-100% of it disappears gradually over a period of around a year.
In the example you gave, it works except the water. We were looking for something that would gradually disintegrate on reacting with the air.
It can be a shapeless lump or maintain the original shape, thats not an issue.

#### Borek

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##### Re: What substance would disappear in thin air?
« Reply #5 on: September 23, 2018, 02:08:48 PM »
And how safe does it have to be? I mean - the most logical approach is to use something volatile, but that will mean emitting minute amounts of gas. Will it be used in a well ventilated place, where the odor doesn't matter, or in a closed room, where the smell will be not acceptable? Some substances can be harmful when left inside, but it wouldn't be a concern in the open. For example, if you were able to find a way of forming ammonium carbonate (which is a white powder) with addition of some small amount of a binder (no idea if doable or practical) you could in theory get something that will slowly sublime, but it will probably stink of ammonia.

Not that I have any ideas or suggestions, but clarifying these details may help others come with some propositions.
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#### wildfyr

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##### Re: What substance would disappear in thin air?
« Reply #6 on: September 23, 2018, 07:38:50 PM »
A pile of iodine will do the same thing. Slowly go from solid to gas, but smell horrid and be rather dangerous.

#### Enthalpy

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##### Re: What substance would disappear in thin air?
« Reply #7 on: September 24, 2018, 10:52:00 AM »
Naphthalene too sublimes slowly. Unfortunately, it 's a bit carcinogenic.

Carane maybe? It's a solid and it must be about as volatile as carene
https://en.wikipedia.org/wiki/3-Carene
Camphene is a volatile solid
https://en.wikipedia.org/wiki/Camphene
all these smell strongly.

Cubane is still expensive. Adamantane is said to cost 1$/g https://en.wikipedia.org/wiki/Adamantane How fast does hexamethylene tetramine sublime? In a closed package in a cool location it lasts for years, but at heat this may accelerate. https://en.wikipedia.org/wiki/Hexamethylenetetramine You can adjust the sublimation rate by the temperature (including direct light) and by the wall thickness of the item. If a small item evaporates in a year, I don't expect the vapour concentration to be flammable, but the solid itself may be flammable. Besides sublimation, a solid's molecules could be broken by UV light and the fragments be volatile or reactive to air, but I have no suggestion for that. #### Enthalpy • Chemist • Sr. Member • Posts: 2914 • Mole Snacks: +254/-55 ##### Re: What substance would disappear in thin air? « Reply #8 on: September 25, 2018, 05:42:38 PM » Camphor. It stinks. Contact and inhalation have adverse effects, but at least they are very well known. #### P • Full Member • Posts: 639 • Mole Snacks: +64/-15 • Gender: • I am what I am ##### Re: What substance would disappear in thin air? « Reply #9 on: September 26, 2018, 06:26:02 AM » Ga metal? Turn the heating up when you want it to melt. This would work in a 'normal' room as you described - ice (or even better, dry ice) would probably melt too quickly. What about these new bio plastics made of algae that decompose? They go from being a bottle to being a pile of sludge in about a year I think. Tonight I’m going to party like it’s on sale for$19.99!

- Apu Nahasapeemapetilon

#### Samlearner120

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##### Re: What substance would disappear in thin air?
« Reply #10 on: October 29, 2018, 01:04:22 AM »
wow Thank you so much guys! You all rock! Let me discuss these with my team.

#### AWK

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##### Re: What substance would disappear in thin air?
« Reply #11 on: October 29, 2018, 05:59:01 AM »
NH4Cl will disappear slowly.
AWK