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#### Samlearner120

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##### What substance would disappear in thin air?
« on: September 22, 2018, 11:26:23 AM »

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!
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#### wildfyr

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##### Re: What substance would disappear in thin air?
« Reply #1 on: September 22, 2018, 03:54:46 PM »

Dry ice? How long are we talking about here for something to disintegrate.
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#### Samlearner120

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##### Re: What substance would disappear in thin air?
« Reply #2 on: September 22, 2018, 10:41:27 PM »

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.
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#### Borek

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##### Re: What substance would disappear in thin air?
« Reply #3 on: September 23, 2018, 01:07:39 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, 04:50:12 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.
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#### Borek

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##### Re: What substance would disappear in thin air?
« Reply #5 on: September 23, 2018, 08:08:48 AM »

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, 01:38:50 PM »

A pile of iodine will do the same thing. Slowly go from solid to gas, but smell horrid and be rather dangerous.
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#### Enthalpy

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##### Re: What substance would disappear in thin air?
« Reply #7 on: September 24, 2018, 04:52:00 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. Logged #### Enthalpy • Chemist • Sr. Member • Mole Snacks: +240/-54 • Offline • Posts: 2802 ##### Re: What substance would disappear in thin air? « Reply #8 on: September 25, 2018, 11:42:38 AM » Camphor. It stinks. Contact and inhalation have adverse effects, but at least they are very well known. Logged #### P • Full Member • Mole Snacks: +63/-15 • Offline • Gender: • Posts: 629 • I am what I am ##### Re: What substance would disappear in thin air? « Reply #9 on: September 26, 2018, 12:26:02 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. Logged Tonight I’m going to party like it’s on sale for$19.99!

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#### Samlearner120

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##### Re: What substance would disappear in thin air?
« Reply #10 on: October 28, 2018, 07:04:22 PM »

wow Thank you so much guys! You all rock! Let me discuss these with my team.
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#### AWK

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##### Re: What substance would disappear in thin air?
« Reply #11 on: October 28, 2018, 11:59:01 PM »

NH4Cl will disappear slowly.
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