Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: Christa Lansdell on 11/02/2011 21:30:03

Title: Why does the crystal in my lamp leak fluid?
Post by: Christa Lansdell on 11/02/2011 21:30:03: Christa Lansdell asked the Naked Scientists:

Hi Chris,
Â
Please could you advise me.Â I have bought a rose quartz lamp for the Augrabies area Northern Cape.Â The one I have is a carved bowl with the lamp fitting in it and then you put a lot of smaller pieces of rose quart over the bulb and the light shines through.Â I have not been able to use the lamp as this quartz just weeps water or some clear fluid?Â If I move it away and take it all apart and leave it to dry out that works but if I put it back together again then the weeping starts again.
Â
Kind regards
Christa

What do you think?
Title: Why does the crystal in my lamp leak fluid?
Post by: JimBob on 12/02/2011 18:58:24: There are no fluids coming from the crystal's structure. The crystal's component atoms just will not move as this structure is very very stable. I would suspect that the heat from the lamp is causing condensation. To me this is the most likely source of the liquid.
Title: Why does the crystal in my lamp leak fluid?
Post by: Bored chemist on 13/02/2011 14:15:41: Are you sure it's real quartz?
Quartz is fairly stable (as are most rocks) and shouldn't do this.
Also a lamp may become warm, but it's cold things that attract condensation.
Title: Why does the crystal in my lamp leak fluid?
Post by: RD on 13/02/2011 17:04:02: Maybe a pet animal is the source of the liquid in the bowl ...

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Title: Why does the crystal in my lamp leak fluid?
Post by: JimBob on 14/02/2011 01:46:38: Quote from: JimBob on 12/02/2011 18:58:24
... I would suspect that the heat from the lamp is causing condensation. To me this is the most likely source of the liquid.

Quote from: Bored chemist on 13/02/2011 14:15:41
...
Also a lamp may become warm, but it's cold things that attract condensation.

OK, BC. Since I am not English by birth, what in an English winter would cause water to condense out out of the cold, damp English air?
Title: Why does the crystal in my lamp leak fluid?
Post by: Bored chemist on 14/02/2011 06:53:13: Well, as an example, my fridge does.
The point is that it does so by getting cold, not warm.
Title: Why does the crystal in my lamp leak fluid?
Post by: Geezer on 14/02/2011 08:03:08: Ah, well, see, obviously, this is on account of localized humidity effects. When the light is on, it raises the temperature of the air in that vicinity, which allows that air to contain a lot more water vapour than the surrounding air. But when the light is switched off, the water vapour in the air that was drawn into the mass of relatively cool crystals condenses on them

EDIT:

Actually, the lamp may be creating a convection current that draws humid air over the relatively cool crystals. If the air is humid enough, the water vapour in the air will condense on the cool crystals.
Title: Why does the crystal in my lamp leak fluid?
Post by: RD on 14/02/2011 09:07:53: OK if not pet pee, what about the lamp being made of hygroscopic (http://en.wikipedia.org/wiki/Hygroscopy) material,
adsorbing (http://en.wikipedia.org/wiki/Adsorption) water from the atmosphere: its peculiar surface being a sort of catalyst for condensation.

apparently quartz is adsorbant ...

Quote
Liquid water has positive adsorption on the surface of quartz;
the value of the specific adsorption decreases with increasing temperature
http://www.springerlink.com/content/p472622441022314/

If true the quartz lamp should "leak" even more* when not used, (when not heated by the lightbulb).

[* assuming constant humidity ]
Title: Why does the crystal in my lamp leak fluid?
Post by: Bored chemist on 14/02/2011 19:08:57: "which allows that air to contain a lot more water vapour than the surrounding air. "
Fine, but where might that water come from?

"If the air is humid enough, the water vapour in the air will condense on the cool crystals."
Yes, but if the crystals were cold enough to do that then they would be colder than the air round them. You could use that temperature difference to run a heat engine and you could solve the world's energy crisis.
Or, alternatively, you are wrong.

How could the crystals be that cold?

The same problem happens with the idea that the quartz absorbs water. Yes, it does (a bit) but, it does that because the quartz surface is a better place for the water to be than in the room so, when it sticks to the quartz, it stays stuck. It doesn't run off.
If it weren't stuck then I could put a waterwheel under it and...
Title: Why does the crystal in my lamp leak fluid?
Post by: Geezer on 14/02/2011 19:46:54: Quote from: Bored chemist on 14/02/2011 19:08:57
"which allows that air to contain a lot more water vapour than the surrounding air. "
Fine, but where might that water come from?

"If the air is humid enough, the water vapour in the air will condense on the cool crystals."
Yes, but if the crystals were cold enough to do that then they would be colder than the air round them. You could use that temperature difference to run a heat engine and you could solve the world's energy crisis.
Or, alternatively, you are wrong.

How could the crystals be that cold?

The same problem happens with the idea that the quartz absorbs water. Yes, it does (a bit) but, it does that because the quartz surface is a better place for the water to be than in the room so, when it sticks to the quartz, it stays stuck. It doesn't run off.
If it weren't stuck then I could put a waterwheel under it and...

So, are you coming down on the side of cat whizz then?
Title: Why does the crystal in my lamp leak fluid?
Post by: Bored chemist on 14/02/2011 22:10:38: Cat pee is a more plausible answer than some of the other ideas.
Title: Why does the crystal in my lamp leak fluid?
Post by: RD on 14/02/2011 22:19:31: Quote from: Bored chemist on 14/02/2011 19:08:57
The same problem happens with the idea that the quartz absorbs water. Yes, it does (a bit) but, it does that because the quartz surface is a better place for the water to be than in the room so, when it sticks to the quartz, it stays stuck. It doesn't run off.

Even when the solid surface is covered in a monolayer of water it can still be a preferential site for more water to be adsorbed ...

Quote
For physisorption, under appropriate conditions, gas phase molecules can form multilayer adsorption.
In chemisorption, molecules are adsorbed on the surface by valence bonds and only form monolayer adsorption.
http://en.wikipedia.org/wiki/Physisorption#Comparison_with_chemisorption
Title: Why does the crystal in my lamp leak fluid?
Post by: Geezer on 15/02/2011 01:13:19: Quote from: Bored chemist on 14/02/2011 22:10:38
Cat pee is a more plausible answer than some of the other ideas.

let us know when you are prepared to present your theory.
Title: Why does the crystal in my lamp leak fluid?
Post by: Bored chemist on 15/02/2011 06:57:11: Geezer, I did. You missed it.

RD, I do a fair bit of work on absorption and adsorption; I'm reasonably familiar with them. Neither of them help in this case.
If the quartz is where the water wants to be then that's where it will stay.
If it dripped off I could put a waterwheel under it and get free energy.
Title: Why does the crystal in my lamp leak fluid?
Post by: RD on 15/02/2011 18:08:40: Only other explanation I can think of ...

Quartz is piezoelectric â€¦ http://en.wikipedia.org/wiki/Quartz#Piezoelectricity
The (quartz) lamp is subject to stress from the heat of the light bulb: different parts are at widely different temperatures.
Mechanical stressing a piezoelectric material causes it to become electrically charged.
Charged objects attract particles in the air, like an old (CRT) TV screen collecting dust.

But do CRTs attract moisture [???]

If the lamp collects moisture when not used (not heated by lamp) this theory can be discounted.

[I prefer my previous hypothesis, no not the pet pee one]
Title: Why does the crystal in my lamp leak fluid?
Post by: Bored chemist on 15/02/2011 19:15:38: I prefer the hypothesis where we can get free energy and solve many of the world's problems.
I just don't believe it's correct. Things that violate the laws of thermodynamics tend not to be right.

A jolly good way of dissipating the sort of charge that you get from piezoelectric effects is to wet the materials.
Title: Why does the crystal in my lamp leak fluid?
Post by: yor_on on 18/02/2011 00:02:18: Do you live in a hot climate, containing much humidity? Your bulb will radiate some heat with the light and so create a higher temperature difference, possibly, as compared to the quartz creating a convection which may make water condense on the quartz. It should have to do with a temperature difference at least.

Are they containing the bulb like some 'globe' or are they hanging freely around it, by different threads? It would be easier to guess if you had a photo of it. Take a look at this one and see if it make sense for you Dewpoint. (http://www.temperatures.com/dewpoint.html)
Title: Why does the crystal in my lamp leak fluid?
Post by: JimBob on 18/02/2011 00:52:13: AH HA!!!

Thank you Yor_on - I knew there was something missing in this whole discussion as I have vacationed in Northern California on the coast. I was extremely damp, clammy to say the least, and water began forming on a lampshade when I turned on the lamp.

From the above cited web site --

"Conversely, if the temperature increases above the saturation temperature, dew will evaporate faster than it condenses."
Title: Why does the crystal in my lamp leak fluid?
Post by: Bored chemist on 18/02/2011 07:15:37: This is still the weird world where, if you want a vapour to turn into a liquid, you heat it.
Presumably, if you get the liquid cold enough it will boil.

I presume the OP wants an explanation that is plausible here on Earth and that doesn't violate the laws of physics.
Title: Why does the crystal in my lamp leak fluid?
Post by: Geezer on 18/02/2011 07:41:48: My car seems to attract a lot of water too. I'm thinking of hooking it up to a waterwheel to generate electricity.