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Topic: Why did saturated lime water form a crystaline film?  (Read 1467 times)

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Offline Ragnor

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Why did saturated lime water form a crystaline film?
« on: July 14, 2015, 09:53:49 PM »
 Hello, I recently made a bucket of lime water. It was my first time doing such. My intention being to use it to dilute and PH adjust cows milk for feeding a foal.
So I cleaned out a white, food grade plastic bucket. I filled it to a certain level and added about 1 cup of hydrated agricultural lime (Calcium Hydroxide). I stirred the mixture vigorously several times with a dry debarked maple stick. After several hours of intermittent observation the water became noticeably clearer and the undissolved lime began to stratify out of the solution. Just under the surface was a very fine foamy looking film that would resurface if stirred.

 So I left the pale of solution 24 hours and went back out to inspect the result. To my surprise there was a very thin, off white, crystalline, film across the entire top of the solution in the bucket. It made a very nice tinkling sound and broke when I pushed on it with my stirring stick. If I poked at the fragments they would now sink on edge to the bottom.
 The material seamed to be somewhere between a crystalline sheet and a flexible adhesive film. It will form to the stirring stick once wetted.

 Soooooo the big question on my mind. What is that stuff? I didn't read that as being part of the standard lime water saturation procedure. Can any of you experienced chemist types give me a likely scenario explaining the formation of this crystal film and what it is probable to be chemically?

 My lime water has a crystal film on top, why did it do that?

Offline PhotoElectroMaterials

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Re: Why did saturated lime water form a crystaline film?
« Reply #1 on: July 14, 2015, 10:44:17 PM »
It is possibly due to the CaCO3 (white and sparingly soluble in water) formed as a result of the reaction between calcium hydroxide and atmospheric CO2.  Calcium hydroxide is a well know CO2 scrubber.

Offline Ragnor

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Re: Why did saturated lime water form a crystaline film?
« Reply #2 on: July 15, 2015, 03:20:05 PM »
 Thank you for the reply, CaCO3 was my best guess but it's good to have the opinion of a more well versed chemist.
This also provides an interesting insight into the local geology. I used well water, from my well to fill the bucket. I occasionally find large masses of calcite crystals in the local region. This gives me some insight into they're formation as certain parts of the local geology are co2 rich basaltic emplacements. I will now suspect that the local clays are likely calcium rich.

 Thanks.

 I will leave off the Jesse Pinkman science meme image  ;D

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