Can you dry out and reuse calcium chloride? - Motorhome Forums, Motorhome Discussion, Motorhome Chat

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post #1 of 21 (permalink) Old 19-01-2008, 14:04 Thread Starter
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Can you dry out and reuse calcium chloride?

We have one of those "holders" for calcuim chloride with the chemical in the top and a reservoir for the water collected underneath. The chemical stuff is damp and claggy, but no water is collected. Is it possible to dry out the stuff for reuse and thereby save a bit of cash. Or am I likely to blow myself up in the process? Stuck to biology at school - can you tell?

Sue

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post #2 of 21 (permalink) Old 19-01-2008, 14:20
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CaCl

Sue

You are taking me back to school now. Many of these kits state that the contents can be dried out. Put the contents in an old dish/tray and give a good stir. You need surface area rather than depth. The water will evapaorate.

CaCl + H2O = ...... erm I have forgotten that part.

Russell
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post #3 of 21 (permalink) Old 19-01-2008, 15:21
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You should not have a problem. Calcium Chloride is stable. It simply hydrates. I am not sure what temperature you need to dry it but it might not be economic. i.e. the cost of electricity exceeds the cost of new dry calcium chloride

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post #4 of 21 (permalink) Old 19-01-2008, 15:36
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Hi here is method, be careful of this stuff as it is caustic when liquid.

Calcium chloride (CaCl2) is probably the most common drying agent for general lab use. Besides low toxicity and low cost, its primary advantage is that it doesn't stop absorbing water when it reaches some fixed hydrate (e.g., 2H2O, 6H2O); it will keep going until it dissolves in its own water of hydration. Heat is of course generated during this process.
Sold under various trade names such as Damp-Rid, Humi-Dri, and Dry-Out, anhydrous CaCl2 must be kept in airtight containers to prevent it from liquefying as it absorbs atmospheric water. In other words, the compound has such an affinity for water that it will form a solution of itself from the water it pulls from the air.

Regenerating CaCl2: Even in a vacuum desiccator, calcium chloride will eventually become hydrated with use and will lose much of its drying power. The hydrated CaCl2 can be collected, put in a borosilicate glass beaker, and heated in an oven at or above 200C (392F) for a few hours. The hydrated CaCl2 will first melt, conforming to the shape of the container. The water will then begin to boil away (there will form puffed-up structures of dry CaCl2, which could overflow if a shallow container is used). When all the moisture has been driven off, the container should be covered immediately and allowed to cool. When cool enough not to melt plastic, it should be placed in a vacuum desiccator and the air evacuated. When fully cool it is then taken out of the desiccator and, if necessary, pulverized to 1/8-inch pieces in a sturdy mortar and pestle (do not grind it into powder; ideally it should be no finer than coarse sand). It must then be put into an airtight container as soon as possible.
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post #5 of 21 (permalink) Old 19-01-2008, 16:03
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Wow
After reading that I will buy a new pack. tho I haven't seen the large (1Kg+) plastic packs of it in the shops recently and the kits are sometimes cheaper than the refill packs

Never quite sure if it has much effect in the motorhome with all the vents anyway as we use the van regularly and its another item to pack away.

BTW Where should you dispose of the liquor? - we tip it down the sink with plenty of water.

Showing my age what's the calcium xxx?? we used to put in inkwells(!!) to produce acetylene gas when at school?

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post #6 of 21 (permalink) Old 19-01-2008, 16:06
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Not on any normal system of Chemistry!
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post #7 of 21 (permalink) Old 19-01-2008, 16:40
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Quote:
Originally Posted by homenaway
Showing my age what's the calcium xxx?? we used to put in inkwells(!!) to produce acetylene gas when at school?
Steve
Calcium carbide.

Tame stuff Steve. I dare not even mention the Ammonium salt we used to sprinkle on the floor (among other places) in the girls' loos at College.

Carolgavin will know, but she won't mention its name either!

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post #8 of 21 (permalink) Old 19-01-2008, 20:37 Thread Starter
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As Steve says "Wow"

Even more "Wow" as I think I can follow and understand you Carolgavin The container does not have any disolved stuff in the bottom yet so I will leave it a bit longer to see if it sort of disolves in its self.

(Now I know why I didn't do chemistry.)

Think I'm with you Steve - buy a new lot although meantime I will try your suggestion Russell if I can find a big flat container to put it in.

Many thanks to all of you for helping and responding so quickly. Who needs any other forum when we have this one?

Sue

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post #9 of 21 (permalink) Old 19-01-2008, 20:53
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Woolworths sell a small dehumidifier for 70, may be worth a look.

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post #10 of 21 (permalink) Old 19-01-2008, 21:06
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What was that tri-iodide stuff that we used to make in A-level chemistry that we sprinkled on the floor so that it would
c r e p i t a t e
when trodden on?
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