Safety of calcium chloride as a honey desiccant - any chemists out there?

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Arfermo 

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Going back to calcium chloride absorbing water (actually sufficient for it to be termed deliquescent), is that a chemical reaction? I think not in the chemical bonds sense. Initially it is simple hydration - probably only a matter of water of crystallisation and latterly dissolving in the water absorbed. The calcium chloride was solid and is now in solution. Not much of an overall chemical reaction there, methinks? Of course desiccation is carried out before the solution part. The Relative Humidity above a saturated calcium chloride solution is only 35% - so no desiccation at that point.

Have fun in arguing the toss.
This thread is bending my brains too early in the morning. Can we change the subject to beekeeping? Ort is that too mundane? :whistle: :whistle:
 

pargyle 

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This thread is bending my brains too early in the morning. Can we change the subject to beekeeping? Ort is that too mundane? :whistle: :whistle:
Oh ,,, I don't know - it's all vaguely connected with beekeeping and over 4 years it has wandered about a bit but interesting in places.
 

Bazzer 

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To save having a competition for who has the last word in this “debate”, it would be helpful for clarification of the terminology which is being used. I used the words “exothermic” and “endothermic” in the context of chemical reactions. I was quite specific in mentioning “chemical reactions”.

If you ask Dr Google for examples, you will find that the melting of an ice-block is described as an endothermic reaction. This is a physical event – the ice will melt if the ambient temperature is greater than the melting point of the ice. Yes, it is an endothermic reaction, caused by the ice absorbing heat from its surrounds, but it is a physical reaction, and not a chemical reaction. No chemical bonds are formed or broken in such a physical reaction. It is true that this can occur at ambient temperatures without generated heat being used, and you can rightly claim that the ice has absorbed heat from its surroundings.

BUT I was specifically talking about chemical reactions which involve chemical bonds being formed or reformed. The following information is from the website:
Simple Endothermic Reaction Examples

Chemical reactions are all about the energy. In an endothermic reaction, heat is used for the reaction to occur. The heat energy breaks the bonds in the substance causing the reaction. As the heat is absorbed, the product will be colder. This is actually one of the key characteristics of an endothermic reaction.

Dani, would you please advise an example of an endothermic chemical reaction which occurs at ambient temperatures in a laboratory?
Citric acid and baking soda react together endothermically at room temperature in solution - they can be used to make a chill compact. When talking about endothermic and exothermic processes it is important to define a system (e.g the chemical reaction mixture) and the surroundings. An endothermic process/reaction is one where energy needs to be transferred from the surroundings to the system to keep it at a constant temperature. With an exothermic process/reaction energy needs to be transferred from the system to the surroundings in order to keep the system at constant temperature. The actual constant temperature the system is being held at is irrelevant to the definition.
I lecture physical chemistry at University.
 

Bazzer 

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Going back to the OP - the method of drying with a dessicant in a sealed system is sound and calcium chloride can with care be used - however, safe disposal of the wet crystals is problematic.
I would suggest using molecular sieves instead - they are quite expensive but they are very safe and reuseable - you just need to put them in an oven to drive off the adsorbed water.
 

understanding_bees 

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Citric acid and baking soda react together endothermically at room temperature in solution - they can be used to make a chill compact. When talking about endothermic and exothermic processes it is important to define a system (e.g the chemical reaction mixture) and the surroundings. An endothermic process/reaction is one where energy needs to be transferred from the surroundings to the system to keep it at a constant temperature. With an exothermic process/reaction energy needs to be transferred from the system to the surroundings in order to keep the system at constant temperature. The actual constant temperature the system is being held at is irrelevant to the definition.
I lecture physical chemistry at University.
Thank you Bazzer, for your explanation which is very helpful. It appears that in my chemistry classes, all those years ago, that the "simple explanation" was given, rather than the more precise and fully detailed explanation.
 

understanding_bees 

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Well thanks for the warning
By the way, your definition of an endothermic reaction is wrong
A couple of detailed and helpful explanations have been given by other contributors, since you wrote the above comment. Your comment could have been much more helpful, and useful, if you had been more polite.
I can agree now that my understanding of the precise definition for an endothermic reaction was incomplete. Your comment, "your definition of an endothermic reaction is wrong" implied that I was totally incorrect.
 

coffindodger 

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Citric acid and baking soda react together endothermically at room temperature in solution - they can be used to make a chill compact. When talking about endothermic and exothermic processes it is important to define a system (e.g the chemical reaction mixture) and the surroundings. An endothermic process/reaction is one where energy needs to be transferred from the surroundings to the system to keep it at a constant temperature. With an exothermic process/reaction energy needs to be transferred from the system to the surroundings in order to keep the system at constant temperature. The actual constant temperature the system is being held at is irrelevant to the definition.
I lecture physical chemistry at University.
  • Penn & Teller's How to Play With Your Food
 

Amari 

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Going back to the OP - the method of drying with a dessicant in a sealed system is sound and calcium chloride can with care be used - however, safe disposal of the wet crystals is problematic.
I would suggest using molecular sieves instead - they are quite expensive but they are very safe and reuseable - you just need to put them in an oven to drive off the adsorbed water.
At last, three years on from the OP, I am convincingly reassured - thanks!
BTW, I'm usually left with a clear solution rather than 'wet crystals'. I pour it onto an area of gravel.
 

Erichalfbee 

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I use these in the motorhome and one of the bedrooms. The solution goes down the loo into the septic tank
 

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