Based on cost, availability, and moisture absorption capacity, calcium chloride seems to be too good to be true. Are there any side effects to using calcium chloride as a desiccant?

I'm interested in effects that are directly attributed to the desiccant itself, not so interested in the effects of maintaining an extremely low moisture level in an enclosed environment.

For example, if I were to put a container of it in my vehicle, am I exposing the inside of the vehicle to corrosive fumes? Is there a danger of the calcium-chlorine bond breaking and releasing chlorine gas? I realize that the upholstery may dry up and crack if the moisture level is too low, but that can be managed. Rust build-up in the vehicle frame, not so much.

  • 2
    $\begingroup$ Is your goal with this to reduce the humidity inside your car or was that just an example of an enclosed space? I think you'll find that space isn't as enclosed as you might think, at least if the car is being used. $\endgroup$
    – airhuff
    Dec 22 '17 at 2:42
  • $\begingroup$ I agree. Even if it's not used, given how fast the interior cools down at the winter or autumn, the air exchange rate is probably high. The large amount of dessicant and forced airflow through it may turn out a major challenge. $\endgroup$
    – sa7
    Jan 4 '18 at 12:35

The only issue with $\ce{CaCl2}$ I've encountered is that eventually it pulls in so much water that it dissolves.

To keep dust down and to prevent the $\ce{CaCl2}$ solution from sloshing around, place it in a plastic container with a tightly-fitting sponge atop.

$\ce{CaCl2}$ is relatively non-toxic (it's used to make pickles), is inexpensive and is readily available, in cold climates, for melting snow and ice.


...if I were to put a container of it in my vehicle, am I exposing the inside of the vehicle to corrosive fumes?

Not so much fumes as dust particles from calcium chloride.

Inside the car the calcium chloride will get jostled about such that the granules will grind on each other and create dust particles. The dust particles will go everywhere. Calcium chloride will attract enough water so that it dissolves. Thus it would create a highly corrosive salt solution which could cause problems.

With all the modern electronics with connectors and PCB boards of all sorts the last thing I'd want in the car is something that could cause corrosion problems.


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