How do high temperatures affect liquid deicers? 

Most commercial liquid deicers are going to be formulated to be stable within the typical temperature ranges for their regular use. Are there ideal temperature ranges for liquid deicers? Is anything catastrophic going to happen if they are stored outside those temperature ranges?  Temperatures can affects common liquid deicers.   

High temperature range:  Usually, what we are most concerned with regarding high temperature storage is the possibility of chemical decomposition. Molecules are in constant motion; they are always vibrating, they are always shaking, and temperature is really a measurement of how fast those molecules are moving.  The higher the temperature of a substance, the faster those molecules are vibrating.  You can imagine that as we raise the temperature of a material, their molecules start shaking more and more.  At some point, they shake so hard that you can start breaking the molecule apart and atoms will start flying off all over the place. 

How sensitive a chemical is to temperature is going to depend on how strongly put together it is. Molecules that have very strong connections between the atoms will be stable.  On the other hand, we can have molecules that are relatively fragile, and if you start shaking them too much they will start breaking apart. It is going to vary from chemical to chemical. It turns out that the chemicals that we use for deicing are more or less stable to elevated temperatures. 

When you think of our deicing products, they are inorganic salts, like sodium chloride, magnesium chloride, and the acetates.  They are quite temperature stable. You could melt rock salt and it is not going to do anything. Magnesium chloride and calcium chloride, can start decomposing at a high enough temperature.  Magnesium chloride, for example, will start forming an insoluble compound called magnesium oxychloride, but that is not going to start happening until you get above 450 degrees Fahrenheit.  So that is not going to be an issue for any standard storage condition.  Acetates will also decompose if they get hot enough, but, again, potassium acetate does not decompose until you get above about 558 degrees Fahrenheit.   

Organic additives usually come in the form of organic compounds and they tend to be somewhat more temperature sensitive than the simple inorganic salts. The most common additives in organic deicing liquids are simple carbohydrates.  If you get them hot enough they will start to breakdown, but simple carbohydrates don’t start decomposing until you get above about 290 degrees Fahrenheit. There is the small possibility of indirect decomposition, say through microbiological growth or mold growth in organic liquids. There was probably more of an issue in the earlier generations of these products than in current products, so it is something you can ask the manufacturer about if you want to get more information.

If you look at the directions or the technical data sheets on liquid deicers, it will usually recommend that they be stored at cool temperatures, and that is always a good idea just to avoid or minimize the risk of any temperature-induced decomposition.  High temperature storage is not something we are especially worried about with liquid deicers.