Ice Dam Help

[PRBuzz]

Originally Posted by ecduzitgood

I am confused, doesn't the solid calcium chloride generate heat untill it becomes liquid when exposed to water, either solid or liquid?

Stay confused, sometimes we are better off that way!


Point 1: yes when adding solid/dry CaCl2 to water it will get warmer. The more CaCl2 the warmer it gets. The mixing is "exothermic".

Point 2: CaCl2 in water will lower the freezing point of that water. Again, up until 30% (w/v) that freezing point depression will eventually reach -50C. (Question: anyone know how cold -50C is? DAMN COLD!)

When determining the freezing point (or eutectic point) of a given solution of CaCl2 in water it doesn't matter at what temperature the CaCl2/water solution starts from, it is not a measure of how many BTU's to cool only at what point does the solution freeze. So if I take room temperature water, add CaCl2 depending upon how much CaCl2 it may get detectably warm (to the hands or see movie above), then cool it down to freezing it will still have the same measured freezing point whether I start from room temperature water, warm/hot water, or even cold water. The graph attached earlier takes 20 or more different solutions of CaCl2 in water and measures the freezing point of each solution.


Side point: Car antifreeze, ethylene glycol, if you mix 2 parts anitfreeze with 1 part water you get a solution that freezes at ~70C. Don't mix ratios in any greater as the freezing point rapidly rises!