Freezing Behaviour of 36% Hydrochloric Acid

[awolokay]

Does anyone have any information on the freezing behaviour of 36% hydrochloric acid solution - specifically, does this solution expand on freezing, like water? It's one thing to land up with a pipe blocked by frozen solution - quite another thing to have a pipe rupture!

I've contacted various HCl vendors and Googled without any luck. Having not found anything, it is my suspicion that the solution does not expand, but I'd like something more than a guess.

The only other point of reference I have, is freezing of caustic soda solutions. With the much higher freezing point, this is something that happens far more frequently and yet I have not seen or heard of rupture problems in such lines.

One final option would be to carry out a test. If so, does anyone have any suggestions as to a lab that could do this? I haven't been able to find one.

Thanks

 

[micalbrch]

The density of fluids (apart from water) increaes with decreasing temperature as far as I remember. That means that the volume will not increase with falling temperatures. Check if you can get various densities of HCl at various temperatures to see if my assumption is right.

 

[awolokay]

Hi Micalbrch:

Yes, the density of MOST liquids does increase as the temperature decreases (i.e. the liquid shrinks). However, a particular exception is water where the density increases until 4 °C (39.2 °F if you're south of the line) and then it decreases again. The density of ice is less than the density of water at 4 °C - this is the reason icebergs float - ask the Titanic survivors about that!

The only other liquid that I know exhibits this behaviour is "type-metal" - the material used in the old days in printing presses. This behaviour was useful there to make sure that the nooks and crannies of the letters were completely filled.

So the question is, if you now dissolve HCl in water, which is what hydrochloric acid is, a solution of a gas in water, how much HCl has to dissolve in the water to change the expansion on freezing behaviour of the water, if indeed it is possible to change this behaviour?

 

[StoneCold]

awolokay
Here is a chart that says no, for 36% down to -5 C. Lower than that I am not sure.
How cold are you going?

http://www.solvaychemicals.com/Chem...rinated_inorganics/PCH-1300-0001-W-EN_WW_.pdf

 

[awolokay]

Hi StoneCold

Thanks for the try - but I live in the frozen north - we can get down to -40 °C and the freezing point of 36% HCl is about -30 °C (depending on which literature source you look at).