Sciencemadness Discussion Board

freezing of sulfuric acid

rikkitikkitavi - 3-1-2003 at 15:09

http://www.resistoflex.com/sulfuric_graphs.htm#2

show some interesting graphs of physical properties of sulfuric acid.

When a 85 % solution freezes(45 F, about 4 C) , what is it that actually freezes? sulfuric acid I assume, but will it form a hydrate?

Will it mean that the remaining solution is weaker? (but can be reconcentrated fairly easy).

/rickard

rikkitikkitavi - 11-1-2003 at 07:51

first attempt with
150 gr 80% w/w sulfuric acid .Frozen at -30 C.

yielded two fractions, which both where temperated to 20C before concentration measurement where made.

1) 58 gr liquid , mass % measured to 78-80%

2) 92 gr sludge ,, concentration 80 % w/w.

The amount of high conc crystals separating doesnt seem to be enoug to increase the concentration in fraction 2).

I will try to find a way to filter the sludge, thus to increas solid % and see if this will help.

/rickard