What to do with a broken alum block

[BRITD]

~message from my Pharmacist/Chemist relative~
Likely picked up some impurities somewhere. From the air, metal pan or residual coating from the pan. Heating any crystal compound to its liquid boiling point [200 °C (392 °F) in this case], is not something I would try in my home. (noxious gas release, explosive. etc.).

 

[matt71]

Hydrolyzes to form sulfuric acid H2SO4.
Toxic and corrosive sulfur oxides form when heated to decomposition.

Sooooo, I'd say you probably overheated it and formed something nasty. Still puzzled by crystal color.

I agree with above, this is not a domestic process unless you have a fume/flame hood.

What to do with broken alum? Don't put in a double boiler and melt.
Looks like best way is to dissolve in a jar of water, 1 cup water/5 tablespoons alum.
Not quick.

 

[matt71]

http://chemistry.about.com/cs/howtos/ht/alumcrystal.htm

Can't hear at work, but looks like a better process. If you want a specific shape, that might be another challenge.

 

[VerbaVolant]

What to do with a broken alum block

I break them on purpose. Mix one tablespoon of alum powder with 180ml of distilled water and use it as deodorant in a spray bottle. That quantity lasts me around four to five months.

 

[yakster]

Larger broken chunks are great for the travel kit.

 

[tejolot3]

Larger broken chunks are great for the travel kit.

And the smaller bits are good for sprinkling on your enemies' breakfast.

 

[Heron]

http://chemistry.about.com/cs/howtos/ht/alumcrystal.htm

That looks like a fun project to do with my kids. Thanks, Matt! So, is the alum from the spices section of the grocery store the same stuff as an alum block?

 

[Roberto92]

I know this thread is dead. BUT!! The blue colour would be explained by copper sulfate deposits that would be bonded to the pan used to heat the salt. The copper pipes in the house would be leaching into the water used to cool the hot pan.

 

[Zhang Doe]

Very cool. The actual learning went over my head, but this is cool experiment. Thanks for documenting and sharing. Now let us know what happens when you light it on fire!