chemical clumping

[Dan Henderson]

I'm just beginning to mix some of my own chemicals. I bought some potassium bromide from the Formulary to mix with potassium ferricyanide for bleaching. The pot bromide is clumped together in rather large pieces. I believe it was this way when I recieved it. Is there any way of "unclumping" it and keeping it from "reclumping?" (And if someone wants to give me the chemically correct term for this condition, that would be okay too!)

 

[Photo Engineer]

I break it up with a heavy stainless steel spatula.

If you use a mortar and pestle, use a mortar with a rough ceramic glazed interior and rough glazed pestle to prevent contamination.

PE

 

[jim appleyard]

You can also be really cheap and use the butt end of a screwdriver. Just make sure you rinse the screwdrive off well.

 

[pnance]

I believe they invented the word clumping to describe the way potassium bromide adheres to itself.

 

[dancqu]

Is there any way of "unclumping" it and keeping
it from "reclumping?" And if someone wants to give
me the chemically correct term for this condition,
that would be okay too!

The term is deliquescence. More a matter of physics
than chemistry. I've had the same problem with potassium
bromide. Soft clumps. I weighed the Boston Round Glass Amber
bottle with the KBr before and after heating. My Acculab 0.01
gram scale found no difference in weight.

I think it quite likely that a 10% solution kept in glass will have
a many years life span; full or not. Boston Rounds are and have
been for ages a standard for chemical storage. They are not
expensive. Wide mouth and narrow. Be sure you have the
Polyseal or Polycone caps. Above one ounce size they
are fractions of a liter. Dan

 

[Photo Engineer]

Dan;

Sorry but deliquescence means "to become LIQUID from the absorption of water from air".

Clumping is the correct term in this case.

Hypo will become a liquid in hot humid air. I know, I shoveled many pounds of hypo slush around in the tropics. It is a real mess. Potassium bromide forming lumps is "clumping".

The definition was taken from my 2 volume home dictionary, but is confirmed by my chemistry experience.

A secondary common dictionary definition is to vanish gradually by evaporation. This is not commonly used in chemistry alone. Rather sublimation is used which implies it becomes a solid again somewhere else.

PE