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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: gaidzag on November 20, 2014, 07:39:36 PM

Title: Reacitivity of caesium ion?
Post by: gaidzag on November 20, 2014, 07:39:36 PM

I have been trying to understand why cesium hydroxide will eat through glass readily, while the the same molarity sodium hydroxide won't (or at least won't at the same rate).

1 M NaOH and 1 M CsOH both dissociate completely.  So the amount of hydroxide ion is the same.  So I'm guessing it's something about the cesium ion that makes it eat glass quicker, but what?  A good explanation would be much appreciated.

Title: Re: Reacitivity of caesium ion?
Post by: Borek on November 21, 2014, 03:20:03 AM

First time I hear about cesium hydroxide eating through glass faster than other hydroxides, do you have any reliable reference?

Title: Re: Reacitivity of caesium ion?
Post by: billnotgatez on November 21, 2014, 05:07:30 AM

http://en.wikipedia.org/wiki/Caesium_hydroxide

Seems to imply that cesium hydroxide is more reactive to silicon other hydroxides.
Unless I am reading it wrong.
I have to admit that after reading the WIKI article I was still puzzled.

Title: Re: Reacitivity of caesium ion?
Post by: Corribus on November 21, 2014, 10:31:40 AM

It appears to be electrochemical, and is useful for anisotropic etching of silicon (certain crystal planes etch faster than other). This isn't "indescriminate eating of glass" as the OP seems to indicate.

http://www-mtl.mit.edu/researchgroups/mems/people/schmidt/conferences/11.McNeilHHJune90.pdf

http://www.sciencedirect.com/science/article/pii/092442479280166Z