Does Boric Acid Expire ??? or become B2O3 after 5-10 years on its own???

mubashirmansoor

Hi,

I have had some Boric acid (99.9%) bought a very long time ago... The expiry date was in 2006...

I have used it recently and it is as if it's pure B2O3. Is that even possible??!! How could it be???! or is there something I am missing?

The experiment I had done was heating some of this Boric acid along with certain glass modifiers (Na2O and PbO) and the density as well as other optical properties of resulting glass are as if I have used B2O3 in the batch. There hasn't been any weight loss associated with the decomposition of Boric acid either!

thanks in advance...

Dr_Morbius

When kept at room temperature Boric Acid should last forever. Sometimes though the term "Boric Acid" can be applied to more than one chemical so you should check the label and see what the chemical formula on it says.

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

mubashirmansoor

its Analytic grade H3BO3...

It has been at room temperature in a poorly sealed plastic container.

Borek

When heated, boric acid starts to decompose below 200°C, I don't see how it could not lose the water - unless it reacted with Na₂O present. Perhaps properties of the glasses you are referring to have error margins wide enough so that they are not an indicator of what have really happened?

To answer directly your question: no, it won't expire nor change to B₂O₃, it is quite stable.