KOLM Posted May 31 Posted May 31 Hi, Have some chromic acid and it is very damp as it is very hygroscopic. Does anyone know of a way to dry it out? Maybe over conc sulfuric acid or anhydrous calcium chloride? Could not find anything on the internet. Thanks.
chenbeier Posted May 31 Posted May 31 For what reason you want to dry it. It's a very poisson and cancerogene stuff. Normally it will be dissolved in water or sulfuric acid as etching compound. Drying with Phosphorous pentoxide is possible.
KOLM Posted June 1 Author Posted June 1 16 hours ago, chenbeier said: For what reason you want to dry it. It's a very poisson and cancerogene stuff. Normally it will be dissolved in water or sulfuric acid as etching compound. Drying with Phosphorous pentoxide is possible. Thanks, Chen. I need to dry it to avoid customers complaining about damp chromic acid. I guess I have nothing to loose from trying it, weigh up a small sample, the after a week reweigh. Might start with calcium (I dont have phos pentoxide handy, although a great choice.
exchemist Posted June 1 Posted June 1 19 hours ago, KOLM said: Hi, Have some chromic acid and it is very damp as it is very hygroscopic. Does anyone know of a way to dry it out? Maybe over conc sulfuric acid or anhydrous calcium chloride? Could not find anything on the internet. Thanks. Are you referring to chromium trioxide?
chenbeier Posted June 1 Posted June 1 (edited) 1 hour ago, exchemist said: Are you referring to chromium trioxide? Chromium-VI-trioxide CrO3 is called in publics mouth as chromic acid. If it get wet then it reacts to a sludge n CrO3 + H2O => H2(CrO3)(n-1)CrO4 With n= 2 for example it will be H2Cr2O7 Dichromic acid. Edited June 1 by chenbeier
exchemist Posted June 1 Posted June 1 15 minutes ago, chenbeier said: Chromium-VI-trioxide CrO3 is called in publics mouth as chromic acid. If it get wet then it reacts to a sludge n CrO3 + H2O => H2(CrO3)(n-1)CrO4 With n= 2 for example it will be H2Cr2O7 Dichromic acid. OK thanks.
KOLM Posted June 3 Author Posted June 3 On 6/1/2024 at 11:07 AM, chenbeier said: Chromium-VI-trioxide CrO3 is called in publics mouth as chromic acid. If it get wet then it reacts to a sludge n CrO3 + H2O => H2(CrO3)(n-1)CrO4 With n= 2 for example it will be H2Cr2O7 Dichromic acid. Wow, Chen, I didnt know. So, even if I were to dry it out some, it would not revert back to CrO3?
chenbeier Posted June 3 Posted June 3 (edited) 6 minutes ago, KOLM said: Wow, Chen, I didnt know. So, even if I were to dry it out some, it would not revert back to CrO3? Correct, it's difficult to keep it dry after open the container. Edited June 3 by chenbeier
KOLM Posted June 3 Author Posted June 3 2 hours ago, chenbeier said: Correct, it's difficult to keep it dry after open the container. Meaning, to clarify, once damp, it is not anymore CrO3, but a different compound H2Cr2O7 (?).
chenbeier Posted June 3 Posted June 3 CrO3, H2CrO4, H2Cr2O7, etc. All are chromic acid. On 6/1/2024 at 4:04 PM, exchemist said: Are you referring to chromium trioxide?
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