Sciencemadness Discussion Board

Al2(Cr2O7)3

Admagistr - 26-5-2023 at 13:45

Has anyone made this compound?I am considering mixing a solution of Al2(SO4)3+K2Cr2O7. I'll take a picture and post how it turned out...There is a post on the forum about making gallium chromate and it was stated that it is probably a mixture of chromate and dichromate,or dichromate because the gallium salts are acidic,so it could work for aluminium as well...I asked Bedlasky,but he didn't make aluminium dichromate,so he has no practical experience with it...

MidLifeChemist - 27-5-2023 at 15:03

I've made neodymium dichromate, it is a very interesting compound with some cool properties

Admagistr - 27-5-2023 at 15:36

Quote: Originally posted by MidLifeChemist  
I've made neodymium dichromate, it is a very interesting compound with some cool properties


That sounds very interesting, can you please write more about its production and characteristics or provide a link?I guess it will be interesting in color and maybe it will change color depending on the type of light?Thanks!

Rainwater - 28-5-2023 at 08:17

Quick google turned up this
React Aluminum Nitrate Reacts With Potassium Dichromate
$$ 2Al(NO_3)_3(aq) + 3K_2Cr_2O_7 \rightarrow 3Al_2(Cr_2O_7)_3(s) + 6KNO_3(aq)$$

Edit:
Cant find any good thermodynamics data for the compounds but it will likly be very exothermic

[Edited on 28-5-2023 by Rainwater]

Admagistr - 28-5-2023 at 17:56

Quote: Originally posted by Rainwater  
Quick google turned up this
React Aluminum Nitrate Reacts With Potassium Dichromate
$$ 2Al(NO_3)_3(aq) + 3K_2Cr_2O_7 \rightarrow 3Al_2(Cr_2O_7)_3(s) + 6KNO_3(aq)$$

Edit:
Cant find any good thermodynamics data for the compounds but it will likly be very exothermic

[Edited on 28-5-2023 by Rainwater]


Thanks for the tip,probably it would be better to use nitrate or aluminium chloride,Bedlasky was thinking that KAl(SO4)2.12H2O could be precipitate when using sulphate.Aluminium dichromate could be interesting to reduce with aluminium powder and produce chromium,maybe some rubies would be formed,which sometimes appear when reducing Cr2O3+Al.I found information that Al2(Cr2O7)3 is used in pyrotechnics.