Indium Chemistry: Indium Chromate vs Dichromate

This is our second season of videos and we are always trying to find more stuff, to get more stuff and to show more stuff on YouTube. In the end, we want to build up a huge collection about some of the most famous and some unknown or even lost experiments for every (possible) element in the PSE. At some point, you cross elements and compounds you never saw before. One is Indium. While some people might recall Indium itself especially its blue emission or the use in for example Indiumarsenide real, colourful chemistry with indium is nothing you usually find in your chemistry books.

We bought this bottle of In2(SO4)3 a while ago. It is a mediocre soluble, white powder but we never had any ideas what to use it for. As we were looking for another compound, we came across this bottle again and gave it a try.

Therefore, here is an interesting Indium related experiment:
If you add an Indium(III) solution to a Chromate it will precipitate, if you however use Dichromate it won't. The reason why this happens is still not fully understood. Tests show that in fact no In2(CrO4)3 forms but In(OH)3 which is abled to absorb Chromate in solution on its surface colouring it yellow. Many other insoluble Indium compounds have been proven to consist of In(OH)3 with other stuff absorbed on its surface as well.

We will review this problem in the Indium Cyanide video again.