Sodium dichromate

Dichromates are very useful salts used in organic oxidations. They're also used for the preparation of chromic acid which is legendary for its effectiveness at cleaning glassware. The main 3 dichromates used in labs are potassium dichromate, sodium dichromate and ammonium dichromate. Working with dichromates is not risk free as most of them are potent carcinogens.

This is how I make sodium dichromate:

I start with about 27g of chromium(iii) chloride, which I dissolve in some water to form a green solution. I then pour bleach into the chromium(iii) chloride solution until the colour changes from green to yellow. Bleach (sodium hypochlorite solution) is a very strong oxidizer and it oxidizes the green chromium(iii) chloride to yellow sodium chromate. Next I add a bit of hydrochloric acid to the yellow sodium chromate solution until it turns to orange sodium dichromate.

Chromates, dichromates and trichromates exist in equilibrium with each other. They can be converted to one another by adjusting the ph: chromates = basic neutral, dichromates = acidic and trichromates = very acidic.

Anyway, the orange sodium dichromate solution can be boiled down to yield the sodium dichromate in crystalline form. This is what mine looks like:

2 CrO4-2 + 2 H+ <===> Cr2O7-2 + H2O