Via microwaves: Isolation of Thenard’s Blue

Content

A Little Bit about the history of the pigment Making of thenard's blue

Result

Thenard's Blue/ Cobalt Blue

Cobalt blue in impure form had long been used in Chinese porcelain, but was independently discovered as a pure alumina-based pigment

by Louis Jacques Thénard, in 1802Germany was also famous for production- especially the

Blaufarbenwerke ("blue-color works," in German) of Schneeburg. The dye is not to be confused with Prussian blue, which is an

intensely-blue pigment based on iron and cyanide, that contains no cobalt.

Isolation of Thenard's Blue

Thenard's Blue is a deep blue pigment, which is used as a colour for ceramics, due to it's chemical

resistance.Cobalt blue is toxic when inhaled or ingested.

Potters who fail to take adequate precautions when using cobalt blue may succumb to cobalt

poisoning

Procedure

Weight and mix 0.85 g of Cobalt-carbonate(CoCO

3), 1g

of Aluminium-oxide(Al

2O

3) and 2,75 g

of Potasium-chloride (Kcl) in a mortar

Put this mixture in a fire-proof container and cover it

Put it in the microwave (850W) for 5 minutes

After cooling, and crashing in the mortar, boil it in a baecker with 10 ml of Hydrochloric acid

Then wash it with 25 cl of water → solid is filtrated and dried

Procedure

Observations and evalution

The Educt-mixture is dark gray → a deep blue powder → colour becomes more intensive after

boiling with Hydrocloric acid

CoCO3 + Al

2O

3 → CoAl

2O

4 + CO

2

Thank you for the attention it was fun to work on this project for us we hope we haven't bored you :)