Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
-----------------
diethyl ether : CH3 CH2 O CH2 CH3
acetone : CH3 CO CH3
ammonium thiocyanate : NH4SCN
cobalt chloride : CoCl2.6H2O
Class:
------
elem=Co
coordination
Summary:
--------
Cobalt builds highly colored complexes with thiocyanate when acetone
is added. This complex is soluble in ether.
Description:
------------
Dissolve some CoCl2.6H2O in water and add a solution of NH4SCN: The liquid
remains pink, but the color becomes more intense.
Add some acetone, approximately the same volume as the volume of the aqueous
solution with cobalt and thiocyanate: The resulting liquid turns blue/cyan.
The color is exceedingly intense. When the liquid is shaken, then the liquid,
which sticks to the glass turns the glass deeply cyan. A layer of approxima-
tely 1 cm is opaque. This dark liquid is called DARKCYAN.
Add some ether to DARKCYAN and shake well: A two-layer system is created
after some time, needed to settle. The bottom layer is an intensely colored
aqueous layer and the top layer is the ether-layer, which has a strong
cyan color, although not as intense as the aqueous layer.
Add a lot of water to the two-layer system (approximate 10 times the volume
of the aqueous layer is added): There is still a two-layer system. The bottom
layer is pink and the top layer is colorless.
Add water to DARKCYAN, drop by drop, while shaking after each drop: The liquid
remains deep blue/cyan after addition of a large number of drops, until a
certain point is reached, where the color suddenly changes. From this point
only 5 drops are needed to change color from intense blue/cyan to dirty-pink.
The color transition goes from deep cyan to dirty-blue to dirty-pink. Adding
more drops of water makes the pink color more 'fresh', less 'dirty'/brownish.