Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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chromium sulfate : Cr2(SO4)3 . 12H2O
aluminum sulfate : Al2(SO4)3 . 18H2O
cesium chloride : CsCl
potassium chloride : KCl
Class:
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elem=Al,K,Cr,Cs
precipitation
Summary:
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Cesium alums seem to be nearly insoluble compounds.
Description:
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Dissolve some chromium(III) sulfate in water, such that a dark blue/grey/violet
solution is obtained.
Dissolve some cesium chloride in a separate testtube.
Mix the two solutions: First, nothing seems to happen, but after a few seconds,
many small crystals are formed in the dark liquid and soon one can see a kind
of 'snow' falling out of the liquid. After a minute or so, the liquid has
become much lighter, it only is pale blue/grey/violet and there is a grey layer
of very fine crystals at the bottom.
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Dissolve some aluminium sulfate in water.
Dissolve some cesium chloride in a separate testtube.
Mix the two solutions: First, nothing seems to happen, but after a few seconds,
many small white crystals are formed. After a minute or so there is a white
layer of very fine crystals at the bottom.
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Repeat the same two experiments with the cesium chloride replaced by potassium
chloride: When this is done, there only is mixing of the liquids, no crystals
are precipitated and the liquids remain clear.