Transition of indicators

Colour transitions of indicators Acid-alkali and iodometric/iodimetric titration Pipetting technique... 

In molten nitrates such transition was observed only for phenolphthalein (yellow-purple), other indicators seemingly were oxidized by the melt (the conclusion made was insoluble in the melt ). In molten KSCN not possessing oxidizing properties color transitions were observed for all indicators used (methyl red, fliymolphthalein, etc.). The employment of indicators for acidity estimation is limited mainly by their thermal instability and tendency to oxidize at high temperatures. Since ionic melts, as a rule, have no constitutional water, the reverse transition of indicator into the protonized form [10.4.24] is hardly possible (the solution of phenolphflialein became yellow at the reverse transition base-acid ). 

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See also in sourсe #XX -- [ ]

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