A Rapid Color Test for Electrical Polarity
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There often arises a. need far a simole and rauid test for electrical uolaritv (i.e... . and U,uallg x volrmerer i. rvailahl~1t.r such purposes, I N I ~failing chi>,ptrlarity can be drrrrthat 111" red113. avniI~I~Ie it) every miwd Ly u simple rolur teat i&p; rir1.w trd papels ,,I. rcage111~ chemical laboratory. The test is performed as follows: Test leads connected to the terminals in question are placed about 1cm apart on a piece of wet test paper or on a strip of filter paper wet with aqueous solution containing about 10yoreagent. -").
Wet Test Paper Lead acetate PhenoInht,hxlein Wid,
Color (Polarity) Black (-) Red 1 - \
Filter Paper Wet with Reagent NsCl NaRr
h
Color (Polarity) Green (+) Orange (+I Brown (+) Lime-Green i+j
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A wlor is developed at either the or "-" lead as a result of electrochemical oxidation or reduction (see table). The test can be performed for voltages as low as 2 5 V but is most dramatic and rapid s t voltages above 1 V. Polarity determination for a potentiostat can be made by connecting reference electrode to working electrode and testing between working and counter electrodes. Many other reagents and test papers can be used for this t e s t t h e only criteria being color development as a result of eleetro-oxidation or reduction.
Volume 48, Number 4, April 1971
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