Quinone can be reduced to hydroquinone with an excess of electrolytically generated Sn(II):

The polarity of the working electrode is then reversed, and the excess Sn(II) is oxidized with Br2 generated in a coulometric titration:
Sn2+ + Br2 ( Sn4+ + 2 Br¯
Appropriate quantities of SnCl4 and KBr were added to a 50.0-mL sample. Calculate the mass of C6H4O2 in the sample from the data:

Transcribed Image Text:

OH + Sn4+ OH quinone hydroquinone Working Electrode Functioning As Cathode Anode Generation Time with Constant Current of 1.062 mA, min 8.34 0.691