Osmium(VIII) catalysed oxidation of antimony(lll) by alkaline Hexacyanoferrate(lll) and analysis of osmium{VIII) in microamount by a kinetic method

Abstract

The osmium(VIll) catalysed hexacyanoferrate(lll) oxidation of antimony(lll) in aqueous alkaline medium at 25°C obeys the rate law<br><img src='http://www.niscair.res.in/jinfo/equation55.gif' border=0><br>

where <i>K</i>₂ is the equilibrium constant for the reaction<br> <img src='http://www.niscair.res.in/jinfo/equation56.gif' border=0><br> <i>K</i>₃ is the formation constant for the complex formation between alkaline species of osmium(Vlll) and hexacyanoferrate(lll) and <i>k </i> is the rate constant of the slow step. The data suggest that the reaction goes through catalyst-oxidant complex formation followed by the reaction of substrate with complex in the rate determining step. The reaction constants involved in the mechanism are derived. The title reaction has been utilised for the analysis of osmium(Vlll) in the range 0.019 <i>µ</i>g cm^-3 to 0.66 <i>µ</i>g cm^-3.