Solvent extraction equilibria in tne rhodium (Ill)-salicylhydroxami acid system

Abstract

A detailed study of the extraction equilibria of rhodium (III) by the hydroxamic acid solution in isobutyl alcohol from aqueous chloride medium is described. The percentage of metal extracted has been determined by UV-visible spectrophotometry. The extracted species is established to be RhL₃. The reaction equilibrium constant ‘<em>K</em>_ex<em>' </em>for the reaction,<br><br> Rh³⁺ + 3HL₍₀₎ <img src="http://www.niscair.res.in/jinfo/equation66.gif" alt="" border="0" /> RhL₃₍₀₎+ 3H⁺<br><br> Has been found to be 10-9.744 at an ionic strength of 0.01<em>M</em> (NaCl). The <em>p</em>H_1/2 of the extraction for this system is found to be 5.14. The stepwise stability constants of the complex have been determined from the experimental data using Leden’s method and the values are 2.505, 2.398 and 2.875 for log <em>k</em>₁, log <em>k</em>₂ and log <em>k</em>₃ respectively.