No abstract

The reaction of peroxomonophosphoric acid and hydrazinium ion in acid perchlorate solutions occurs as per stoichiometry (i), and the rate law (ii) at large [NzH~'], -d[HaPOs]/dt = [H~PO~]T[H+] (ki + kz[NzHs+]/(K& + [H']))where K& is the first acid dissociation constant of H3P05 and kl and kz are rate constants found to be 2.6 x s-' and 5.0 x lo-' M-' s-', respectively, at 35". The reaction is greatly catalyzed by iodide ions. The mechanism involves a redox cycle 1-/12 and the rate is independent of [N2H5'] in the presence of iodide ions. K& was found to be 0.55 M-' and independent of temperature. Experimental MaterialsSolutions of PMPA were prepared each day whenever required by the hydrolysis of peroxodiphosphate in 0.5 M HC1O4 at 45" for about 1.5 h. It was standardized iodometrically. Solutions of lithium perchlorate were prepared by neutralizing 70% HC1O4 (E. Merck) with BDH AnalaR lithium carbonate

The title reaction is found to occur according to the stoichiometry outlined in the scheme. At high N2H+ 5 concentration, the reaction follows the rate law -d(H3PO5)/dt = (H3PO5)T(H+)(k1 + k2(N2H+ 5)/(K'd + (H+))) with k1 = 2.6·10-4 s-1 and k2 = 5.0·10-2 M-1 s-1 at 35 • C (Kd: first acid dissociation constant). The reaction is greatly catalyzed by Iions. The mechanism involves a I-/I2 redox cycle and the rate is independent of (N2H+ 5). -(AMALA DHAS, T. P.; MISHRA, D. K.; MITTAL, R. K.; GUPTA, Y. K.; Int. J. Chem. Kinet. 23 (1991) 3, 203-213; Dep. Chem., Univ. Rajasthan, Jaipur, India; EN)