Studies on the composition and kinetics of chromium(III)-alanine system

✍ Scribed by Iqrar A. Khan; Kabir-Ud-Din

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 396 KB
• Volume: 17
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550171203

✦ Synopsis

Kinetics of the complex formation of chromium(II1) with alanine in aqueous medium has been studied a t 45, 50, and 55"C, pH 3.3-4.4, and p = 1 M (KNOJ. Under pseudo first-order conditions the observed rate constant (kabs) was found to follow the rate equation:

Values of the rate parameters (k,,, kin, KIP, and Kip) were calculated. Activation parameters for anation rate constants, AHf(k,,) = 25 * 1 k J mol-', AH'(kL,) = 91 2 3 kJ mol-', and AS'(k,,) = -244 2 3 JK-' mol-', AS'(k:,) = -30 2 10 JK-' mol-' are indicative of an (I,) mechanism for k,, and (Id) mechanism for k;, routes (. , substrate Cr(H,O)i' is involved in the k route whereas Cr(HzO),0H2' is involved in k' route). Thermodynamic parameters for ion-pair formation constants are found to be AHo(KIP) = 12 2 1 k J mol-', AH"(K6) = -13 2 3 kJ mol-' and ASo(KIp) = 47 ? 2 JK-' mol-', and AS"(K;p) = 20 9 JK-' mol-'.