Chemical Speciation in the Copper (I)-Ammonia-Chloride System

Abstract

Chemical speciation in the system Cu^I/NH₃/Cl- which may be represented by the general equilibrium pCu^I(aq)+qNH₃(aq)+rCl-(aq)↔ Cu_p(NH₃)_qCl_r(p-r)+(aq) has been studied by glass electrode potentiometry at 25.0°C and an ionic strength of 1.00 M (NaClO₄). A number of binary and ternary complexes were detected with formation constants, β_pqr: logβ120 = 11.381±0.077, logβ₁₁₁ = 8.920±0.045, logβ₁₁₂ = 8.82±0.18 and logβ121 = 11.33±0.24. The ionization constant of water (pK_w) and the protonation constant of ammonia (pK_a) obtained by the same procedures were 13.7462±0.0012 and 9.4613±0.0010 at I = 1 (NaClO₄), and 13.7165±0.0010 and 9.4521±0.0007 at I = 1 (NaCl) respectively.