The kinetics of the dissolution of copper in stirred oxygen-containing solutions of ethylenediamine and several amino acids have been examined and com~ pared with those found earlier for ammonia. In each case, provided that the partial pressure of oxygen exceeds a critical value (below which its transport to the copper surface may be rate limiting), the rate was found to be zero-order in oxygen and first-order in the complexing agent. The rate-determining process is believed to be the chemical attack of the oxygen-covered copper surface by the complexing agent. At 25 ~ the rate constants for dissolution by ethylenediamine, glycinate, ~-alaninate, and ~-alaninate were found to be 2.3 x 102, 49, 59, and 11 mg Cu cm -2 hr -1 M -1. These follow the same order as the stability constants of the corresponding cupric complexes. In each system there is also another reaction path, independent of the first, which involves the protonated species, i.e., the ethylenediaminium ion and the neutral amino acids. The corresponding rate constants are 5.1 x 102, 31, 36, and 3.5 mg Cu cm -2 hr -1 M -1.A kinetic study of the dissolution of copper in oxygen-containing aqueous solutions of ammonia and ammonium salts was described earlier (1, 2). It was shown that the reaction proceeded by two independent paths whose rate-determining steps are the chemical attack on the oxygen-covered copper surface by an NH3 molecule and an NH, § ion, respectively. Both rates are independent of the oxygen concentration above a critical value when the transport of oxygen to the surface is no longer ratelimiting. Under these conditions the kinetics are of the form Rate = kA[NH3] + kAR[NH~ § [1] At lower oxygen partial pressures a different rate law, first-order in oxygen and independent of the concentrations of ammonia or ammonium salts, was observed; this was attributed to rate control by oxygen transport.The present paper describes similar measurements using several other complex-forming reagents, notably the chelating agents ethylenediamine, glycine, a-alanine, and fl-alanine. These were selected with a view to providing further insight into the role of complex formation in the mechanism of the dissolution process and to correlating the rate of dissolution with the structure and stability of the complexes formed. ExperimentalThe apparatus and experimental procedure were similar to those employed earlier (1, 2) with the following minor variations: Agitation was effected by means of a turbine-type impeller whose blades, generally rotating at 770 rpm, swept a cylindrical volume of 8 cm diameter. The exposed surface (generally about 2 cm 2) of the Bakelite-mounted copper specimen was positioned in a vertical plane tangential to this cylindrical volume.Most of the measurements were made using conductivity-grade (99.97%) copper; no difference in the rate of dissolution was noted when JohnsonMatthey high-purity (99.999%) copper was used instead. Different annealing pretreatments, which resulted in grain sizes ranging from 0.035 to 0.12 ram, were also without e...

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Experimental evidence is presented which shows that upon neutron irradiation of the compounds Mn2(CO)10, CpMn(CO)3, and CH3CpMn(CO)3 the recoiling 56Mn atom gathers carbonyl radicals to stabilize itself in the group Mn(CO)5, with about 10% radiochemical yield. Basically, the experiments involved addition of iodine to the irradiated compound and identification of the radioactive IMn(CO)5 by carrier techniques. It is suggested that in Mn2(CO)10 targets, the species produced is the •Mn(CO)5 radical itself. Some experimental data are given to show that this radical is stable for over 1 h in the solid at room temperature, but decomposes rapidly above about 60°. The radical decomposes in 20–30 s in solution. In both other target compounds, the species produced is chemically more stable, although it reacts rapidly with iodine. This species is found to be HMn(CO)5, which occurs to the extent of 10–12% in CpMn(CO)3. CH3Mn(CO)5 was also detected in CH3CpMn(CO)3 targets, and its yield was found to be a function of the concentration of isooctane used as diluent in the targets.Results from other studies are discussed in the light of the present data, and it is concluded that in general, in neutron-irradiated metal carbonyl compounds, the recoil atom is able to accumulate carbonyl radicals to a greater extent than is consistent with the composition of the target compound.

The Knudsen effusion method has been applied in a study of the vapor pressures of manganese in equilibrium with copper-manganese alloys a t high temperatures. The amount of manganese effused was determined by the use of radioactive Mnj4. The odd behavior noted in this system a t 20-3070 Mn, observed in a number of studies of various physical properties, has been observed once more in the apparent activity of manganese. Some discussion is given of the Knudsen effusion method, particularly regarding some possible sources of error.

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