Solubility of Cu

Fig. 10.5. TTT diagram for the precipitation of CuAh from the Al + 4 wt% Cu solid solution. Note that the equilibrium solubility of Cu in Al at room temperature is only 0.1 wt% (see Fig. 10.3). The quenched solution is therefore carrying 4/0.1 = 40 times as much Cu as it wants to.

The low solubility of Cu oxide and hydroxide minerals and relatively high solubility of its carbonate cause the preferred association of Cu with the oxide phases, such as CuFe204j that may determine the solubility of Cu2+ in soil solution (Lindsay, 1979). In soils with high pH, lead carbonate (PbC03 (cerussite)) is stable, but its solubility is still higher than that of Pb phosphates. 

Since the solubility of Cu(OH)2 is only 58 /zg/ml [45], essentially all the Cu2+ ions in the solution immediately precipitate out of the solution. If the addition of aqueous ammonia solution is continued, however, a second reaction takes place. The excess ammonia molecules react with the Cu(OH)2, forming a new complex species that is highly soluble ... 

Thus, the solubility of Cu(OH)2 is ca 10 times greater than that of CuO. The inversion of Cu(OH)2 into CuO should occur exergonically. However, if CuO is very finely... 

The aqua Zn ion is dominant in organic matter-free freshwater while the free Zrf+ ion and chloride complexes dominate in seawater (Stanley and Byrne 1990 Millero 1996). The free Cu + ion is dominant in freshwater, while the carbonate complexes CuCO, and [Cu(C03)2] are preponderant in seawater. Speciation and solubility of Zn in Cl-rich hydrothermal solutions has been investigated by Wesolowski et al. (1998). Speciation and solubility of Cu have been investigated by Mountain and Seward (1999) for hydrothermal solutions dominated by sulfides and by Xiao et al. (1998), Liu et al. (2002), and Archibald et al. (2002) for solutions dominated by chlorides. 

The different degrees of passivation may be related to the solubility of Cu(inhibitor) complexes. Cu is known to readily form complexes with BTA, PVI-1, and UDI [3, 30]. The charge balance for PVI-1 indicates that the passivating layer, at least for PVI-1, is partially soluble. It is known that Cu-PVI-1 and Cu-UDI complexes are soluble in 0.3M HCl [23,20]. This may explain why no such passivation is observed at pH=1, although the absence of copper oxide formation processes is also relevant. 

Fig. 2 distinguishes the domains of immunity, corrosion and passivity. At low pH corrosion is postulated due to an increased solubility of Cu oxides, whereas at high pH protective oxides should form due to their insolubility. These predictions are confirmed by the electrochemical investigations. The potentials of oxide formation as taken from potentiodynamic polarization curves [10] fit well to the predictions of the thermodynamic data if one takes the average value of the corresponding anodic and cathodic peaks, which show a certain hysteresis or irreversibility due to kinetic effects. There are also other metals that obey the predictions of potential-pH diagrams like e.g. Ag, Al, Zn. 

Nonideal solid-liquid TX diagram at 1 atm for Cu and Al (only about the left half of the diagram is shown). The two-phase regions are indicated. There is a very limited solubility of Cu in Al this is phase a. There is similarly a limited solubility of Cu in the stoichiometric phase or intermetallic compound CuAI2 (called the 6 phase). The liquid solution of Al in Cu freezes at the lowest possible temperature ( 540°C) for 32 mass % Cu this is the eutectic point (which is technologically useful in solders). 

Whereas the solubility of Cu in aluminum metal is ca. 5 wt% at temperatures in excess of 500°C, the solubility drops to ca. 0.1 wt% at room temperature. Hence, a metastable alloy is present when the high temperature alloy is rapidly quenched. Subsequent annealing will result in further strengthening similar to what we discussed for martensite. The strengthening effect is thought to occm due to the formation of Cu-rich discs (approx, diameter of 100 atoms, and thickness of ca. 4 atoms) that align themselves preferentially with selected planes of the host A1 lattice, causing coherency strains within the solid-state structure. 

To find the solubility of Cu(I03)2, we must find the equilibrium concentrations of the Cu2+ and I03 ions. We do this in the usual way by specifying the initial concentrations (before any solid has dissolved) and then defining the change required to reach equilibrium. Since in this case we do not know the solubility, we will assume that x mol/L of the solid dissolves to reach equilibrium. The 1 2 stoichiometry of the salt means that... 

There is a competition between dissolution of the mechanical abraded material in the slurry and redeposition back on the abraded surface. Derive an expression for the removal rate of copper as a function of the polish parameters, solubility of Cu or passivated Cu in die slurry, and the redeposition factor. 

The iodide ion not only serves as a reducing agent, but also exerts an enormous influence on the potential of the Cu(II)-Cu(I) couple because of the slight solubility of Cu(I) iodide = 10" ). Cu(I), which is not stable in water at appreciable concentrations, owing to its diqiroportionation into Cu(II) and metallic copper, is stabilized by the formation of Cu(I) iodide. The half-reaction... 

Example 7.14. Solubility of Cu(II) in Natural Water Effect of Complexing by Carbonate Estimate the solubility of Cu(II) in carbonate-bearing water of constant Cj = 10 M (closed system). The pertinent Cu(II) equilibria are given in Table 7.3. 

Figure 7.16. Solubility of Cu(II), (a) Activity ratio diagram, (b) Solubility diagram. The solid line surrounding the shaded area gives the total solubility of Cu(II), which up to a pH value of 6.96 is governed by the solubility of malachite [Cu2(0H)2C03(s)]. In the low pH region, azurite [Cu3(OH)2(C03)2(s)] is metastable but may become stable at higher C-j- Above pH 7, the solubility is controlled by the solubility of CuO (tenorite). The predominant species with increasing pH are CuC03(aq), Cu(C03)2 , and...

The solubility of copper in natural waters in acid media is limited by the solubility of the alkaline carbonate, malachite Cu2(0H)2C03, and in the alkaline media by the solubility of Cu(OH)2. However, it depends on the concentration of hydrogen carbonates. Depending on pH and hydrogen carbonates, only limited quantities of copper can be kept in the soluble form, this being of practical importance for the evaluation of its algicidal effects in reservoirs. 

The Cu-Au system is the classic textbook example for discussing ordering reactions in solid solutions and the effects of atomic order on properties (see, e.g., Schulze, 1967 Honeycombe, 1968). At higher temperatures above 410 °C the Cu-Au alloys form the disordered Al structure with complete mutual solid-solubility of Cu and Au, whereas at lower temperatures ordering reactions occur which produce various intermetallic phases, depending on temperature and composition, with broad... 

We can estimate the diffusivity of Cu(acac)2 in CO2 from the slope in the released-mass line with respect to Vt if is known. In this experiment, d>o is the equilibrium solubility of Cu(acac)2 in CO2 at the given condition. Table I summarizes the obtained diffusivity and data used for estimation. The solubility of Cu(acac)2 in liquid CO2 was calculated by the equation of the state suggested by Cross, et al.[2l ]. The difilusivities obtained in the liquid and the supercritical states are in the range of the value of the self-diffusion coefficient of CO2 [1,22,23]. 

Water-in-C02 microemulsion was used to dissolve metal salts in the production of nanoparticles via RESOLV. In order to evaluate the solubility of Cu(N03)2, for example, the same microemulsion as that used in the rapid expansion was prepared in a high-pressure optical cell. With Cu(N03>2 in the water phase, which exhibited the distinctive blue color of aqueous Cu (70), the microemulsion appeared homogenous. According to the observed absorbance (the band centered at 740 nm), the Cu(N03)2 salt was completely dissolved in the PFPE-NH4-stabilized water-in-C02 microemulsion. The other metal salts were similarly soluble, resulting in microemulsions that appeared equally homogeneous. 

The Cr effect on the solubility of Cu in austenite of mild steel at 900, 1100 and 1250°C was studied by [1967Sal]. The measured solubility of Cu in Fe based phases is slightly lower compared with the results of [19970ht, 2002Wan], and a slight minimum of the solubility upon addition of about 5-6 mass% Cr was found. The minimum point of Cu solubility in Fe based solid solution, reported by [1967Sal], was not confirmed by the calculation for the Cr-Cu-Fe system. 

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