![]() (4) summarize in one sentence your answers to (1), (2), and (3)? Sometimes, however, bubbles appear at one electrode, and the masses of copper dissolved and deposited are not quite equal.Ĭonsidering everything in the solution, can you (1) identify the bubbles, (2) identify the electrode at which they appear, (3) write a half-reaction equation for what is occurring at that electrode, and It contains what you need to write these equations.)ī) State which half-reaction equation, (1) or $(2),$ represents the change at the electrode labeled " $ "$ in diagram (a) and which is the change at the "-" electrode.Ĭ) Which electrode, " " or "- " is the anode and which is the cathode in diagram (a)?ĭ) What ion or ions are carrying the charge through the electrolyte? From which electrode and to which electrode are they moving?Į) Ordinarily, this system operates at close to $100 \%$ efficiency, which means that 100 grams of copper dissolved at one electrode yields 100 grams of copper deposited at the other electrode. (Hint: Read the introduction to this question very carefully. The net operation of this system effectively transfers copper atoms from one electrode to the other.Ī) Write the oxidation and reduction half-reaction equations for the reactions that occur at the copper electrodes in diagram (a). Assume that diagram (a) represents one of the earliest known electroplating systems in which both electrodes are copper and the electrolyte is an acidic solution of copper(II) sulfate. $ Diagram (b) is completely labeled, but diagram (a) has almost no labels. IL.6 Draw the two lines corresponding to the redox couples of water on the Pourbaix diagram of copper (EP(OzHzO) = 1.23 V): Is metallic copper thermodynamically stable in aerated water? In deaerated water at pH = 7? in deaerated water at pH = 0?ġ year ago Problem II _ Pourbaix diagram of copperĮxamine Figure $19.1. Calculate the corresponding solubility product: ILS The vertical segment between domains 2 and corresponds to pH of 7.2. II.4 Determine the slope of the border between domains 1 and 2. IL.3 Identify the species corresponding to each of the domains 1-8. IL.2 AlL soluble species in the diagram have an octahedrally coordinated copper ion bearing water Or hydroxide ligands only: Give the complete formula ad name of the eight species included in the diagram: IL.1 Give the oxidation number of copper in each of the species included in the diagram: The Pourbaix diagram of copper for concentrations in soluble species equal to c=10 moL.L`, is given next page: The species represented in this diagram are (using simplified formula which correspond to the removal of water molecules) HCuOz, CuOz?, CuzOz, Cu?, CuO, Cu", CuzO, Cu. SOLVED: Problem II Pourbaix diagram of copper ![]()
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