Experiment #2: Mg + CuCl2 (aq)
<Missing Picture Palko>
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Experiment #6: Cl- (aq) + CuCl2 (aq)
CuCl42-(aq) + 4 H2O(l) <--> Cu(H2O)4 2+ (aq) + 4 Cl- (aq)
Addition of chloride ion shifts the equilibrium reaction to produce more CuCl42-(aq) which is a green solution as shown in the beaker on the right above. Cu(H2O)4 2+ (aq) is a blue solution.
Work done in 2009:
Experiment #1: Addition of OH- (aq) to CuCl2 (aq)
Addition of sodium hydroxide solution dropwise to aqueous copper (II) chloride solution (#1), which exists as Cu(H2O)42+ (aq) and Cu(H2O)4OH- (aq), produces initially a light blue-white precipitate that is suspected to be an aqua chloro hydroxy cuprate compound (#2). Upon continued addition of OH- and removal of the initial precipitate by centrifuging, a darker blue precipitate forms that according to references is Cu(H2O)4(OH)2 )(#3). Upon standing in air or in solution, Cu(H2O)4(OH)2 converts to black CuO as seen as black flecks above (#4).
Overview of the Project:
In 2008, students in Mr. Palko's AP Chemistry class were conducting a simple experiment illustrating the reaction of magnesium metal and copper (II) ions. Instead of using copper (II) nitrate as called for in the lab prep instructions, Mr. Palko substituted copper (II) chloride due to the excess of this reagent in the I.H.S. stockroom. A number of unexpected reaction products were observed until the copper metal product was ultimately obtained. Brittany Buterbaugh, an Indiana University of PA chemistry student, investigated the reaction as part of a project. In 2009, the advanced chemistry class has continued the project.
Click here to download Brittany's report
Click to go to a great site about transition metal chemistry
Note: All photos can be viewed at a respectable size in the Photos section.
Experiment #3: Mg + CuCl2 (aq) in a citrate buffer
Orange product separated from copper metal product
Experiment #4: Al + CuCl2 (aq)
Green Product after evaporation of water after reacting aluminum metal with CuCl2 (aq).
Experiment #5: Heat + CuCl2 (aq)
CuCl42-(aq) + 4 H2O(l) <--> Cu(H2O)4 2+ (aq) + 4 Cl- (aq) + heat
This reaction is exothermic in the forward direction as written above. Heating blue Cu(H2O)4 2+ (aq) shifts the equilibrium reaction above to produce more reactant, green CuCl42-(aq).
