![]() In electrolytic cells, the direction of the applied voltage has no effect on the reaction or the site of the anode and cathode.ġ. When predicting an electrolytic reaction, the half-cell reactions are reversed prior to combining them.Ĩ.The calculated cell potentials in electrolytic cells can be positive.ĩ. In electrolytic cells, water is unreactive toward oxidation and reduction.ħ. In electrolytic cells, oxidation occurs at the cathode and reduction occurs at the anode.Ħ. No reaction will occur if inert electrodes are used.ĥ. Electrons move through electrolytes by being attracted to positive ions in the solution.Ĥ. The power source used in an electrolytic cell pulls electrons in at the negative terminal and pushes electrons out at the positive terminal.ģ. When identical electrodes are used in electrolysis, the same reactions occurs at both electrodes and the products are the same at both electrodes.Ģ. Student Difficulties (Misconceptions) with Electrolysis Associated with this Demonstrationġ. This demonstration, when paired with the electrolysis computer simulation, provides a great opportunity for students to experience the three levels of representation: microscopic, macroscopic, and symbolic (Johnstone's Triangle). Have students identify the flow of electrons into and out of the DC Power supply, the direction of ion migration in the cell, half-reactions occurring at each electrode, the cathode, the anode, and which electrode gains gains mass. ![]() Have students complete the electrolysis cell diagram as the instructor sets-up the demonstration. With respect to the active learning Class Activity, provide students with the "Electrolysis Model", physical constants, and an empty diagram of an electrolysis cell. We have found students understanding of electrolysis increasing when the details of electrolysis are introduced by first exploring a copper-copper electrolysis cell. Mentioning refining copper metal and showing a photo of refining copper metal by electrolysis helps to set the context for this activity. ![]() Explain to students this activity serves as an exercise to the principles of electrolysis because most students do not see any logical reason why one would want to plate copper metal onto a copper electrode. Students easily see and understand 1) the function of the DC Power Supply (forces electrons into the cathode and pulls electrons out of the anode) and what half-reactions occur at each electrode. This demonstration, accompanied with the Class Activity and Electrolysis Computer Simulation, serves well as an introduction to the basic principles of electrolysis. The effectiveness of this Electrolysis Cell demonstration can be enhanced when it is accompanied by an electrolysis cell computer simulation and computer animation at the particulate level (atom level). Table 17.7 Sample Data and Results of Calculations of a Copper-Copper Electrolysis Cell Reduction Half-reaction Students also can predict the moles of electrons passed, the moles of copper plated, and the mass of copper plated when the current is applied for half of the time. The actual mass obtained is compared to the theoretical amount calculated.ĭuring the operation of the electrolysis cell, students would work to calculate the theoretical mass of copper plated on the cathode. The time to plate the metal and the the current (amps) applied is used to calculate the theoretical amount of mass that should plate on the cathode. When the experiment ends, the electrodes are dried and the mass of each electrode weighed on the mini-balance. The cathode gains mass, the anode looses mass. Copper atoms on the anode are oxidized to copper(II) ions. When current is applied to the electrolysis cell copper(II) ions in solution are reduced to copper atoms at the cathode. The other Cu electrode is connected to the positive terminal of the D.C. The top of one Cu electrode is connected to the negative terminal of a D.C. The electrodes are placed in 1.0 M CuSO 4(aq) solution. Electrolytic Cell: A postage balance is used to measure the mass of two copper electrodes prior to the demonstration.
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