What is the correct experimental setup to ensure the spoon is electroplated with silver?
Electroplating is a technique that can cover something in a thin layer of metal. In this case, we want to coat a spoon with a layer of silver metal. We can electroplate the spoon by placing it in an electrolyte solution. Electrolyte solutions contain ions. When electroplating, ions of the metal that we want to plate with need to be in the electrolyte solution. Since we would like to plate the spoon with silver metal, the solution must contain silver ions. This is why all of the experimental setups in the answer choices have aqueous silver nitrate as the electrolyte.
We also need another electrode to conduct electricity in the cell. The electrode should also be made of the metal we wish to plate with. Next, we’ll connect the silver electrode and the spoon to a power supply. When connected to the power supply, a redox reaction will occur. Oxidation will occur at the electrode attached to the positive terminal of the power supply. The silver metal electrode will be oxidized to form silver plus ions and electrons. The electrons will travel from the silver electrode through the external circuit. The electrons will arrive at the negatively charged electrode, which is the spoon.
The positively charged silver ions will be attracted to the negatively charged electrode. There, the silver ions will accept the electrons that traveled through the external circuit. This will cause the silver ions to be reduced, forming silver metal on the surface of the spoon. Over time, more of the silver ions in the solution will accept electrons. This will cause the silver metal to gradually disappear as it’s oxidized to form more silver ions. Eventually, a layer of silver will form on the spoon. We can see the experimental setup we’ve created clearly matches the diagram in answer choice (D). This is the correct answer, but it might be worth looking at the other answer choices to see why they won’t electroplate silver onto the spoon.
In answer choice (A), there is no silver electrode. The spoon is connected to the negative and positive terminal of the battery. To electroplate, we need two electrodes, one where oxidation can occur and the other where reduction can occur. Without two electrodes, the current from the power supply will flow in the circuit without any redox reaction occurring. In answer choice (B), the diagram has two electrodes, but the electrodes are connected by the spoon. This will cause a similar issue to what we saw in answer choice (A). It’s important when electroplating that two separate electrodes are used.
In answer choice (C), the spoon is the positive electrode, and the silver electrode is the negative electrode. We know that silver is plated onto the spoon as a result of silver ions in the solution being reduced to form silver metal. But oxidation occurs at the anode. So the spoon is the wrong electrode here. The spoon should be at the cathode or the negative electrode instead of the anode, the positive electrode. Finally, in answer choice (E), the spoon is resting at the bottom of the beaker. As we’ve said, silver ions are reduced at the negative electrode. So in this cell, the negative silver electrode will be electroplated instead of the spoon.
The correct experimental setup to ensure the spoon is electroplated with silver is answer choice (D).