Video Transcript
The diagram shows the purification of copper. What are the correct labels for this experiment?
This diagram shows the last step in the purification of copper. Copper is obtained from mining copper ore. However, copper ore is not made of copper metal. Rather, copper ore is made of copper-containing compounds, such as copper sulfides, copper oxides, and copper phosphate. Copper metal is then extracted from the copper ore. This process will look different depending on which copper-containing compounds the copper ore was made of. However, this metal that is extracted from the ore still contains a number of impurities. Depending on how this copper metal is intended to be used, these impurities might be okay. But pure copper metal is needed for certain applications, such as in electronics.
To purify the copper metal, we’ll use this experimental setup, which shows an electrolytic cell. In an electrolytic cell, a redox reaction is powered by an external power supply. The power supply will cause the impure copper metal to be oxidized, forming copper ions. These copper ions can then be reduced at the other electrode in the cell, forming pure copper metal. As the experiment continues, the impure copper metal will be used up, leaving behind any impurities. However, some impurities in the impure copper metal might also be oxidized in the electrolytic cell and plated along with the copper metal. As a result, the copper metal we obtain from this process is not 100 percent pure, although it is significantly more pure than the metal we start off with.
So, given what we know about this process, let’s try to label this diagram. We know the impure copper metal will be oxidized. Oxidation always occurs at the anode of an electrochemical cell. So we know this electrode is the one that’s made of impure copper. The process of reduction occurs at the cathode. So this is where copper ions will be reduced to form copper metal. So we know this electrode must be the one made of pure copper.
The last thing we need to label is B, which is pointing to the solution in this cell. When performing an experiment like this, we need a solution that contains ions, which is called an electrolyte. Specifically, we’ll need a solution that contains copper ions, as copper ions in the solution will be reduced at the cathode to form copper metal. A copper sulfate solution will be a good choice for the electrolyte in this experiment, as sulfate ions will not react in the cell. So the correct labels for this diagram that shows the purification of copper is A pure copper electrode, B copper sulfate electrolyte, and C impure copper electrode.
