It is observed that when solid copper is added to a solution containing gold ions, the

copper dissolves and the gold precipitates. Similarly, almost every other metal will displace gold from solutions of gold salts.

a. Do these results mean that the gold ion is an unusually good oxidizing agent or poor oxidizing agent? Explain.

b. High end stereo units use gold coated parts. Is the choice of gold based solely on its appearance or can its choice be based on its chemical behavior (reactivity) also? Explain.

I think a is a poorly worded question. Au is a poor reducing agent; Au(III) ion is a good oxidizing agent.

The use of Au in high end stereo units (I have one with Au coated parts) because Au coated contacts resists oxidation by air.

a. To determine whether the gold ion is a good oxidizing agent or a poor oxidizing agent, we need to understand the concept of oxidation and reduction reactions. In an oxidation-reduction (redox) reaction, an oxidizing agent gains electrons while the reducing agent loses electrons.

In the given observation, copper (Cu) dissolves while gold (Au) precipitates. This indicates that copper is being oxidized, becoming a Cu2+ ion in the solution, while gold is being reduced, forming solid gold. In this case, gold is acting as the reducing agent because it is gaining electrons, and copper is the oxidizing agent because it is losing electrons.

Based on these observations and the tendency of various metals to displace gold from solutions of gold salts, we can conclude that gold ions are a poor oxidizing agent. If gold ions were a good oxidizing agent, they would not be displaced by other metals in this manner.

b. The choice of using gold-coated parts in high-end stereo units can be based on both appearance and chemical behavior. Gold is well-known for its lustrous and appealing appearance, which adds to the overall aesthetic value of the stereo unit.

Additionally, gold has excellent resistance to corrosion and oxidation, making it highly suitable for electronic applications. It does not react readily with oxygen, moisture, or most chemicals, ensuring that gold-coated parts remain intact and do not degrade over time. This chemical behavior of gold makes it highly reliable for maintaining the quality and performance of the stereo unit.

Therefore, while the choice of gold may initially be influenced by its appearance, its chemical behavior, particularly its high resistance to corrosion, also makes it a valuable choice for electroplating and coating purposes in high-end stereo units.