According to the standard activity series, would solid nickel be readily oxidized in an aqueous sodium sulfate solution?

• A. True
• B. False
• C. Not enough information
• D. Only at high temperatures

Answer: (B)

The standard activity (electrochemical) series tells you which metals will lose electrons in a given aqueous environment by comparing how readily they can be oxidized relative to the available oxidants in solution. For nickel to be oxidized, there must be an oxidizing species in the solution that can pull electrons away from Ni metal.

In an aqueous sodium sulfate solution, there isn’t a strong oxidizing agent present. Sulfate ions are not good oxidizers under standard conditions, and water (the common oxidant in such solutions) does not spontaneously oxidize nickel at room temperature in the absence of a driving force like electrolysis or a much stronger oxidant. The Ni2+/Ni couple has a relatively negative tendency to remain reduced, but without a stronger oxidant in solution, nickel stays as solid nickel rather than dissolving as Ni2+.

So, nickel would not be readily oxidized in this solution. Some very slow corrosion could occur if oxygen is present, but that is not considered a readily favorable oxidation in a simple sodium sulfate solution.