Chapter 4, Problem 131AP

Give a chemical explanation for each of the following: (a) When calcium metal is added to a sulfuric acid solution, hydrogen gas is generated. After a few minutes, the reaction slows down and eventually stops even though none of the reactants is used up. Explain (b) In the activity series, aluminum is above hydrogen, yet the metal appears to be unreactive toward hydrochloric add. Why? (Hint: Al forms an oxide. ${\text{Al}}_{\text{2}}{\text{O}}_{\text{3,}}$ on the surface.) (c) Sodium and potassium lie above copper in the activity series. Explain why ${\text{Cu}}^{\text{2+}}$ ions in a ${\text{CuSO}}_{\text{4}}$ solution are not converted to metallic copper upon the addition of these metals, (d) A metal M reacts slowly with steam. There is no visible change when it is placed in a pale green iron(II) sulfate solution. Where should we place M in the activity series? (e) Before aluminum metal was obtained by electrolysis, it was produced by reducing its chloride $\left({\text{AlCl}}_{\text{3}}\right)$ with an active metal. What metals would you use to produce aluminum in that way?