Sunday, July 14, 2013

2SBS #9-22 p.151

9. Due to the fact that active metals are more reactive than less active metals, active metals tend to combine with other elements, forming compounds. On the other hand, less active metals usually remain separate. 

10. Since silver has a great lack of reactivity, it would be easiest to process.

11. Most metals exist in nature as minerals rather than as pure metallic elements because since most metals are more reactive than metals such as silver, gold and platinum, they tend to combine with other elements, forming compounds or minerals. 

12. A calcium metal with chromium (III) chloride reaction would be more likely to occur because calcium metal is more reactive than chromium metal, therefore forming a more likely reaction. 

13. Putting the metal zinc into the silver solution would more likely cause a reaction. 

14. A. It would be a poor idea to stir a solution of lead (II) nitrate with an iron spoon because it might cause a reaction. 
      B. Pb^2+(aq) + Fe(s) ---> Pb(s) + Fe^2+(aq)

15. Oxidation is when an ion or other species can be considered to lose one or more electrons. Reduction is a chemical change in which a reactant can be considered to gain one or more electrons. 

16. A. Au^3+ + 3e^- ---> Au
      B. V ---> V^4+ + 4e^-
      C. Cu+ ---> Cu^2+ + 1e^-

17. A. Reduction
      B. Oxidation
      C. Reduction

18. A. Zn^2 + has been oxidized. 
      B. Ni has been reduced. 
      C. Zn.

19. A. K+ has been oxidized. 
      B. Hg has been reduced.
      C. Hg^2+.

20. A. Al + Cr^3+ ---> Al^3+ + Cr
      B. Mn^2+ + Mg ---> Mn + Mg^2+

21. A. Electrometallurgy is the use of an electrical current to supply electrons to metal ions, this reducing them. 
      B. Pyrometallurgy is the treatment of metals and their ores with heat (thermal energy), as in a blast furnace. Carbon (coke) and carbon monoxide are common reducing agents, for they provide electrons, thus reducing the metal ions. 
      C. Hydrometallurgy is the treatment of ores and other metal-containing materials with reactants in water solution. It is used to recover silver and gold from old mine tailings by a process known as leaching. 

22. A. Electrometallurgy.
      B. Pyrometallurgy. 

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