9-22 p. 151

9. Active metals are more difficult to process and refine than are less active metals because they react with more minerals than non-reactive metals, and they require more energy.

10. Copper and Silver

11. Metals exist in nature as minerals rather than as pure metallic elements because they are unstable and combine with elements

12. a. Calcium is more reactive than chromium.

13. b. In the second equation, the atoms and charges are balanced.

14. a. It would be a bad idea to do that because iron is more reactive than lead nitrate, and a reaction would occur. The iron would dissolve the lead.
     b. Fe³ + Pb² --à Fe² + Pb³ 

15. Oxidation is any process in which one or more electrons cane considered as lost by a chemical species. Reduction is any process in which one or more electrons can be considered as gained by a chemical species.

16. a. Au³⁺ + 3e --à Au

      Gold ion       gold metal

     b. V--à V⁺ + 1e^-

 elemental vanadium   vanadium ions

    c. Cu --à Cu²⁺ + 2e^- 

17. a. Reduction

      b. Oxidation

      c. Reduction

18. a. Zinc because it has lost two electrons

      b. Nickel because it gained two electrons

      c. Zinc is the reducing agent.

19. a. Potassium because it lost 1 electron.

      b. Mercury because gained two electrons

      c. Potassium is the oxidizing agent.

20. a. Al + Cr³ -à Al^3- + Cr

      b. Mn²⁺  Mg --à Mg^2- 

21. Electrometallurgy: the use of electrical energy to add electrons to metal ions, thus reducing them.

     Pyrometallurgy: the use of high temperatures (thermal energy) to process metals or their ores.

     Hydrometallurgy: the industrial extraction of metals from ores at ordinary temperatures by water-     based process.

22. a. Magnesium: elctrometallurgy

      b. Lead: pyrometallurgy