2SBS #9-22, p. 151-152

9) Why are active metals more difficult to process and refine than are less active metals?

Active metals are more reactive than less active metals. Because of this, more active metals are more likely to combine and form compounds with other elements, where as less active metals tend to remain separate.

10) Based on your results from Investigating Matter B.5 (page 142), which metals involved in that investigation would be the easiest to process? Why?

Silver would have been the easiest to process because of its lack of reactivity. Since silver remains separate from other metals and elements, it would be quite easy to process.

11) Why do most metals exist in nature as minerals rather than as pure metallic elements?

Since most metals are more reactive than metals like silver, gold, and platinum, their reactivities tend to make them combine with other elements and form compounds, or minerals.

12) Which of these reactions is more likely to occur? Why? Refer to Table 2.5, page 145.)
a. calcium metal with chromium(III) chloride
b. chromium metal with calcium chloride

a. A reaction between calcium metal with chromium(III) chloride would more likely occur. Calcium metal is more reactive than chromium metal; therefore, putting calcium metal in chromium chloride would create a reaction, where as putting chromium metal in calcium chloride would not form any reaction.

13) Consider the following two equations. Which equation represents a reaction that is more likely to occur? Why?
a. Zn^2+(aq) + 2 Ag(s) ---> Zn(s) + 2 Ag^+(aq)
b. 2 Ag^+(aq) + Zn(s) ---> 2 Ag (s) + Zn^2+(aq)

b. Since zinc is much more reactive than silver, which is barely reactive, putting the metal zinc into a silver solution would cause a reaction; a reaction occurs between a more reactive metal and a less reactive solution.

14)
a. Why would it be a poor idea to stir a solution of lead(II) nitrate with an iron spoon? (Refer to Table 2.5, page 145.)
b. Write a chemical equation to support your answer.

a. Since iron is more reactive than lead, stirring a solution of lead (II) nitrate with an iron spoon would cause a reaction, and the iron spoon would most likely begin to dissolve.
b. Pb^2+(aq) + Fe(s) ---> Pb(s) + Fe^2+(aq)

15) Define oxidation and reduction in terms of electron transfer.

Oxidation is the apparent loss of one or more electrons that causes a metal to become a cation/aqueous solution. Reduction is the apparent gain of one or more electrons that causes a cation/aqueous solution to balance its electrical charge and become a metal.

16) Write an equation for each of the following processes:
a. the reduction of gold(III) ions to gold metal
b. the oxidation of elemental vanadium to vanadium(IV) ions
c. the oxidation of Cu+ to Cu^2+ ions

a. Au^3+ + 3e^- ---> Au
b. V ---> V^4+ + 4e^-
c. Cu+ ---> Cu^2+ + 1e^-

17) Identify each of the following equations as representing either an oxidation reaction or a reduction reaction:
a. Fe^2+ + 2e^- ---> Fe
b. Cr ---> Cr^3+ + 3e^-
c. Al^3+ + 3e^- ---> Al

a. reduction.
b. oxidation.
c. reduction.

18) Consider the following equation:
Zn(s) + Ni^2+(aq) ---> Zn^2+(aq) + Ni(s)
a. Which reactant has been oxidized? Explain your choice.
b. Which reactant has been reduced? Explain your choice.
c. What is the reducing agent in this reaction?

a. Zn^2+ has been oxidized. Zn loses two electrons to become a cation/aqueous solution, Zn^2+.
b. Ni has been reduced. Ni^2+ gains two electrons to essentially rebalance its charge and become a metal/solid as Ni.
c. The reducing agent in this reaction is Zn.

19) Consider the following equation:
2 K(s) + Hg^2+(aq) ---> 2 K^+(aq) + Hg(s)
a. Which reactant has been oxidized? Explain your choice.
b. Which reactant has been reduced? Explain your choice.
c. What is the oxidizing agent in this reaction?

a. K^+ has been oxidized. K loses an electron to become a cation/aqueous solution, K^+.
b. Hg has been reduced. Hg^2+ gains two electrons to essentially rebalance its charge and become a metal/solid as Hg.
c. The oxidizing agent in this reaction is Hg^2+.

20) Write an equation for
a. the oxidation of Al metal by Cr^3+ ions.
b. the reduction of Mn^2+ ions by Mg metal.

a. Al + Cr^3+ ---> Al^3+ + Cr
b. Mn^2+ + Mg ---> Mn + Mg^2+

21) Explain how each of the following processes converts metal cations to metal atoms:
a. electrometallurgy
b. pyrometallurgy
c. hydrometallurgy

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) What processes would be the most useful in obtaining the following elements from their ores?
a. Magnesium.
b. Lead.

a. Electrometallurgy.
b. Pyrometallurgy or find the metal uncombined.