Metallurgy 1 Which one of the following elements is most likely to be found as the free metal in nature A B C D E 2 Ca Au Al Fe Zn Which of the following oxides would be most useful as an additive to remove SiO2 by an acid base reaction in pyrometallurgy A B C D E 3 V2O5 Mn2O7 CrO3 Fe2O3 CaO Which one of the following elements uses hydrometallurgy as an important part in its processing A B C D E 4 ore Pb Cr Fe Si Al The following chemical reactions occur in a blast furnace during the refining of iron 1 2C s O2 g 2CO g heat 2 heat C s H2O g CO g H2 g 3 Fe3O4 s 4CO g 3Fe l 4CO2 g 4 Fe3O4 s 4H2 g 3Fe l 4H2O g Which reaction is responsible for cooling the furnace A Reaction 1 B Reaction 2 C Reaction 3 D Reaction 4 E Reactions 3 and 4 5 The hydrometallurgical process used in refining gold ore entails converting metallic gold to a water soluble complex The formula of the complex is A B C D E 6 Processes used to reduce metal ores or to refine metals that are based on the process of electrolysis are collectively referred to as A B C D E 7 pyrometallurgy hydrometallurgy electrometallurgy calcination roasting One of the ores containing copper is known as chalcocite What is the oxidation state of copper in Cu2S A B C D E 8 Au NH3 2 Au NH3 4 Au CN 2 Au CO 42 Au CO 4 0 1 2 3 4 The respective standard oxidation potentials for Cu Cu2 Ni Ni2 and Ag Ag are in V 0 34 0 28 and 0 80 Impure copper slabs at the anode are refined electrochemically affording much purer metallic copper at the cathode Which statement below is true A Cu is oxidized preferentially over both Ni and Ag so both Ni and Ag metals are separated as sludges below the anode B Ni is oxidized preferentially over Cu and Ni2 is reduced much less readily than Cu2 so Ni is separated as Ni2 in the electrolyte solution C Ag is oxidized preferentially over Cu and Ag is reduced much less readily than Cu2 so Ag is separated as Ag in the electrolyte solution D Ag is oxidized preferentially over Cu and Ag is reduced much more readily than Cu2 so Ag plates out with Cu at the cathode and cannot readily be removed from impure copper E Both Ni and Ag are oxidized preferentially over Cu and Ni2 and Ag is reduced much less readily than Cu2 so Ni and Ag are separated as Ni2 and Ag in the electrolyte solution 9 The following aqueous reaction is used as a first step in the process of recovering copper from copper containing ore CuFeS2 s 2CuFeS2 s 2H aq SO42 aq 4O2 g 2Cu2 aq 2SO42 aq Fe2O3 s 3S s H2O What is oxidized in this reaction A B C D E CuFeS2 s H aq SO42 aq O2 g Nothing is oxidized in this reaction 10 Which metals can only be made in pure form via electrolysis I Group I metal II Group II metals III transition metals A B C D E I only II only III only I and II I and III 11 Hydrometallurgy involves leaching a metal from an ore by selectively dissolving it then obtaining the free metal by reduction One such example is Au which can be leached from an ore with cyanide to form a soluble Au CN 2 complex The standard reduction potential E for Au CN 2 is 0 6 V and corresponds to the reaction below Au CN 2 e Au 2 CN E 0 6 V Which of the following metals could be used to reduce Au CN 2 to Au metal i ii iii A B C D E Pd Mg Fe i only ii only iii only i and ii ii and iii E 0 9 V E 2 4 V E 0 4 V for for for Pd2 2 e Pd Mg2 2 e Mg Fe2 2 e Fe 12 When hydrogen gas is used to reduce an ore as in a blast furnace it is converted to A ammonia B helium C hydrogen peroxide D water E hydroxide