Chapter 21 – Metallurgy and the Chemistry of Metals
33. The valence electron configuration for the alkaline earth metals is represented by which of
the following (n = outermost shell)?
34. The mineral cryolite, Na3AlF6, is used in the Hall process for aluminum production as
Chapter 21 – Metallurgy and the Chemistry of Metals
35. The Hall process involves the reduction of Al2O3 to aluminum by
36. Aluminum is an active metal, but does not corrode as iron does because
Chapter 21 – Metallurgy and the Chemistry of Metals
37. Which of these statements does not describe a property of aluminum?
38. Which of the following is not a true comparison of aluminum to copper?
Chapter 21 – Metallurgy and the Chemistry of Metals
39. Aluminum hydroxide, Al(OH)3, is
40.
What is the total number of moles (n) of electrons exchanged between the oxidizing agent and the reducing agent in the
reaction below to obtain vanadium metal?
V2O5(s) + 5Ca(l) → 2V(l) + 5CaO(s)
Chapter 21 – Metallurgy and the Chemistry of Metals
41.
What is the total number of moles (n) of electrons exchanged between the oxidizing agent and the reducing agent in the
reaction below to obtain chromium metal?
Cr2O3(s) + 2Al(s) → 2Cr(l) + Al2O3(s)
42. For the reaction 3Fe(s) + C(s) → Fe3C(s), H = 21 kJ/mol and S = 20.4 J/mol·K at
25C. Estimate the minimum temperature above which the formation of cementite (Fe3C) is
favored.
Chapter 21 – Metallurgy and the Chemistry of Metals
43.
How much energy (kJ) is released if 10.0g of Al(s) is reacted with excess Fe2O3(s) in the thermite reaction?
2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(l) H
= – 822.8 kJ/mol
44.
How much energy (kJ) is released when 15.0g of Fe(l) is produced in the thermite reaction?
2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(l) H
= – 822.8 kJ/mol
Chapter 21 – Metallurgy and the Chemistry of Metals
45.
The equilibrium 3Fe(s) + C(s) → Fe3C(s) is established in a solid solution. For such a solution, one can write an equilibrium
constant expression in the usual way except that the concentrations that refer to solids in the solid solution are included.
Determine the equilibrium constant for the formation of cementite from iron and carbon at 680C. (Given: for this reaction at
25C, H = 21 kJ/mol and S = 20.4 J/molK)
46. Write the chemical formula of epsomite (sold in pharmacies as Epsom salts).
Chapter 21 – Metallurgy and the Chemistry of Metals
47. Write the chemical formula of dolomite that provides a source for both magnesium and
calcium.
48. Write the chemical formula of corundum.
Chapter 21 – Metallurgy and the Chemistry of Metals
49. Write the chemical formula of pyrite.
50. Select True or False: The chemical formula of magnetite can be expressed as either
Fe3O4 or FeO Fe2O3
51.
Select True or False: The following equation correctly represents the balanced chemical equation illustrating the thermite
reaction.
2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(l)
Chapter 21 – Metallurgy and the Chemistry of Metals
52. Write a balanced chemical equation illustrating the decomposition of chile saltpeter to
form sodium nitrite and oxygen gas.
Chapter 21 – Metallurgy and the Chemistry of Metals
53.
Select True or False: The following depicts a correctly balanced chemical equation illustrating roasting.
2ZnS + 3O2 → 2ZnO + 2SO2
54. Select True or False: Cryolite, Na3AlF6, is mixed with alumina prior to electrolysis in the
production of Al because it acts a solute.
55.
Select True or False: The following two reactions represent the chemical reactions that can take place when magnesium is
burned in air.
2Mg(s) + O2(g) → 2MgO(s) and 3Mg(s) + N2(g) → Mg3N2(s)
Chapter 21 – Metallurgy and the Chemistry of Metals
56.
The following reaction is used to produce titanium metal at high temperature.
TiCl4(g) + 2Mg(l) → Ti(s) + 2MgCl2(l)
Which element is oxidized and which is reduced?
57.
The following reaction is used to produce chromium metal at high temperature.
Cr2O3(s) + 2Al(s) → 2Cr(l) + Al2O3(s)
Which element is oxidized and which is reduced?
Chapter 21 – Metallurgy and the Chemistry of Metals
58.
Select True or False: Potassium superoxide, KO2(s), is used in the breathing systems of biohazard suits. The following
separate chemical equations show how KO2(s) reacts with moisture and carbon dioxide in exhaled air to generate oxygen gas.
2KO2(s) + 2H2O(l) → 2KOH(aq) + O2(g) + H2O2(aq)
4KO2(s) + 2CO2(g) → 2K2CO3(s) + 3O2(g)
59. Select True or False: Three means used to concentrate ores are flotation, ferromagnetic
60. Select True or False: Mercury, magnesium, and zinc have low enough boiling points that
they can be purified by distillation.
Chapter 21 – Metallurgy and the Chemistry of Metals
61. Select True or False: Cast iron as it is prepared in a blast furnace is a product of high
purity.
62. Select True or False: Beryllium, the first element in Group 2A, is the most metallic
element in the group.
63.
Select True or False: Bauxite (Al2O32H2O) ore is the principal commercial source of aluminum metal.