Deck 21: Metallurgy and the Chemistry of Metals

Question 1

A naturally occurring substance with a range of chemical composition is

A) an element.
B) a mineral.
C) gangue.
D) an ore.
E) an amalgam.

Answer 1

a mineral.

Question 2

According to the band theory, a band is

A) an elastic force that holds electrons close to atoms in an insulator.
B) the energy gap associated with semiconductors.
C) a large number of molecular orbitals that are close together in energy.
D) a large number of atoms in a crystal.

Answer 2

a large number of molecular orbitals that are close together in energy.

Question 3

According to the band theory, which of these statements provide(s) an explanation for the high electrical conductivity of metals
I. a partly filled conduction band
II. a valence band overlapping an empty conduction band
III. a filled valence band
IV. a large gap between the valence band and the conduction band

A) I and II
B) I and III
C) III
D) III and IV
E) IV

Answer 3

I and II

Question 4

Metallic sodium is obtained commercially from molten sodium chloride by

A) chemical reduction with magnesium.
B) flotation.
C) electrolysis.
D) zone refining.
E) roasting.

Question 5

In n-type semiconductors

A) the energy gap between the valence band and the conduction band is very large.
B) impurities that donate electrons are added to provide conduction electrons.
C) a valence band overlaps the empty conduction band.
D) impurities that provide "positive holes" are added to a pure semiconductor.

Question 6

Volatile impurities are removed from ores by means of

A) roasting.
B) amalgamation.
C) electrolysis.
D) flotation.
E) zone refining.

Question 7

Alloys of iron that contain 1.0-1.5% carbon and some manganese, phosphorus, silicon, and sulfur are called

A) steel.
B) cast iron.
C) coke.
D) pig iron.
E) hematite.

Question 8

In p-type semiconductors,

A) the semiconductors are "ultra purified" to increase conductivity.
B) the valence and conduction bands are formed exclusively from "p orbitals."
C) the semiconductors are "patented" for use in commercial applications.
D) acceptor impurities are added to provide "positive holes" that increase the electrical conductivity of the semiconductor.

Question 9

Which one of these metals would normally be obtained by chemical reduction

A) aluminum
B) calcium
C) lithium
D) sodium
E) vanadium

Question 10

Which of these reactions represents the removal of silica from iron ore in a blast furnace

A)SiO₂(s) $\rarr$ SiO₂(g)
B)SiO₂(s) + CaO(s) $\rarr$ CaSiO₃(l)
C)SiO₂(s) + 4HF(g) $\rarr$ SiF₄(g) + 2H₂O(g)
D)SiO₂(s) + C(s) $\rarr$ Si(l) + CO₂(g)
E)SiO₂(s) + CO(g) $\rarr$ SiCO₃(l)

Question 11

Which of the following diagrams represents a semiconductor

A) A
B) B
C) C

Question 12

In the Hall process, ____________ is reduced ____________.

A) nickel; electrolytically
B) aluminum; electrolytically
C) nickel; by reaction with metallic sodium
D) aluminum; by reaction with metallic sodium
E) copper; electrolytically

Question 13

In the Mond process, nickel is purified by

A) dissolving the crude ore in sulfuric acid, and precipitating the nickel(II) ion as the sulfate salt.
B) dissolving the crude ore in a lye (NaOH) solution, and precipitating the nickel(II) ion as the hydroxide salt.
C) heating the crude ore to its melting point and electrolytically reducing the nickel(II) ions to form the metal.
D) passing sodium gas over the crude ore at high temperatures, chemically reducing the nickel(II) to nickel metal.
E) passing carbon monoxide over the impure metal at high temperature, forming the volatile Ni(CO)₄ which is removed as a gas.

Question 14

Which one of these metals would normally be obtained by electrolytic reduction

A) aluminum
B) chromium
C) copper
D) iron
E) zinc

Question 15

Which of these elements when doped into silicon would give an n-type semiconductor

A) C
B) Ga
C) P
D) Ge
E) B

Question 16

The principal reducing agent in a blast furnace is

A) CaO(s)
B) CaSiO₃(l)
C) CO(g)
D) O₂(g)
E) CO₂(g)

Question 17

The flotation process used in metallurgy involves

A) the roasting of sulfides.
B) separation of gangue from ore.
C) electrolytic reduction.
D) chemical reduction of a metal.
E) zone refining.

Question 18

Which one of these elements would give a p-type semiconductor when added to a silicon crystal

A) C
B) P
C) As
D) Ga
E) Sb

Question 19

The naturally occurring form of a metal that is concentrated enough to allow economical recovery of the metal is known as

A) an element.
B) a mineral.
C) gangue.
D) an ore.
E) an amalgam.

Question 20

What effect does increasing temperature have on the conductivities of semiconductors

A) increases
B) decreases
C) no change
D) cannot be predicted

Question 21

Barite, anglesite, and epsomite are all examples of what type of mineral

A) carbonates
B) oxides
C) sulfides
D) sulfates
E) silicates

Question 22

The mineral cryolite, Na₃AlF₆, is used in the Hall process for aluminum production as

A) the source of aluminum (the ore).
B) a chemical reducing agent.
C) a material that forms a slag and thus removes impurities.
D) a solvent for alumina, Al₂O₃.

Question 23

Which of the following is not a true comparison of aluminum to copper

A) Aluminum is cheaper than copper.
B) Aluminum is lighter than copper.
C) Aluminum is a better conductor of electricity than copper.
D) Aluminum is easier to oxidize than copper.

Question 24

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) $\rarr$ 2V(l) + 5CaO(s)

A) 1
B) 2
C) 5
D) 10
E) 0

Question 25

Calcium metal is produced by electrolysis of

A) CaSO₄.
B) CaF₂.
C) CaCO₃.
D) Ca(OH)₂.
E) CaCl₂.

Question 26

Basic properties are characteristic of all alkaline earth metal oxides except one. The formula of this exception is

A) BeO.
B) MgO.
C) SO₂.
D) B₂O₃.
E) CaO.

Question 27

Aluminum hydroxide, Al(OH)₃, is

A) an acid.
B) an amphoteric hydroxide.
C) a base.
D) an explosive hydroxide.
E) used to make amalgams.

Question 28

Which of the following diagrams represents an insulator

A) A
B) B
C) C

Question 29

Which two compounds are produced by the Solvay process

A) CaCO₃ and CaO
B) CaCO₃ and Na₂CO₃
C) NaHCO₃ and NaCl
D) NH₃ and NH₄Cl
E) NaHCO₃ and Na₂CO₃

Question 30

The alkali metals listed in order of increasing melting point is consistent with which of the following

A) Li < Na < K < Rb < Cs
B) Cs < Rb < K < Na < Li
C) Be < Mg < Ca < Sr < Ba
D) Ba < Sr < Ca < Mg < Be

Question 31

What are the two raw materials used in the Solvay process

A) NaHCO₃ and NaCl
B) CaCO₃ and Na₂CO₃
C) NaCl and NaCO₃
D) NH₃ and NaCl
E) Na₂CO₃ and NH₄Cl

Question 32

In the production of potassium metal, the source of electrons in the reduction of K⁺ ions is

A) H₂(g)
B) Na(g)
C) CO(g)
D) CaO(s)
E) electrolysis

Question 33

Which of these statements does not describe a property of aluminum?

A) Al is an efficient electrical conductor.
B) Al has a low density compared to other metals.
C) Al forms an amphoteric hydroxide.
D) Al is generally considered toxic to humans
E) Al has a great affinity for oxygen.

Question 34

Which one of these elements has seawater as its commercial source

A) Mg
B) Al
C) Ca
D) Sn
E) Cd

Question 35

Which of these ions is most likely to substitute for Ca²⁺ in the human body

A) Cl^-
B) Sr²⁺
C) K⁺
D) S^2-
E) Pb²⁺

Question 36

Aluminum is an active metal, but does not corrode as iron does because

A) Al does not react with O₂.
B) a protective layer of Al₂O₃ forms on the metal surface.
C) Al is harder to oxidize than is Fe.
D) the enthalpy of formation of aluminum oxide is negative.
E) aluminum has a high tensile strength.

Question 37

Argentite, chalcocite and cinnabar are all examples of what type of mineral

A) carbonates
B) oxides
C) halides
D) phosphates
E) sulfides

Question 38

The valence electron configuration for the alkaline earth metals is represented by which of the following (n = outermost shell)

A) ns¹
B) ns²
C) ns²np¹
D) ns² np²
E) ns² np³

Question 39

The Hall process involves the reduction of Al₂O₃ to aluminum by

A) carbon (coke).
B) carbon monoxide.
C) molecular hydrogen.
D) sodium.
E) electrolysis.

Question 40

Which group of elements includes the most reactive of all the metallic elements

A) alkali metals
B) alkaline earth metals
C) coinage metals (Group 1B)
D) transition metals
E) Group 2B metals

Question 41

The following equation correctly represents the balanced chemical equation illustrating the thermite reaction.2Al(s) + Fe₂O₃(s) $\rarr$ Al₂O₃(s) + 2Fe(l)

Question 42

The equilibrium 3Fe(s) + C(s) $\rarr$ 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 680 ^$\circ$ C. (Given: for this reaction at 25 ^$\circ$ C, $\Delta$ H ^$\circ$ = 21 kJ/mol and $\Delta$ S ^$\circ$ = 20.4 J/mol.K)

A) 0.75
B) 0.33
C) 3.1
D) 0.82
E) 1.2

Question 43

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) $\rarr$ 2KOH(aq) + O₂(g) + H₂O₂(aq)
4KO₂(s) + 2CO₂(g) $\rarr$ 2K₂CO₃(s) + 3O₂(g)

Question 44

Write the chemical formula of corundum.

A) Al₃O₂
B) Al₂O₃
C) AlO₃
D) Al₃O
E) None of the above

Question 45

The chemical formula of magnetite can be expressed as either
Fe₃O₄ or FeO $\times$ Fe₂O₃

Question 46

Write a balanced chemical equation illustrating the decomposition of chile saltpeter to form sodium nitrite and oxygen gas.

A)2NaNO₂(s) $\rarr$ 2NaNO₃(s) + O₂(g)
B)NaNO₃(s) $\rarr$ NaNO₂(s) + O₂(g)
C)2NaNO₃(s) $\rarr$ 2NaNO₂(s) + O₂(g)
D)3NaNO₂(s) $\rarr$ 3NaNO₃(s) + O₂(g)
E) None of the above

Question 47

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) $\rarr$ 2Cr(l) + Al₂O₃(s)

A) 1
B) 2
C) 3
D) 6
E) 21

Question 48

Write the chemical formula of dolomite that provides a source for both magnesium and calcium.

A)CaCO₃ $\times$ Mg(OH)₂
B)Ca(OH)₂ $\times$ MgCO₃
C)Ca(OH)₂ $\times$ Mg(OH)₂
D)CaCO₃ $\times$ MgCO₃
E) None of the above

Question 49

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) $\rarr$ Al₂O₃(s) + 2Fe(l) $\Delta$ H ^$\circ$ = - 822.8 kJ/mol

A) 8,230 kJ
B) 823 kJ
C) 305 kJ
D) 152 kJ
E) 4,110 kJ

Question 50

Write the chemical formula of epsomite (sold in pharmacies as Epsom salts).

A) CaSO₄ $\times$ 7H₂O
B) MgSO₄ $\times$ 7H₂O
C) Na₂SO₄ $\times$ 7H₂O
D) FeSO₄ $\times$ 7H₂O
E) None of the above

Question 51

For the reaction 3Fe(s) + C(s) $\rarr$ Fe₃C(s), $\Delta$ H ^$\circ$ = 21 kJ/mol and $\Delta$ S ^$\circ$ = 20.4 J/mol·K at 25 ^$\circ$ C. Estimate the minimum temperature above which the formation of cementite (Fe₃C) is favored.

A) 1.0 ^$\circ$ C
B) 970 ^$\circ$ C
C) 700 ^$\circ$ C
D) 1000 ^$\circ$ C
E) 760 ^$\circ$ C

Question 52

The following depicts a correctly balanced chemical equation illustrating roasting.2ZnS + 3O₂ $\rarr$ 2ZnO + 2SO₂

Question 53

Cryolite, Na₃AlF₆, is mixed with alumina prior to electrolysis in the production of Al because it acts a solute.

Question 54

How much energy (kJ) is released when 15.0g of Fe(l) is produced in the thermite reaction
2Al(s) + Fe₂O₃(s) $\rarr$ Al₂O₃(s) + 2Fe(l) $\Delta$ H ^$\circ$ = - 822.8 kJ/mol

A) 12,300 kJ
B) 221 kJ
C) 110. kJ
D) 6,170 kJ
E) 54.8 kJ

Question 55

Three means used to concentrate ores are flotation, ferromagnetic separation, and amalgamation.

Question 56

Write the chemical formula of pyrite.

A) FeS
B) Fe₂S₃
C) FeS₂
D) Fe₃S₂
E) None of the above

Question 57

The following reaction is used to produce titanium metal at high temperature.TiCl₄(g) + 2Mg(l) $\rarr$ Ti(s) + 2MgCl₂(l)
Which element is oxidized and which is reduced

A) Both titanium and magnesium are oxidized
B) Titanium is reduced, magnesium is oxidized
C) Magnesium is reduced, titanium is oxidized
D) Neither titanium or magnesium is oxidized
E) None of the above

Question 58

The following two reactions represent the chemical reactions that can take place when magnesium is burned in air.2Mg(s) + O₂(g) $\rarr$ 2MgO(s) and 3Mg(s) + N₂(g) $\rarr$ Mg₃N₂(s)

Question 59

Mercury, magnesium, and zinc have low enough boiling points that they can be purified by distillation.

Question 60

The following reaction is used to produce chromium metal at high temperature.Cr₂O₃(s) + 2Al(s) $\rarr$ 2Cr(l) + Al₂O₃(s)
Which element is oxidized and which is reduced

A) Both chromium and aluminum are oxidized
B) Chromium is oxidized and aluminum is reduced
C) Chromium is reduced and aluminum is oxidized
D) Neither chromium or aluminum are oxidized
E) None of the above

Question 61

Cast iron as it is prepared in a blast furnace is a product of high purity.

Question 62

Bauxite (Al₂O₃ $\times$ 2H₂O) ore is the principal commercial source of aluminum metal.

Question 63

Beryllium, the first element in Group 2A, is the most metallic element in the group.