A Molecular Approach, 4e - Notes for Chapter (24).doc

Chapter 24. Metals and Metallurgy Chapter 24. Metals and Metallurgy Chapter 24. Metals and Metallurgy Student Objectives 24.1 Vanadium: A Problem and an Opportunity Know that petroleum contains vanadium compounds as contaminants at levels that suggest they were part of some extinct species’ biological systems. Define metallurgy. 24.2 The General Properties and Natural Distribution of Metals Know the common physical properties of metals. Know that metals make up only about 25% of the Earth’s crust, but Earth’s core is thought to be all iron and nickel. Know that minerals are homogeneous, naturally-occurring, and crystalline inorganic solids. Know that an ore is a rock that contains a high concentration of a specific mineral. 24.3 Metallurgical Processes Know that extractive metallurgy involves separating the metal-containing components from the nonmetal-containing components. Define and describe the main forms of pyrometallurgy: calcination, roasting, and smelting. Define and describe the process of hydrometallurgy. Define and describe the process of electrometallurgy. Define and describe the process of powder metallurgy. 24.4 Metal Structures and Alloys Recall that structures of metals can be described as the closest packing of spheres into crystal types: face-centered cubic, body-centered cubic, and hexagonal closest packed. Define alloy, substitutional alloy, and interstitial alloy. Determine alloy composition from a binary phase diagram. Describe interstitial alloys in terms of octahedral holes and tetrahedral holes. 24.5 Sources, Properties, and Products of Some of the 3d Transition Metals Describe some general characteristics of titanium Describe some properties and reactions of chromium. Describe some properties and reactions of manganese. Describe some characteristics of cobalt. Describe some characteristics of copper. Describe some properties of nickel. Describe some properties of zinc. Section Summaries Lecture Outline Terms, Concepts, Relationships, Skills Figures, Tables, and Solved Examples Teaching Tips Suggestions and Examples Misconceptions and Pitfalls Lecture Outline Terms, Concepts, Relationships, Skills Figures, Tables, and Solved Examples 24.1 Vanadium: A Problem and an Opportunity Petroleum contaminants vanadium compounds ancient organism biology based on vanadium Metallurgy Intro figure: illustration of a fossil unnumbered figure: photo of vanadium 24.2 The General Properties and Natural Distribution of Metals Properties opaque thermal and electrical conductors malleable ductile Distribution elemental form: Ni, Cu, Pd, Ag, Pt, Au minerals and ores chloride minerals oxide minerals sulfide minerals Table 24.1 Thermal Conductivity and Electrical Resistivity of Several Metals unnumbered figure: photo of gold unnumbered figure: photo of NaCl basins 24.3 Metallurgical Processes Isolation steps mining separation refining Extractive metallurgy Pyrometallurgy calcination roasting smelting flux slag hydrometallurgy leaching electrometallurgy aluminum: Hall process copper powder metallurgy Figure 24.1 Separation by Air Figure 24.2 Separation by Using a Solution Figure 24.3 The Hall Process Figure 24.4 Copper Electrolysis Cell unnumbered figure: photo of machined metal products Teaching Tips Suggestions and Examples Misconceptions and Pitfalls 24.1 Vanadium: A Problem and an Opportunity The vanadium story is an interesting one since it requires some higher-order thinking skills. One might ask, “What else is in oil, and how did it get there?” The same question also is valid for coal. For example, uranium in coal occurs at levels between 1 and 10 ppm, and mercury in coal occurs at levels between 70 and 200 ppb. These may seem small unless one realizes that a large power plant under full load may burn 10,000 tons of coal per day. Vanadium may only be present in trace quantities, but the process of converting petroleum to fuel products or burning the fuels may concentrate the samples. 24.2 The General Properties and Natural Distribution of Metals Understanding the distribution of metals in nature requires knowledge of the structure and composition of ores and minerals. Most metallurgy has to deal with huge quantities of ores to generate a limited amount of metal, making cost effectiveness a challenge. For many metals, recycling is appropriate. This is especially true for aluminum and copper that use expensive electricity in electrolysis. 24.3 Metallurgical Processes Metallurgical processes have been developed over time to make the isolation of metals more efficient. The technique used for a particular metal is likely to depend on the nature and quantity of an elemental metal or its ore. Gold occurs as a metal but in small enough particles that leaching it is justified, in part, because of its great value. The reduction of iron in an ore is accomplished by a redox reaction in which carbon is burned with the ore, forming iron metal and carbon dioxide. On the other hand, the oxidation potential of carbon is not sufficient to effect the same transformation in aluminum. Reduction of Al3+ requires the more costly electrolysis. Metallurgy takes advantage of basic chemical principles to concentrate an element or mineral or to reduce metal cations to the elemental form. Lecture Outline Terms, Concepts, Relationships, Skills Figures, Tables, and Solved Examples 24.4 Metal Structures and Alloys Closest packing of spheres face-centered cubic body-centered cubic hexagonal closest packed Alloys substitutional miscible solid solutions alloys with limited solubility phase diagrams and examples interstitial octahedral holes tetrahedral holes Table 24.2 The Crystal Structures of the 3d Elements unnumbered figure: illustrations of copper, nickel-copper-alloy crystal structures Figure 24.5 Cu-Ni Phase Diagram Examples 24.1 and 24.2 Determining Alloy Compositions from a Phase Diagram Figure 24.6 Cr-V Phase Diagram Figure 24.7 Cr-Ni Phase Diagram Examples 24.3 and 24.4 Alloy Compositions in a Solid Solution with Limited Solubility Figure 24.8 Octahedral Holes in Closest Packed Crystals Figure 24.9 A Different View of an Octahedral Hole Figure 24.10 A Tetrahedral Hole in a Closest Packed Crystal Table 24.3 Formulas of Several Interstitial Alloys 24.5 Sources, Properties, and Products of Some of the 3d Transition Metals Titanium sources (ores, minerals); uses; reactions Chromium sources (ores, minerals); uses; alloys; reactions Manganese sources (ores, minerals); uses; alloys; reactions Cobalt sources (ores, minerals); uses (magnetic materials) Copper sources (elemental form, ores, minerals); uses; alloys (brass) Nickel sources; uses; alloys Zinc sources (ores, minerals); uses; alloys Figure 24.11 Chromium Compounds Table 24.4 The Colors of Various Chromium Compounds unnumbered figure: ball-and-stick models of chromate and dichromate unnumbered figure: combustion of ammonium dichromate unnumbered figure: photo of copper wiring unnumbered figure: photos of uses of copper unnumbered figure: photo of zinc phosphate on steel Teaching Tips Suggestions and Examples Misconceptions and Pitfalls 24.4 Metal Structures and Alloys Knowledge of crystal lattices takes on a practical application at this stage. Understanding substitutional alloys requires knowledge of the size of a potential component and melting information as a function of the mole percent of the components. Interstitial alloys can take advantage of the holes in closest packed crystals, both octahedral and tetrahedral holes that are determined by the number of neighboring atoms. Conceptual Connection 24.1 Interstitial Alloys Ask the students to answer to same question from Conceptual Connection 24.1 for the case of octahedral holes. What fraction of octahedral holes would need to be filled to get the same ratio of metals as was obtained for the tetrahedral holes? The formulation of alloys takes advantage of knowledge of both the microscopic properties (crystal forms, sizes of component metals) and macroscopic properties (melting points and phase diagrams). 24.5 Sources, Properties, and Products of Some of the 3d Transition Metals Case studies of seven metals are outlined. They compare and contrast sources, method of metal isolation, and practical applications or uses of the metal and some of its compounds. Important and interesting examples have been selected in preference to marching through all the groups. 322 Copyright © 2017 by Education, Inc. 323 Copyright © 2017 by Education, Inc.