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Chemistry for Engineering Students 4th Edition Brown Solutions Manual
Contents Chapter 1 Introduction to Chemistry ............................................................................................................... 1 Chapter 2 Atoms and Molecules .................................................................................................................... 20 Chapter 3 Molecules, Moles, and Chemical Equations ................................................................................. 39 Chapter 4 Stoichiometry ................................................................................................................................ 71 Chapter 5 Gases ........................................................................................................................................... 106 Chapter 6 The Periodic Table and Atomic Structure .................................................................................. 142 Chapter 7 Chemical Bonding and Molecular Structure .............................................................................. 169 Chapter 8 Molecules and Materials ............................................................................................................. 195 Chapter 9 Energy and Chemistry ................................................................................................................. 219 Chapter 10 Entropy and the Second Law of Thermodynamics ...................................................................... 248 Chapter 11 Chemical Kinetics ....................................................................................................................... 283 Chapter 12 Chemical Equilibrium ................................................................................................................. 321 Chapter 13 Electrochemistry ......................................................................................................................... 365 1 / 4
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Chapter 14 Nuclear Chemistry ...................................................................................................................... 396
Chapter 1 Introduction to Chemistry Critical Materials 1.1 Are the elements designated as critical materials all rare?Explain your answer.
They are not all necessarily rare, but many are found in only a few locations around the world and as such are subject to supply disruptions.
1.2 In what country is most of the world’s cobalt mined? What events in that country dramatically affected the price of cobalt?
The Democratic Republic of Congo produces most of the world’s cobalt. Political unrest in that country once caused a 600% spike in the price of cobalt. Political instability continues as well as issues with forced child labor in the mining of cobalt.
1.3 In what types of technology do the elements designated as critical materials generally play important roles?
They are important in light emission, magnetism, and a variety of applications associated with clean energy and electronics.
1.4 Based on the information in Figure 1.1, which three elements would you argue are the most critical among the “critical materials”? Justify your answer.
Neodymium, dysprosium, and terbium. Neodymium and dysprosium have the highest ranking in importance for clean energy. Dysprosium and terbium are ranked highest in terms of potential supply risk.
1.5 In what region of the periodic table are most of the elements that are listed as critical materials found?
Most of the critical elements are located in the middle of the periodic table, specifically the region known as the lanthanide series and to a lesser extent the transition elements.
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1.6 What agency of the U.S. government is responsible for identifying an element as a critical material? What sorts of applications are the primary concern of this agency?
The Department of Energy (DOE) and an organization that it manages called the Critical Materials Institute. Primary concerns are energy-related technologies, especially clean energy applications such as wind and solar energy and electric cars. 3 / 4
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The Study of Chemistry 1.7 When making observations in the laboratory, which perspective of chemistry are we normally using?
We make observations in the laboratory using the macroscopic perspective of chemistry, unless very sophisticated instruments are used.
1.8 Which of the following items are matter and which are not? (a) a flashlight, (b) sunlight, (c) an echo, (d) air at sea level, (e) air at the top of Mount Everest
(a) matter, (b) not matter, (c) not matter, (d) matter, (e) matter
1.9 Which macroscopic characteristics differentiate solids, liquids, and gases? (List as many as possible.)
Solids maintain a definite shape; liquids and gases do not. Gases expand to completely occupy their container; liquids assume the shape of the container but do not fully occupy it.Solids tend to have high densities, liquids usually slightly lower, and gases typically have very low densities, comparatively.
1.10 Do the terms element and atom mean the same thing? If not how do they differ?
No. An element is a pure substance, but the naturally occurring form of the element may contain more than one atom. An example of this is elemental nitrogen (N2). In this case the element has two atoms.
1.11 Label each of the following as either a physical process or a chemical process: (a) rusting of an iron bridge, (b) melting of ice, (c) burning of a wooden stick, (d) digestion of a baked potato, (e) dissolving of sugar in water.
A chemical change involves a change in the composition of matter; that is, some new substances are formed. A physical change only involves a change in the physical state of matter; no new substances are formed.
(a) rusting of an iron bridge Chemical, rust forms when iron and oxygen react chemically.(b) melting of ice Physical, change from the solid to the liquid state.(c) burning of a wooden stick Chemical, the molecules in the wood are changed into carbon dioxide and water during combustion.(d) digestion of a baked potato Chemical, larger food molecules are changed into smaller ones and eventually oxidized (“burned”) to produce energy.(e) dissolving of sugar in water Physical, the sugar molecules are not changed they just become surrounded by water molecules in solution.
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