Modul Kimia Lingkungan PT docx
PREFACE TO THE SECOND EDITION
Fundamentals of Environmental Chemistry , 2nd edition, is written with two major objectives in mind. The first of these is to provide a reader having little or no background in chemistry with the fundamentals of chemistry needed for a trade, profession, or curriculum of study that requires a basic knowledge of these topics. The second objective of the book is to provide a basic coverage of modern environ- mental chemistry. This is done within a framework of industrial ecology and an emerging approach to chemistry that has come to be known as “green chemistry.”
Virtually everyone needs some knowledge of chemistry. Unfortunately, this vital, interesting discipline “turns off” many of the very people who need a rudimentary knowledge of it. There are many reasons that this is so. For example, “chemophobia,” an unreasoned fear of insidious contamination of food, water, and air with chemicals at undetectable levels that may cause cancer and other maladies is widespread among the general population. The language of chemistry is often made too complex so that those who try to learn it retreat from concepts such as moles, orbitals, electronic configurations, chemical bonds, and molecular structure before coming to realize that these ideas are comprehensible and even interesting and useful.
Fundamentals of Environmental Chemistry is designed to be simple and understandable, and it is the author’s hope that readers will find it interesting and applicable to their own lives. Without being overly simplistic or misleading, it seeks to present chemical principles in ways that even a reader with a minimal background in, or no particular aptitude for, science and mathematics can master the material in it and apply it to a trade, profession, or course of study.
One of the ways in which Environmental Chemistry Fundamentals presents chemistry in a “reader-friendly” manner is through a somewhat unique organizational structure. In the first few pages of Chapter 1, the reader is presented with a “mini-course” in chemistry that consists of the most basic concepts and terms needed to really begin to understand chemistry. To study chemistry, it is necessary to know a few essential things—what an atom is, what is meant by elements, chemical formulas, chemical bonds, molecular mass. With these terms defined in very basic One of the ways in which Environmental Chemistry Fundamentals presents chemistry in a “reader-friendly” manner is through a somewhat unique organizational structure. In the first few pages of Chapter 1, the reader is presented with a “mini-course” in chemistry that consists of the most basic concepts and terms needed to really begin to understand chemistry. To study chemistry, it is necessary to know a few essential things—what an atom is, what is meant by elements, chemical formulas, chemical bonds, molecular mass. With these terms defined in very basic
Chapter 2 discusses matter largely on the basis of its physical nature and behavior, introducing physical and chemical properties, states of matter, the mole as
a quantity of matter, and other ideas required to visualize chemical substances as physical entities. Chapters 3–5 cover the core of chemical knowledge constructed as
a language in which elements and the atoms of which they are composed (Chapter 3) are presented as letters of an alphabet, the compounds made up of elements (Chapter
4) are analogous to words, the reactions by which compounds are synthesized and changed (Chapter 5) are like sentences in the chemical language, and the mathematical aspects hold it all together quantitatively. Chapters 6–8 constitute the remainder of material that is usually regarded as essential material in general chemistry. Chapter 9 presents a basic coverage of organic chemistry. Although this topic is often ignored at the beginning chemistry level, those who deal with the real world of environmental pollution, hazardous wastes, agricultural science, and other applied areas quickly realize that a rudimentary understanding of organic chemistry is essential. Chapter 10 covers biological chemistry, an area essential to understanding later material dealing with environmental and toxicological chemistry.
Beyond Chapter 10, the book concentrates on environmental chemistry. Traditionally, discussion of environmental science has been devoted to the four traditional spheres—the hydrosphere, atmosphere, geosphere, and biosphere—that is, water, air, land, and life. It has usually been the case that, when mentioned at all in environmental science courses, human and industrial activities have been presented in terms of pollution and detrimental effects on the environment. Fundamentals of Environmental Chemistry goes beyond this narrow focus and addresses a fifth sphere of the environment, the anthrosphere, consisting of the things that humans make, use, and do. In taking this approach, it is recognized that humans have vast effects upon the environment and that they will use the other environmental spheres and the materials, energy, and life forms in them for perceived human needs. The challenge before humankind is to integrate the anthrosphere into the total environment and to direct human efforts toward the preservation and enhancement of the environment, rather than simply its exploita- tion. Environmental chemistry has a fundamental role in this endeavor, and this book is designed to assist the reader with the basic tools required to use environmental chemistry to enhance the environment upon which we all ultimately depend for our existence and well-being.
Chapters 11–13 address the environmental chemistry of the hydrosphere. Chapter 11 discusses the fundamental properties of water, water supply and distri- bution, properties of bodies of water, and basic aquatic chemistry, including acid- base behavior, phase interactions, oxidation-reduction, chelation, and the important influences of bacteria, algae, and other life forms on aquatic chemistry. Chapter 12 deals specifically with water pollution and Chapter 13 with water treatment.
Chapter 14 introduces the atmosphere and atmospheric chemistry, including the key concept of photochemistry. It discusses stratification of the atmosphere, Earth’s crucial energy balance between incoming solar energy and outgoing infrared energy, and weather and climate as they are driven by redistribution of energy and water in Chapter 14 introduces the atmosphere and atmospheric chemistry, including the key concept of photochemistry. It discusses stratification of the atmosphere, Earth’s crucial energy balance between incoming solar energy and outgoing infrared energy, and weather and climate as they are driven by redistribution of energy and water in
The geosphere is addressed in Chapters 17 and 18. Chapter 17 is a discussion of the composition and characteristics of the geosphere. Chapter 18 deals with soil and agriculture and addresses topics such as conservation tillage and the promise and potential pitfalls of genetically modified crops and food.
Chapters 19–22 discuss anthrospheric aspects of environmental chemistry. Chapter 19 outlines industrial ecology as it relates to environmental chemistry. Chapter 20 covers the emerging area of “green chemistry,” defined as the sustainable exercise of chemical science and technology within the framework of good practice of industrial ecology so that the use and handling of hazardous substances are minimized and such substances are never released to the environment. Chapter 21 covers the nature, sources, and chemistry of hazardous substances. Chapter 22 addresses the reduction, treatment, and disposal of hazardous wastes within a framework of the practice of industrial ecology.
Aspects of the biosphere are covered in several parts of the book. Chapter 10 provides a basic understanding of biochemistry as it relates to environmental chemistry. The influence of organisms on the hydrosphere is discussed in Chapters 11–13. Chapter 23 deals specifically with toxicological chemistry.
Chapter 24 covers resources, both renewable and nonrenewable, as well as energy from fossil and renewable sources. The last two chapters outline analytical chemistry. Chapter 25 presents the major concepts and techniques of analytical chemistry. Chapter 26 discusses specific aspects of environmental chemical analysis, including water, air, and solid-waste analysis, as well as the analysis of xenobiotic species in biological systems.
The author welcomes comments and questions from readers. He can be reached by e-mail at manahans@missouri.edu.
Stanley E. Manahan is Professor of Chemistry at the University of Missouri- Columbia, where he has been on the faculty since 1965 and is President of ChemChar Research, Inc., a firm developing non-incinerative thermochemical waste treatment processes. He received his A.B. in chemistry from Emporia State University in 1960 and his Ph.D. in analytical chemistry from the University of Kansas in 1965. Since 1968 his primary research and professional activities have been in environmental chemistry, toxicological chemistry, and waste treatment. He teaches courses on environmental chemistry, hazardous wastes, toxicological chemistry, and analytical chemistry. He has lectured on these topics throughout the U.S. as an American Chemical Society Local Section tour speaker, in Puerto Rico, at Hokkaido University in Japan, and at the National Autonomous University in Mexico City. He was the recipient of the Year 2000 Award of the Environmental Chemistry Division of the Italian Chemical Society.
Professor Manahan is the author or coauthor of approximately 100 journal articles in environmental chemistry and related areas. In addition to Fundamentals of Environmental Chemistry , 2nd ed., he is the author of Environmental Chemistry, 7th
ed. (2000, Lewis Publishers), which has been published continuously in various editions since, 1972. Other books that he has written are Industrial Ecology: Environmental Chemistry and Hazardous Waste (Lewis Publishers, 1999), Environmental Science and Technology (Lewis Publishers, 1997), Toxicological Chemistry , 2nd ed. (Lewis Publishers, 1992), Hazardous Waste Chemistry, Toxicology and Treatment (Lewis Publishers, 1992), Quantitative Chemical Analysis, Brooks/Cole, 1986), and General Applied Chemistry, 2nd ed. (Willard Grant Press, 1982).
CONTENTS
CHAPTER 1 INTRODUCTION TO CHEMISTRY
1.1 Chemistry and Environmental Chemistry
1.2 A Mini-Course in Chemistry
1.3 The Building Blocks of Matter
1.4 Chemical Bonds and Compounds
1.5 Chemical Reactions and Equations
1.6 Numbers in Chemistry: Exponential notation
1.7 Significant Figures and Uncertainties in Numbers
1. 8 Measurement and Systems of Measurement
1.9 Units of Mass
1.10 Units of Length
1.11 Units of Volume
1.12 Temperature, Heat, and Energy
1.13 Pressure
1.14 Units and Their Use in Calculations Chapter Summary
CHAPTER 2 MATTER AND PROPERTIES OF MATTER
2.1 What is Matter?
2.2 Classification of Matter
2.3 Quantity of Matter: the Mole
2.4 Physical Properties of Matter
2.5 States of Matter
2.6 Gases
2.7 Liquids and Solutions
2.8 Solids
2.9 Thermal properties
2.10 Separation and Characterization of Matter Chapter Summary
CHAPTER 3 ATOMS AND ELEMENTS
3.1 Atoms and Elements
3.2 The Atomic Theory
3.3 Subatomic Particles
3.4 The Basic Structure of the Atom
3.5 Development of the Periodic Table
3.6 Hydrogen, the Simplest Atom
3.7 Helium, the First Atom With a Filled Electron Shell
3.8 Lithium, the First Atom With BothInner and Outer Electrons
3.9 The Second Period, Elements 4–10
3.10 Elements 11–20, and Beyond
3.11 A More Detailed Look at Atomic Structure
3.12 Quantum and Wave Mechanical Models of Electrons in Atoms
3.13 Energy Levels of Atomic Orbitals
3.14 Shapes of Atomic Orbitals
3.15 Electron Configuration
3.16 Electrons in the First 20 Elements
3.17 Electron Configurations and the Periodic Table Chapter Summary Table of Elements
CHAPTER 4 CHEMICAL BONDS, MOLECULES, AND COMPOUNDS
4.1 Chemical Bonds and Compound Formation
4.2 Chemical Bonding and the Octet Rule
4.3 Ionic Bonding
4.4 Fundamentals of Covalent Bonding
4.5 Covalent Bonds in Compounds
4.6 Some Other Aspects of Covalent Bonding
4.7 Chemical Formulas of Compounds
4.8 The Names of Chemical Compounds
4.9 Acids, Bases, and Salts Chapter Summary
CHAPTER 5 CHEMICAL REACTIONS, EQUATIONS, AND STOICHIOMETRY
5.1 The Sentences of Chemistry
5.2 The Information in a Chemical Equation
5.3 Balancing Chemical Equations
5.4 Will a Reaction Occur?
5.5 How Fast Does a Reaction Go?
5.6 Classification of Chemical Reactions
5.7 Quantitative Information from Chemical Reactions
5.8 What is Stoichiometry and Why is it Important? Chapter Summary
CHAPTER 6 ACIDS, BASES, AND SALTS
6.1 The Importance of Acids, Bases, and Salts
6.2 The Nature of Acids, Bases, and Salts
6.3 Conductance of Electricity by Acids, Bases, and Salts in Solution
6.4 Dissociation of Acids and Bases in Water
6.5 The Hydrogen Ion Concentration and Buffers
6.6 pH and the Relationship Between Hydrogen Ion and Hydroxide Ion Concentrations
6.7 Preparation of Acids
6.8 Preparation of Bases
6.9 Preparation of Salts
6.10 Acid Salts and Basic Salts
6.11 Names of Acids, Bases, and Salts Chapter Summary
CHAPTER 7 SOLUTIONS
7.1 What are Solutions? Why are they Important?
7.2 Solvents
7.3 Water—A Unique Solvent
7.4 The Solution Process and Solubility
7.5 Solution Concentrations
7.6 Standard Solutions and Titrations
7.7 Physical Properties of Solutions
7.8 Solution Equilibria
7.9 Colloidal Suspensions Chapter Summary
CHAPTER 8 CHEMISTRY AND ELECTRICITY
8.1 Chemistry and Electricity
8.2 Oxidation and Reduction
8.3 Oxidation-Reduction in Solution
8.4 The Dry Cell
8.5 Storage Batteries
8.6 Using Electricity to Make Chemical Reactions Occur
8.7 Electroplating
8.8 Fuel Cells
8.9 Solar Cells
8.10 Reaction Tendency
8.11 Effect of Concentration: Nernst Equation
8.12 Natural Water Purification Processes
8.13 Water Reuse and Recycling Chapter Summary
CHAPTER 9 ORGANIC CHEMISTRY
9.1 Organic Chemistry
9.2 Hydrocarbons
9.3 Organic Functional Groups and Classes of Organic Compounds
9.4 Synthetic Polymers Chapter Summary
CHAPTER 10 BIOLOGICAL CHEMISTRY
10.1 Biochemistry
10.2 Biochemistry and the Cell
10.7 Nucleic Acids
10.8 Recombinant DNA and Genetic Engineering
10.9 Metabolic Processes Chapter Summary
CHAPTER 11 ENVIRONMENTAL CHEMISTRY OF WATER
11.1 Introduction
11.2 The Properties of Water, a Unique Substance
11.3 Sources and Uses of Water: the Hydrologic Cycle
11.4 The Characteristics of Bodies of Water
11.5 Aquatic Chemistry
11.6 Nitrogen Oxides in the Atmosphere
11.7 Metal Ions and Calcium in Water
11.8 Oxidation-Reduction
11.9 Complexation and Chelation
11.10 Water Interactions with Other Phases
11.11 Aquatic Life
11.12 Bacteria
11.13 Microbially Mediated Elemental Transistions and Cycles Chapter Summary
CHAPTER 12 WATER POLLUTION
12.1 Nature and Types of Water Pollutants
12.2 Elemental Pollutants
12.3 Heavy Metal
12.4 Metalloid
12.5 Organically Bound Metals and Metalloids
12.6 Inorganic Species
12.7 Algal Nutrients and Eutrophications
12.8 Acidity, Alkalinity, and Salinity
12.9 Oxygen, Oxidants, and Reductants
12.10 Organic Pollutants
12.11 Pesticides in Water
12.12 Polychlorinated Biphenyls
12.13 Radionuclides in the Aquatic Environment Chapter Summary
CHAPTER 13 WATER TREATMENT
13.1 Water Treatment and Water Use
13.2 Municipal Water Treatment
13.3 Treatment of Water For Industrial Use
13.4 Sewage Treatment
13.5 Industrial Wastewater Treatment
13.6 Removal of Solids
13.7 Removal of Calcium and Other Metals
13.8 Removal of Dissolved Organics
13.9 Removal of Dissolved Inorganics
13.10 Sludge
13.11 Water Disinfection
13.12 Natural Water Purification Processes
13.13 Water Reuse and Recycling Chapter Summary
CHAPTER 14 THE ATMOSPHERE AND ATMOSPHERIC CHEMISTRY
14.1 The Atmosphere and Atmospheric Chemistry
14.2 Importance of the Atmosphere
14.3 Physical Characteristics of the Atmosphere
14.4 Energy Transfer in the Atmosphere
14.5 Atmospheric Mass Transfer, Meteorology, and Weather
14.6 Inversions and Air Pollution
14.7 Global Climate and Microclimate
14.8 Chemical and Photochemical Reactions in the Atmosphere
14.9 Acid–Base Reactions in the Atmosphere
14.10 Reactions of Atmospheric Oxygen
14.11 Reactions of Atmospheric Nitrogen
14.12 Atmospheric Water Chapter Summary
CHAPTER 15 INORGANIC AIR POLLUTANTS
15.1 Introduction
15.2 Particles in the Atmosphere
15.3 The Composition of Inorganic Particles
15.4 Effects of Particles
15.5 Control of Particulate Emissions
15.6 Carbon Oxides
15.7 Sulfur Dioxide Sources and the Sulfur Cycle
15.8 Nitrogen Oxides in the Atmosphere
15.9 Acid Rain
15.10 Fluorine, Chlorine, and their Gaseous Compounds
15.11 Hydrogen Sulfide, Carbonyl Sulfide, and Carbon Disulfide Chapter Summary
CHAPTER 16 ORGANIC AIR POLLUTANTS AND PHOTOCHEMICAL SMOG
16.1 Organic Compounds in the Atmosphere
16.2 Organic Compounds from Natural Sources
16.3 Pollutant Hydrocarbons
16.4 Nonhydrocarbon Organic Compounds in the Atmosphere
16.5 Photochemical Smog
16.6 Smog-Forming Automotive Emissions
16.7 Smog-Forming Reactions of Organic Compounds in the
Atmosphere
16.8 Mechanisms of Smog Formation
16.9 Inorganic Products from Smog
16.10 Effects of Smog Chapter Summary
CHAPTER 17 THE GEOSPHERE AND GEOCHEMISTRY
17.1 Introduction
17.2 The Nature of Solids in the Geosphere
17.3 Physical Form of the Geosphere
17.5 Clays
17.6 Geochemistry
17.7 Groundwater in the Geosphere
17.8 Environmental Aspects of the Geosphere
17.9 Earthquakes
17.10 Volcanoes
17.11 Surface Earth Movement
17.12 Stream and River Phenomena
17.13 Phenomena at the Land/Ocean Interface
17.14 Phenomena at the Land/Atmosphere Interface
17.15 Effects of Ice
17.16 Effects of Human Activities
17.17 Air Pollution and the Geosphere
17.18 Water Pollution and the Geosphere
17.19 Waste Disposal and the Geosphere Chapter Summary
CHAPTER 18 SOIL ENVIRONMENTAL CHEMISTRY
18.1 Soil and Agriculture
18.2 Nature and Composition of Soil
18.3 Acid-Base and Ion Exchange Reactions in Soils
18.4 Macronutrients in Soil
18.5 Nitrogen, Phosphorus, and Potassium in Soil
18.6 Micronutrients in Soil
18.7 Fertilizers
18.8 Wastes and Pollutants in Soil
18.9 Soil Loss and Degradation
18.10 Genetic Engineering and Agriculture
18.11 Agriculture and Health Chapter Summary
CHAPTER 19 INDUSTRIAL ECOLOGY AND ENVIRONMENTAL CHEMISTRY
19.1 Introduction and History
19.2 Industrial Ecosystems
19.3 The Five Major Components of an Industrial Ecosystem
19.4 Industrial Metabolism
19.5 Levels of Materials Utilization
19.6 Links to Other Environmental Spheres
19.7 Consideration of Environmental Impacts in Industrial Ecology
19.8 Three Key Attributes: Energy, Materials, Diversity
19.9 Life Cycles: Expanding and Closing the Materials Loop
19.10 Life-Cycle Assessment
19.11 Consumable, Recyclable, and Service (Durable) Products
19.12 Design for Environment
19.13 Overview of an Integrated Industrial Ecosystem
19.14 The Kalundborg Example
19.15 Societal Factors and the Environmental Ethic Chapter Summary
CHAPTER 20 GREEN CHEMISTRY FOR A SUSTAINABLE FUTURE
20.1 Introduction
20.2 The Key Concept of Atom Economy
20.3 Hazard Reduction
20.7 The Special Importance of Solvents
20.8 Synthetic and Processing Pathways
20.9 The Role of Catalysts
20.10 Biological Alternatives
20.11 Applications of Green Chemistry Chapter Summary
CHAPTER 21 NATURE, SOURCES, AND ENVIRONMENTAL CHEMISTRY OF HAZARDOUS WASTES
21.1 Introduction
21.2 Classification of Hazardous Substances and Wastes
21.3 Sources of Wastes
21.4 Flammable and Combustible Substances
21.5 Reactive Substances
21.6 Corrosive Substances
21.7 Toxic Substances
21.8 Physical Forms and Segregation of Wastes
21.9 Environmental Chemistry of Hazardous Wastes
21.10 Physical and Chemical Properties of Hazardous Wastes
21.11 Transport, Effects, and Fates of Hazardous Wastes
21.12 Hazardous Wastes and the Anthrosphere
21.13 Hazardous Wastes in the Geosphere
21.14 Hazardous Wastes in the Hydrosphere
21.15 Hazardous Wastes in the Atmosphere
21.16 Hazardous Wastes in the Biosphere Chapter Summary
CHAPTER 22 INDUSTRIAL ECOLOGY FOR WASTE MINIMIZATION, UTILIZATION, AND TREATMENT
22.1 Introduction
22.2 Waste Reduction and Minimization
22.3 Recycling
22.4 Physical Methods of Waste Treatment
22.5 Chemical Treatment: An Overview
22.6 Photolytic Reactions
22.7 Thermal Treatment Methods
22.8 Biodegradation of Wastes
22.9 Land Treatment and Composting
22.10 Preparation of Wastes for Disposal
22.11 Ultimate Disposal of Wastes
22.12 Leachate and Gas Emissions
22.13 In-Situ Treatment Chapter Summary
CHAPTER 23 TOXICOLOGICAL CHEMISTRY
23.1 Introduction to Toxicology and Toxicological Chemistry
23.2 Dose-Response Relationships
23.3 Relative Toxicities
23.4 Reversibility and Sensitivity
23.5 Xenobiotic and Endogenous Substances
23.6 Toxicological Chemistry
23.7 Kinetic Phase and Dynamic Phase
23.8 Teratogenesis, Mutagenesis, Carcinogenesis, and Effects on the Immune and Reproductive Systems
23.9 ATSDR Toxicological Profiles
23.10 Toxic Elements and Elemental Forms
23.11 Toxic Inorganic Compounds
23.12 Toxic Organometallic Compounds
23.13 Toxicological Chemistry of Organic Compounds Chapter Summary
CHAPTER 24 INDUSTRIAL ECOLOGY, RESOURCES, AND ENERGY
24.1 Introduction
24.2 Minerals in the Geosphere
24.3 Extraction and Mining
24.4 Metals
24.5 Metal Resources and Industrial Ecology
24.6 Nonmetal Mineral Resources
24.7 Phosphates
24.8 Sulfur
24.9 Wood—a Major Renewable Resource
24.10 The Energy Problem
24.11 World Energy Resources
24.12 Energy Conservation
24.13 Energy Conversion Processes
24.14 Petroleum and Natural Gas
24.15 Coal
24.16 Nuclear Fission Power
24.17 Nuclear Fusion Power
24.18 Geothermal Energy
24.19 The Sun: an Ideal Energy Source
24.20 Energy from Biomass
24.21 Future Energy Sources
24.22 Extending Resources through the Practice of Industrial Ecology Chapter Summary
CHAPTER 25 FUNDAMENTALS OF ANALYTICAL CHEMISTRY
25.1 Nature and Importance of Chemical Analysis
25.2 The Chemical Analysis Process
25.3 Major Categories of Chemical Analysis
25.4 Error and Treatment of Data
25.5 Gravimetric Analysis
25.6 Volumetric Analysis: Titration
25.7 Spectrophotometric Methods
25.8 Electrochemical Methods of Analysis
25.9 Chromatography
25.10 Mass Spectrometry
25.11 Automated Analyses
25.12 Immunoassay Screening Chapter Summary
CHAPTER 26 ENVIRONMENTAL AND XENOBIOTICS ANALYSIS
26.1 Introduction to Environmental Chemical Analysis
26.2 Analysis of Water Samples
26.3 Classical Methods of Water Analysis
26.4 Instrumental Methods of Water Analysis
26.5 Analysis of Wastes and Solids
26.6 Toxicity Characteristic Leaching Procedure
26.7 Atmospheric Monitoring
26.8 Analysis of Biological Materials and Xenobiotics Chapter Summary
Manahan, Stanley E. "INTRODUCTION TO CHEMISTRY" Fundamentals of Environmental Chemistry Boca Raton: CRC Press LLC,2001
1 INTRODUCTION TO CHEMISTRY
1.1 CHEMISTRY AND ENVIRONMENTAL CHEMISTRY
Chemistry is defined as the science of matter. Therefore, it deals with the air we breathe, the water we drink, the soil that grows our food, and vital life substances and processes. Our own bodies contain a vast variety of chemical substances and are tremendously sophisticated chemical factories that carry out an incredible number of complex chemical processes.
There is a tremendous concern today about the uses—and particularly the mis- uses—of chemistry as it relates to the environment. Ongoing events serve as constant reminders of threats to the environment ranging from individual exposures to toxicants to phenomena on a global scale that may cause massive, perhaps cata- strophic, alterations in climate. These include, as examples, evidence of a perceptible warming of climate; record weather events—particularly floods—in the United States in the 1990s; and air quality in Mexico City so bad that it threatens human health. Furthermore, large numbers of employees must deal with hazardous substances and wastes in laboratories and the workplace. All such matters involve environmental chemistry for understanding of the problems and for arriving at solutions to them.
Environmental chemistry is that branch of chemistry that deals with the origins, transport, reactions, effects, and fates of chemical species in the water, air, earth, and living environments and the influence of human activities thereon. 1 A related discipline, toxicological chemistry, is the chemistry of toxic substances with empha- sis upon their interaction with biologic tissue and living systems. 2 Besides its being an essential, vital discipline in its own right, environmental chemistry provides an excellent framework for the study of chemistry, dealing with “general chemistry,” organic chemistry, chemical analysis, physical chemistry, photochemistry, geo- chemistry, and biological chemistry. By necessity it breaks down the barriers that tend to compartmentalize chemistry as it is conventionally addressed. Therefore, this book is written with two major goals—to provide an overview of chemical science within an environmental chemistry framework and to provide the basics of environmental Environmental chemistry is that branch of chemistry that deals with the origins, transport, reactions, effects, and fates of chemical species in the water, air, earth, and living environments and the influence of human activities thereon. 1 A related discipline, toxicological chemistry, is the chemistry of toxic substances with empha- sis upon their interaction with biologic tissue and living systems. 2 Besides its being an essential, vital discipline in its own right, environmental chemistry provides an excellent framework for the study of chemistry, dealing with “general chemistry,” organic chemistry, chemical analysis, physical chemistry, photochemistry, geo- chemistry, and biological chemistry. By necessity it breaks down the barriers that tend to compartmentalize chemistry as it is conventionally addressed. Therefore, this book is written with two major goals—to provide an overview of chemical science within an environmental chemistry framework and to provide the basics of environmental
1.2 A MINI-COURSE IN CHEMISTRY
It is much easier to learn chemistry if one already knows some chemistry! That is, in order to go into any detail on any chemical topic, it is extremely helpful to have some very rudimentary knowledge of chemistry as a whole. For example, a crucial part of chemistry is an understanding of the nature of chemical compounds, the chemical formulas used to describe them, and the chemical bonds that hold them together; these are topics addressed in Chapter 3 of this book. However, to understand these concepts, it is very helpful to know some things about the chemical reactions by which chemical compounds are formed, as addressed in Chapter 4. To work around this problem, Chapter 1 provides a highly condensed, simplified, but meaningful overview of chemistry to give the reader the essential concepts and terms required to understand more-advanced chemical material.
1.3 THE BUILDING BLOCKS OF MATTER
All matter is composed of only about a hundred fundamental kinds of matter called elements . Each element is made up of very small entities called atoms ; all atoms of the same element behave identically chemically. The study of chemistry, therefore, can logically begin with elements and the atoms of which they are composed.
Subatomic Particles and Atoms
Figure 1.1 represents an atom of deuterium, a form of the element hydrogen. It is seen that such an atom is made up of even smaller subatomic particles—positively charged protons, negatively charged electrons, and uncharged (neutral) neutrons. Protons and neutrons have relatively high masses compared with electrons and are
contained in the positively charged nucleus of the atom. The nucleus has essentially all
the mass, but occupies virtually none of the volume, of
Nucleus
Electron “cloud”
Figure 1.1 Representation of a deuterium atom. The nucleus contains one proton (+) and one neutron (n). The electron (-) is in constant, rapid motion around the nucleus, forming a cloud of nega- tive electrical charge, the density of which drops off with increasing distance from the nucleus.
the atom. An uncharged atom has the same number of electrons as protons. The electrons in an atom are contained in a cloud of negative charge around the nucleus that occupies most of the volume of the atom.
Atoms and Elements
All of the literally millions of different substances are composed of only around 100 elements. Each atom of a particular element is chemically identical to every other atom and contains the same number of protons in its nucleus. This number of protons in the nucleus of each atom of an element is the atomic number of the element. Atomic numbers are integers ranging from 1 to more than 100, each of which denotes a particular element. In addition to atomic numbers, each element has a name and a chemical symbol, such as carbon, C; potassium, K (for its Latin name kalium); or cadmium, Cd. In addition to atomic number, name, and chemical symbol, each element has an atomic mass (atomic weight). The atomic mass of each element is the average mass of all atoms of the element, including the various isotopes of which it consists. The atomic mass unit, u (also called the dalton), is used to express masses of individual atoms and molecules (aggregates of atoms). These terms are summarized in Figure 1.2 .
An atom of carbon, symbol C. An atom of nitrogen, symbol N. Each C atom has 6 protons (+)
Each N atom has 7 protons (+) in its nucleus, so the atomic
in its nucleus, so the atomic number of C is 6. The atomic
number of N is 7. The atomic mass of C is 12.
mass of N is 14.
Figure 1.2 Atoms of carbon and nitrogen Although atoms of the same element are chemically identical, atoms of most
elements consist of two or more isotopes that have different numbers of neutrons in their nuclei. Some isotopes are radioactive isotopes or radionuclides, which have unstable nuclei that give off charged particles and gamma rays in the form of radioactivity . This process of radioactive decay changes atoms of a particular element to atoms of another element.
Throughout this book reference is made to various elements. A list of the known elements is given on page 120 at the end of Chapter 3. Fortunately, most of the chemistry covered in this book requires familiarity with only about 25 or 30 elements. An abbreviated list of a few of the most important elements that the reader should learn at this point is given in Table 1.1 .
Table 1.1 List of Some of the More Important Common Elements
Element Symbol Atomic Number Atomic Mass (relative to carbon-12) Argon
Ar
Bromine Br
Chlorine Cl
Copper Cu
Magnesium Mg
Neon Ne
Nitrogen N
Oxygen O
Potassium K
Silicon Si
Sodium Na
Sulfur S
The Periodic Table
When elements are considered in order of increasing atomic number, it is observed that their properties are repeated in a periodic manner. For example, elements with atomic numbers 2, 10, and 18 are gases that do not undergo chemical reactions and consist of individual molecules, whereas those with atomic numbers larger by one—3, 11, and 19—are unstable, highly reactive metals. An arrangement of the elements in a manner that reflects this recurring behavior is known as the periodic table ( Figure 1.3 ). The periodic table is extremely useful in understanding chemistry and predicting chemical behavior. The entry for each element in the periodic table gives the element’s atomic number, name, symbol, and atomic mass. More-detailed versions of the table include other information as well.
© 2001 CRC Press LLC
Features of the Periodic Table
The periodic table gets its name from the fact that the properties of elements are repeated periodically in going from left to right across a horizontal row of elements. The table is arranged such that an element has properties similar to those of other elements above or below it in the table. Elements with similar chemical properties are called groups of elements and are contained in vertical columns in the periodic table.
1.4. CHEMICAL BONDS AND COMPOUNDS
Only a few elements, particularly the noble gases, exist as individual atoms; most atoms are joined by chemical bonds to other atoms. This can be illustrated very simply by elemental hydrogen, which exists as molecules, each consisting of 2 H atoms linked by a chemical bond as shown in Figure 1.4 . Because hydrogen molecules contain 2 H atoms, they are said to be diatomic and are denoted by the
chemical formula H 2 . The H atoms in the H 2 molecule are held together by a covalent bond made up of 2 electrons, each contributed by one of the H atoms, and shared between the atoms.
The H atoms in are held together by chem- that have the chem- elemental hydrogen ical bonds in molecules ical formula H 2 .
Figure 1.4 Molecule of H 2 .
Chemical Compounds
Most substances consist of two or more elements joined by chemical bonds. As an example, consider the chemical combination of the elements hydrogen and oxygen shown in Figure 1.5 . Oxygen, chemical symbol O, has an atomic number of 8 and an
atomic mass of 16.00 and exists in the elemental form as diatomic molecules of O 2 . Hydrogen atoms combine with oxygen atoms to form molecules in which 2 H atoms are bonded to 1 O atom in a substance with a chemical formula of H 2 O (water). A
substance such as H 2 O that consists of a chemically bonded com-
Hydrogen atoms and To form molecules in The chemical formula of oxygen atoms bond
the resulting compound, together
which 2 H atoms are
attached to 1 O atom. water is H 2 O.
Figure 1.5 A molecule of water, H 2 O, formed from 2 H atoms and 1 O atom held together by chemical bonds.
bination of two or more elements is called a chemical compound. (A chemical compound is a substance that consists of atoms of two or more different elements bonded together.) In the chemical formula for water the letters H and O are the chemical symbols of the two elements in the compound and the subscript 2 indicates that there are 2 H atoms per O atom. (The absence of a subscript after the O denotes the presence of just 1 O atom in the molecule.) Each of the chemical bonds holding a hydrogen atom to the oxygen atom in the water molecule is composed of two electrons shared between the hydrogen and oxygen atoms.
Ionic Bonds
As shown in Figure 1.6 , the transfer of electrons from one atom to another produces charged species called ions. Positively charged ions are called cations and negatively charged ions are called anions. Ions that make up a solid compound are
held together by ionic bonds in a crystalline lattice consisting of an ordered arrangement of the ions in which each cation is largely surrounded by anions and each anion by cations. The attracting forces of the oppositely charged ions in the crystalline lattice constitute the ionic bonds in the compound.
The formation of the ionic compound magnesium oxide is shown in Figure 1.6 . In naming this compound, the cation is simply given the name of the element from which it was formed, magnesium. However, the ending of the name of the anion, oxide, is different from that of the element from which it was formed, oxygen.
2e- 2+ Mg ion O 2 - ion 12e-
10e- Mg
Atom nucleus The transfer of two electrons from yields an ion of Mg 2+ 2 and one of
an atom of Mg to an O atom O - in the compound MgO.
Figure 1.6 Ionic bonds are formed by the transfer of electrons and the mutual attraction of oppositely charged ions in a crystalline lattice.
Rather than individual atoms that have lost or gained electrons, many ions are groups of atoms bonded together covalently and having a net charge. A common
example of such an ion is the ammonium ion, NH + 4 ,
H NH
Ammonium ion, NH + 4
consisting of 4 hydrogen atoms covalently bonded to a single nitrogen (N) atom and having a net electrical charge of +1 for the whole cation.
Summary of Chemical Compounds and the Ionic Bond
The preceding several pages have just covered some material on chemical com- pounds and bonds that are essential to understand chemistry. To summarize, these are the following:
• Atoms of two or more different elements can form chemical bonds with each other to yield a product that is entirely different from the elements.
• Such a substance is called a chemical compound. • The formula of a chemical compound gives the symbols of the elements
and uses subscripts to show the relative numbers of atoms of each element in the compound.
• Molecules of some compounds are held together by covalent bonds
consisting of shared electrons. • Another kind of compound consists of ions composed of electrically
charged atoms or groups of atoms held together by ionic bonds that exist because of the mutual attraction of oppositely charged ions.
Molecular Mass
The average mass of all molecules of a compound is its molecular mass (formerly called molecular weight). The molecular mass of a compound is calculated by multiplying the atomic mass of each element by the relative number of atoms of the element, then adding all the values obtained for each element in the compound.
For example, the molecular mass of NH 3 is 14.0 + 3 x 1.0 = 17.0. As another example consider the following calculation of the molecular mass of ethylene, C 2 H 4 .
1. The chemical formula of the compound is C 2 H 4 .
2. Each molecule of C 2 H 4 consists of 2 C atoms and 4 H atoms.
3. From the periodic table or Table 1.1 , the atomic mass of C is 12.0 and that of H is 1.0.
4. Therefore, the molecular mass of C 2 H 4 is
12.0 + 12.0 + 1.0 + 1.0 + 1.0 + 1.0 = 28.0 From 2 C atoms From 4 H atoms
1.5. CHEMICAL REACTIONS AND EQUATIONS
Chemical reactions occur when substances are changed to other substances through the breaking and formation of chemical bonds. For example, water is produced by the chemical reaction of hydrogen and oxygen:
Hydrogen plus oxygen yields water
Chemical reactions are written as chemical equations. The chemical reaction between hydrogen and water is written as the balanced chemical equation
(1.5.1) in which the arrow is read as “yields” and separates the hydrogen and oxygen
2H 2 + O 2 → 2H 2 O
reactants from the water product. Note that because elemental hydrogen and elemental oxygen occur as diatomic molecules of H 2 and O 2 , respectively, it is necessary to write the equation in a way that reflects these correct chemical formulas of the elemental form. All correctly written chemical equations are balanced, in that they must show the same number of each kind of atom on both sides of the equation . The equation above is balanced because of the following:
On the left • There are 2 H 2 molecules, each containing 2 H atoms for a total of 4 H
atoms on the left. • There is 1 O 2 molecule, containing 2 O atoms for a total of 2 O atoms on
the left. On the right • There are 2 H 2 O molecules each containing 2 H atoms and 1 O atom for
a total of 4 H atoms and 2 O atoms on the right. The process of balancing chemical equations is relatively straightforward for
simple equations. It is discussed in Chapter 4.
1.6. NUMBERS IN CHEMISTRY: EXPONENTIAL NOTATION
An essential skill in chemistry is the ability to handle numbers, including very large and very small numbers. An example of the former is Avogadro’s number, which is discussed in detail in Chapters 2 and 3. Avogadro’s number is a way of expressing quantities of entities such as atoms or molecules and is equal to 602,000,000,000,000,000,000,000. A number so large written in this decimal form is very cumbersome to express and very difficult to handle in calculations. It can be expressed much more conveniently in exponential notation. Avogadro’s number in
exponential notation is 6.02 × 10 23 . It is put into decimal form by moving the decimal in 6.02 to the right by 23 places. Exponential notation works equally well to express very small numbers, such as 0.000,000,000,000,000,087. In exponential notation this
number is 8.7 × 10- 17 . To convert this number back to decimal form, the decimal point in 8.7 is simply moved 17 places to the left.
A number in exponential notation consists of a digital number equal to or greater than exactly 1 and less than exactly 10 (examples are 1.00000, 4.3, 6.913, 8.005, 9.99999) multiplied by a power of 10 (10- 17 , 10 13 , 10- 5 , 10 3 , 10 23 ). Some examples of numbers expressed in exponential notation are given in Table 1.2 . As seen in the second column of the table, a positive power of 10 shows the number of times that the digital number is multiplied by 10 and a negative power of 10 shows A number in exponential notation consists of a digital number equal to or greater than exactly 1 and less than exactly 10 (examples are 1.00000, 4.3, 6.913, 8.005, 9.99999) multiplied by a power of 10 (10- 17 , 10 13 , 10- 5 , 10 3 , 10 23 ). Some examples of numbers expressed in exponential notation are given in Table 1.2 . As seen in the second column of the table, a positive power of 10 shows the number of times that the digital number is multiplied by 10 and a negative power of 10 shows
Table 1.2 Numbers in Exponential and Decimal Form
Places decimal moved Decimal Exponential form of number
for decimal form form
1.37 × 10 5 = 1.37 × 10 × 10 × 10 × 10 × 10 → 5 places 137,000
7.19 × 10 7 = 7.19 × 10 × 10 × 10 × 10 × 10 → 7 places 71,900,000 × 10 × 10
3.25 × 10 - 2 = 3.25/(10 × 10) ← 2 places 0.0325
2.6 × 10 - 6 = 2.6/(10 × 10 × 10 × 10 × 10 × 10) ← 6 places 0.000 0026
5.39 × 10 - 5 = 5.39/(10 × 10 × 10 × 10 × 10)
← 5 places 0.000 0539
Addition and Subtraction of Exponential Numbers
An electronic calculator keeps track of exponents automatically and with total accuracy. For example, getting the sum 7.13 × 10 3 + 3.26 × 10 4 on a calculator simply involves the following sequence:
7.13 EE3 + 3.26 EE4 = 3.97 EE4
where 3.97 EE4 stands for 3.97 × 10 4 . To do such a sum manually, the largest number in the sum should be set up in the standard exponential notation form and each of the other numbers should be taken to the same power of 10 as that of the
largest number as shown, below for the calculation of 3.07 × 10- 2 - 6.22 × 10- 3 +
4.14 × 10- 4 :
3.07 × 10- 2 (largest number, digital portion between 1 and 10)
- 0.622 × 10 - 2 (same as 6.22 x 10 - 3 )
+ 0.041 × 10- 2 (same as 4.1 x 10 - 4 )
Answer: 2.49 × 10- 2
Multiplication and Division of Exponential Numbers
As with addition and subtraction, multiplication and division of exponential numbers on a calculator or computer is simply a matter of (correctly) pushing buttons. For example, to solve
1.39 × 10- 2 × 9.05 × 10 8
3.11 × 10 4 on a calculator, the sequence below is followed:
1.39 EE-2 9.05 EE8 ÷ 3.11 EE4 = 4.04 EE2 (same as 4.04 x 10 2 )
In multiplication and division of exponential numbers, the digital portions of the numbers are handled conventionally. For the powers of 10, in multiplication exponents are added algebraically, whereas in division the exponents are subtracted algebraically. Therefore, in the preceding example,
1.39 2 × 10- × 9.05 × 10 8
3.11 × 4 10 the digital portion is
3.11 and the exponential portion is,
10- 2 × 10 8 = 10 2 (The exponent is -2 + 8 - 4)
So the answer is 4.04 x10 2 .
Example: Solve
without using exponential notation on the calculator. Answer: Exponent of answer = -2 + 5 - (4 - 3) = 2
Algebraic addition of exponents Algebraic subtraction of exponents in the numerator in the denominator
4.09 = 13.2 The answer is 13.2 × 10 2 = 1.32 x 10 3
2.22 × 1.03 Example: Solve
3.26 × 10 18 × 7.47 × 10- 5 × 6.18 × 10- 8 Answer: 2.32 × 10- 4
1.7 SIGNIFICANT FIGURES AND UNCERTAINTIES IN NUMBERS
The preceding section illustrated how to handle very large and very small numbers with exponential notation. This section considers uncertainties in numbers, taking into account the fact that numbers are known only to a certain degree of accuracy. The accuracy of a number is shown by how many significant figures or significant digits it contains. This can be illustrated by considering the atomic masses of elemental boron and sodium. The atomic mass of boron is given as
10.81. Written in this way, the number expressing the atomic mass of boron contains 10.81. Written in this way, the number expressing the atomic mass of boron contains
0.01. The atomic mass of sodium is given as 22.98977, a number with seven significant digits understood to mean 22.98977 ± 0.00001. Therefore, the atomic mass of sodium is known with more certainty than that of boron. The atomic masses in Table 1.1 reflect the fact that they are known with much more certainty for some elements (for example fluorine, 18.998403) than for others (for example, calcium listed with an atomic mass of 40.08).
The rules for expressing significant digits are summarized in Table 1.3 . It is important to express numbers to the correct number of significant digits in chemical calculations and in the laboratory. The use of too many digits implies an accuracy in the number that does not exist and is misleading. The use of too few significant digits does not express the number to the degree of accuracy to which it is known.
Table 1.3 Rules for Use of Significant Digits
Example Number of sig- number nificant digits Rule
5 1. Non-zero digits in a number are always significant. The 1,1,3,9, and 7 in this number are each significant.
6 2. Zeros between non-zero digits are significant. The 1,
4, 0, 0, 3, and 9 in this number are each significant. 0.00329
3 3. Zeros on the left of the first non-zero digit are not significant because they are used only to locate the decimal point. Only 3, 2, and 9 in this number are significant.
70.00 4 4. Zeros to the right of a decimal point that are preceded by a significant figure are significant. All three 0s, as well as the 7, are significant.
32 000 Uncertain
5. The number of significant digits in a number with zeros to the left, but not to the right of a decimal point (1700, 110 000) may be uncertain. Such numbers should be written in exponential notation.
3.20 x 10 3 3 6. The number of significant digits in a number written in exponential notation is equal to the number of sig- nificant digits in the decimal portion.
Exactly 50 Unlimited
7. Some numbers, such as the amount of money that one expects to receive when cashing a check or the num- ber of children claimed for income tax exemptions, are defined as exact numbers without any uncer- tainty.
Exercise: Referring to Table 1.3 , give the number of significant digits and the rule(s) upon which they are based for each of the following numbers:
(a) 17.000
(c) 7.001 (d) $50
(i) 0.05029 Answers: (a) 5, Rule 4; (b) 5, Rule 1; (c) 4, Rule 2; (d) exact number; (e) 3, Rules 3
(g) 6.207 × 10- 7 (h) 13.5269184
and 4; (f) uncertain, Rule 5; (g) 4, Rule 6; (h) 9, Rule 1; (i) 4 Rules 2 and 3
Significant Figures in Calculations
After numbers are obtained by a laboratory measurement, they are normally subjected to mathematical operations to get the desired final result. It is important that the answer have the correct number of significant figures. It should not have so few that accuracy is sacrificed or so many that an unjustified degree of accuracy is implied. The two major rules that apply, one for addition/subtraction, the other for multiplication/division, are the following:
1. In addition and subtraction, the number of digits retained to the right of the decimal point should be the same as that in the number in the calcula- tion with the fewest such digits.
Example: 273.591 + 1.00327 + 229.13 = 503.72427 is rounded to 503.72 because 229.13 has only two significant digits beyond the decimal.
Example: 313.4 + 11.0785 + 229.13 = 553.6085 is rounded to 553.6 because 313.4 has only one significant digit beyond the decimal.
2. The number of significant figures in the result of multiplication/division should be the same as that in the number in the calculation having the fewest significant figures.
Example: 3.7218 x 4.019 x 10 = 1.0106699 × 10- 2 is rounded to
1.01 x10- 2 (3 significant figures because 1.48 has only 3 significant figures) Example: 5.27821 × 10 7 × 7.245 × 10- 5 = 3.7962744 × 10 3 is rounded
1.00732 to 3.796 × 10 3 (4 significant figures because 7.245 has only 4 significant
figures) It should be noted that an exact number is treated in calculations as though it has an
unlimited number of significant figures.
Exercise: Express each of the following to the correct number of significant figures:
(a) 13.1 + 394.0000 + 8.1937 (b) 1.57 × 10- 4 × 7.198 × 10- 2 (c) 189.2003 - 13.47 - 2.563
(d) 221.9 × 54.2 × 123.008 (e) 603.9 × 21.7 × 0.039217 (f) 3.1789 × 10- 3 × 7.000032 × 10 4
(g) 100 × 0.7428 × 6.82197 (where 100 is an exact number) Answers: (a) 415.3, (b) 1.13 × 10- 5 , (c) 173.17, (d) 1.48 × 10 6 , (e) 5.9,
(f) 8.2019, (g) 506.7
Rounding Numbers
With an electronic calculator it is easy to obtain a long string of digits that must be rounded to the correct number of significant figures. The rules for doing this are the following: