chapter2.pdf

ENVIRONMENTAL SCIENCE 13e CHAPTER 2: Science, Matter, and Energy  Core Case Study: A Story about a Forest (1) Hubbard Brook Experimental Forest Question: What is the environmental impact of forest clear-cutting? Controlled experiment – isolate variables – C...

ENVIRONMENTAL SCIENCE 13e CHAPTER 2: Science, Matter, and Energy  Core Case Study: A Story about a Forest (1) Hubbard Brook Experimental Forest Question: What is the environmental impact of forest clear-cutting? Controlled experiment – isolate variables – Control group – Experimental group  Core Case Study: A Story about a Forest (2) Measure loss of water and nutrients Compare results – 30–40% increase in runoff – 6–8 times more nutrient loss Draw conclusions – Cause-and-effect relationships Fig. 2-1, p. 23 Fig. 2-3, p. 30  60 Nitrate (NO3– ) concentration (milligrams per liter) 40 Undisturbed Disturbed (control) (experimental) 20 watershed watershed 1963 1964 1965 1966 1967 1968 1969 1970 1970 1972 Year Fig. 2-3, p. 30  2-1 What Do Scientists Do? Concept 2-1 Scientists collect data and develop theories, models, and laws about how nature works.  Science Search for order in nature – Observe behavior – Attempt to identify cause and effect – Make predictions – Test predictions – Draw conclusions  The Scientific Process (1) Identify problem/question Learn what is known about problem/question Ask question to be investigated Collect data Formulate a testable scientific hypothesis  The Scientific Process (2) Make testable projections Test projections with experiments Develop models Propose scientific theories Derive natural laws  The Scientific Process (3) Four features of the scientific process: – Curiosity – Skepticism – Peer review – Reproducibility Fig. 2-2, p. 25  Identify a problem Find out what is known about the problem (literature search) Ask a question to be investigated Perform an experiment to answer the question and collect data Scientific law Analyze data Well-accepted (check for patterns) pattern in data Fig. 2-2, p. 25  Propose an hypothesis to explain data Use hypothesis to make testable predictions Perform an experiment to test predictions Accept Revise Make testable hypothesis hypothesis predictions Test predictions Scientific theory Well-tested and widely accepted hypothesis Fig. 2-2, p. 25  Identify a problem Find out what is known about the problem (literature search) Ask a question to be investigated Perform an experiment to answer the question and collect data Scientific law Analyze data Well-accepted (check for patterns) pattern in data Propose an hypothesis to explain data Use hypothesis to make testable predictions Perform an experiment to test predictions Accept Revise Make testable hypothesis hypothesis predictions Test predictions Scientific theory Well-tested and Stepped Art widely accepted hypothesis Fig. 2-2, p. 25  Results of Science Goals – Scientific theories – Scientific laws Degree of certainty and general acceptance – Frontier/tentative science – Reliable science – Unreliable science  Scientific Limitations Limitations – 100% certain? – Absolute proof versus probability – Observational bias – Complex interactions, many variables – Estimates and extrapolating numbers – Mathematical models Science Focus: Climate Change (1) Natural greenhouse effect – Keeps atmosphere temperatures moderate Three questions 1. How much warming over the last 50 years? 2. How much of the warming is caused by humans adding carbon dioxide to atmosphere? 3. How much will the atmosphere warm in the future, and what effects will it have? Science Focus: Climate Change (2) International Panel on Climate Change 2007 IPCC report: – Very likely: 0.74 C° increase 1906-2005 – Very likely: human activities main cause of global warming – Likely: earth mean surface temperature to increase by ~3 C ° between 2005 and 2100. Climate change critics: most are not climate experts  2-2 What Is Matter and How Do Physical and Chemical Changes Affect It? Concept 2-2A Matter consists of elements and compounds, which are in turn made up of atoms, ions, or molecules. Concept 2-2B Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).  What Is Matter? Matter – has mass and occupies space Elements and Compounds – Atoms – Ions – Molecules Table 2-1, p. 29  Building Blocks of Matter (1) Atomic Theory – elements made from atoms Atoms – Protons – positive charge – Neutrons – uncharged – Electrons – negative charge Nucleus – One or more protons – Usually one or more neutrons Supplement 6, Fig. 1, p. S26 6 protons 6 neutrons 6 electrons Supplement 6, Fig. 1, p. S26  Building Blocks of Matter (2) Atomic number – Number of protons Mass number – Neutrons + protons Isotopes – Same atomic number, different mass – Same number of protons, different number of neutrons  Building Blocks of Matter (3) Ion – One or more net positive or negative electrical charges Molecule – Combination of two or more atoms Chemical formula – Number and type of each atom or ion Compounds – Organic – Inorganic Supplement 6, Fig. 6, p. S28  100 Hydrochloric 0 acid (HCl) Gastric fluid 10–1 1 (1.0–3.0) 10–2 2 Lemon juice, some acid rain 10–3 Vinegar, wine, 3 beer, oranges 10–4 Tomatoes 4 Bananas Black coffee 10–5 5 Bread Typical rainwater 10–6 Urine (5.0–7.0) 6 Milk (6.6) 10–7 Pure water 7 Blood (7.3–7.5) 10–8 Egg white (8.0) 8 Seawater (7.8–8.3) Baking soda 10–9 9 Phosphate detergents Bleach, Tums Soapy solutions, 10–10 10 Milk of magnesia Household ammonia 10–11 11 (10.5–11.9) 10–12 12 Hair remover 10–13 13 Oven cleaner Sodium hydroxide (NaOH) 10–14 14 Supplement 6, Fig. 6, p. S28 Supplement 6, Fig. 5, p. S27  H2 O2 N2 CI2 hydrogen oxygen nitrogen chlorine NO CO HCI H2 O nitric oxide carbon monoxide hydrogen chloride water NO2 CO2 SO2 O3 nitrogen dioxide carbon dioxide sulfur dioxide ozone CH4 NH3 SO3 H2S methane ammonia sulfur trioxide hydrogen sulfide Supplement 6, Fig. 5, p. S27 Table 2-2, p. 29 Table 2-3, p. 30  Organic Compounds Carbon-based compounds – Hydrocarbons – Chlorinated hydrocarbons – Simple carbohydrates – Complex carbohydrates – Proteins – Nucleic acids (DNA and RNA) – Lipids  Matter Becomes Life Cells Genes – DNA – Traits Chromosomes – DNA – Proteins Fig. 2-4, p. 31 A human body contains trillions of cells, each with an identical set of genes. Each human cell (except for red blood cells) contains a nucleus. Each cell nucleus has an identical set of chromosomes, which are found in pairs. A specific pair of chromosomes contains one chromosome from each parent. Each chromosome contains a long DNA molecule in the form of a coiled double helix. Genes are segments of DNA on chromosomes that contain instructions to make proteins—the building blocks of life. Fig. 2-4, p. 31 A human body contains trillions of cells, each with an identical set of genes. Each human cell (except for red blood cells) contains a nucleus. Each cell nucleus has an identical set of chromosomes, which are found in pairs. A specific pair of chromosomes contains one chromosome from each parent. Each chromosome contains a long DNA molecule in the form of a coiled double helix. Genes are segments of DNA on chromosomes that contain instructions to make proteins—the building blocks Stepped Art of life. Fig. 2-4, p. 31  Matter Quality Usefulness as a resource – Availability – Concentration High quality Low quality Fig. 2-5, p. 32 High Quality Low Quality Solid Gas Salt Solution of salt in water Coal Coal-fired power plant emissions Gasoline Automobile emissions Aluminum can Aluminum ore Fig. 2-5, p. 32  Changes in Matter Physical Chemical Law of Conservation of Matter – Matter only changes from one form to another p. 32  Reactant(s) Product(s) Carbon + Oxygen Carbon dioxide + Energy C + O2 CO2 + Energy O C + O C O + Energy O Black solid Colorless gas Colorless gas p. 32  Nuclear Changes (1) Radioactive decay – unstable isotopes – Alpha particles – Beta particles – Gamma rays  Nuclear Changes (2) Nuclear fission – Large mass isotopes split apart – Chain reaction Nuclear fusion – Two light isotopes forced together – High temperature to start reaction – Stars Fig. 2-6, p. 33 Radioactive decay Alpha particle Radioactive decay + (helium-4 nucleus) occurs when nuclei of Radioactive isotope + unstable isotopes spontaneously emit fast- moving chunks of matter (alpha particles or beta particles), high-energy Gamma rays radiation (gamma rays), or both at a fixed rate. A particular radioactive isotope may emit any one or a combination of the Beta particle three items shown in the (electron) diagram. Fig. 2-6, p. 33 Nuclear fission Uranium-235 Fission Nuclear fission occurs when the Energy nuclei of certain isotopes with large fragment n mass numbers (such as uranium-235) n are split apart into lighter nuclei when Neutron n n struck by a neutron and release Energy Energy energy plus two or three more n n neutrons. Each neutron can trigger an Uranium-235 additional fission reaction and lead to Fission a chain reaction, which releases an fragment Energy enormous amount of energy. Fig. 2-6, p. 33 Nuclear fusion Reaction Fuel conditions Products Proton Neutron Helium-4 nucleus Hydrogen-2 (deuterium nucleus) Nuclear fusion occurs when two isotopes of light elements, such as hydrogen, are forced together 100 Energy at extremely high temperatures million °C until they fuse to form a heavier nucleus and release a tremendous amount of energy. Hydrogen-3 (tritium nucleus) Neutron Fig. 2-6, p. 33  Uranium-235 Uranium-235 Uranium-235 Energy Fission fragment Uranium-235 n n Neutron n n Energy Energy Uranium-235 Uranium-235 n n Fission Uranium-235 fragment Energy Uranium-235 Uranium-235 Stepped Art Uranium-235 Fig. 2-6, p. 33  2-3 What Is Energy and How Do Physical and Chemical Changes Affect It? Concept 2-3A When energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed (first law of thermodynamics). Concept 2-3B Whenever energy is converted from one form to another in a physical or chemical change, we end up with lower quality or less usable energy than we started with (second law of thermodynamics).  What Is Energy? Energy – the capacity to do work or transfer heat  Types of Energy Potential energy – stored energy – Gasoline – Water behind a dam Kinetic energy – energy in motion – Wind, flowing water, electricity – Heat – flow from warm to cold – Electromagnetic radiation wavelength and relative energy Fig. 2-7, p. 34  15 Energy emitted from sun (kcal/cm2/min) 10 5 Visible Ultraviolet Infrared 0 0.25 1 2 2.5 3 Wavelength (micrometers) Fig. 2-7, p. 34  Energy Quality (1) High-quality energy – Concentrated, high capacity to do work – High-temperature heat – Nuclear fission – Concentrated sunlight – High-velocity wind – Fossil fuels  Energy Quality (2) Low-quality energy – Dispersed – Heat in atmosphere – Heat in ocean  Laws of Thermodynamics First law of thermodynamics – Energy input = Energy output – Energy is neither created or destroyed – Energy only changes from one form to another Second law of thermodynamics – Energy use results in lower-quality energy – Dispersed heat loss  Consequences of the Second Law of Thermodynamics Automobiles – ~13% moves car – ~87% dissipates as low-quality heat into the environment Incandescent light bulb – ~5% useful light – ~95% heat Fig. 2-8, p. 36  Mechanical Chemical energy Chemical Solar energy energy (photo-synthesis) (moving, energy (food) thinking, living) Waste Waste Waste Waste heat heat heat heat Fig. 2-8, p. 36 Three Big Ideas of This Chapter There is no away – Law of conservation of matter You cannot get something for nothing – First law of thermodynamics You cannot break even – Second law of thermodynamics Animation: Subatomic particles Animation: Atomic number, mass number Animation: Ionic bonds Animation: Carbon bonds Animation: Half-life Animation: Visible light Animation: Total energy remains constant Animation: Energy flow Animation: Economic types Animation: Martian doing mechanical work Animation: Energy flow from Sun to Earth Animation: Energy Use Animation: Hubbard Brook Experiment Animation: Categories of Food Webs