1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Enger & Smith Environmental Science A Study of Interrelationships Eleventh Edition Chapter 4 Interrelated Scientific Principles: Matter, Energy, and Environment

3. Outline  The Nature of Science  Limitations of Science  Pseudoscience  The Structure of Matter  Energy Principles  Environmental Implications of Energy Flow

4. The Nature of Science  Envl science involves analysis of data, so we need to understand how scientists gather and evaluate info, some chemical and physical principals for evaluating envl issues.  Science is a process used to solve problems or develop an understanding of nature that involves testing possible answers.  The scientific method is a way of gaining information (facts) about the world by forming possible solutions to questions, followed by rigorous testing to determine if the proposed solutions are valid.

5. Basic Assumptions in Science  Presumptions Specific causes exist for observed events. These causes can be identified. General rules or patterns can be used to describe observations. Repeated events probably have the same cause. Perceptions are not individualistic. Fundamental rules of nature are universal.

6.  Ex: observation: lightening associated w thunderstorms.  Assumption: an explanation that would account for all cases of lightning regardless of where or when they occur & all people make same observations. lightning is caused by a difference in electrical charge the behavior of lightning follows general rules that r the same as those seen w static electricity all lightning that has been measured has same cause wherever and whenever occur.

7. Elements of the Scientific Method  Scientists distinguish between situations that are merely correlated (happen together) and those that are correlated and show cause-and- effect relationships.  The scientific method requires a systematic search for information and continual evaluation to determine if previous ideas are still supported.  Scientific ideas undergo constant reevaluation, criticism, and modification.

8. 8  Scientific method involves careful observation, asking questions about observed events, construct and test hypotheses, an openness to new info and idea and willingness to submit one’s ideas to the scrutiny of others.

9. Elements of the Scientific Method  Observation occurs when we use our senses (smell, touch, sight) or extensions of our senses (microscope, tape recorder, X-ray machine) to record an event. Scientists refer to observations as careful, thoughtful recognitions of events.  Observations often lead to additional questions about the observations. The way questions are asked will determine how one goes about answering them. Scientist train themselves to improve their observational skills. Observation lead to asking questions.  Exploring other sources of knowledge is the next step to gain more information.

10. 10 –Asking the right question is critical in determining how, and where, to look for answers. –This can be the most time-consuming part. –Ex: Robins eat berries of some plants and avoid others. –Two ways to ask a question: Do robins dislike the flavor of some? Will they eat more of one kind of berry if given two kinds? –2 nd is easier to answer. –Literature Exploration: what others already done, has it been answered already.

11. Elements of the Scientific Method  A hypothesis is a testable statement that provides a possible answer to a question, or an explanation for an observation. A good hypothesis must be logical, account for all relevant information currently available, allow prediction of related future events, and be testable. If does not account for all facts, doubt will be cast on the work, if not testable or not supported by evidence the explanation will be only hearsay and not useful. –Given a choice, the simplest hypothesis with the fewest assumptions is the most desirable.

12. 12 –If disprove a hypothesis it needs to be rejected & a new one will be formed. –If not disprove make it more strong but not prove to be true in all cases or all times. Then you have to test your hypothesis.  It can be done in several forms: collection of pertinent info from variety of sources. Ex in cemetery reading tombstones large # of different ages died in same year. Hypothesize epidemic of disease or a natural disaster caused deaths. Getting historical newspaper accounts a way to test. making additional observations: ex certain species of bird used cavities of trees to build nest. Observe many birds of the species and record kinds of nests thy built and where they build them. common way is devising an experiment.

13. Elements of the Scientific Method  An experiment is a re-creation of an event that enables an investigator to support or disprove a hypothesis. A controlled experiment divides the experiment into two groups (experimental and control) that differ by only one variable. The results of a well designed experiment should be able to support or disprove a hypothesis. Not always the case, some results are inconclusive needs a new experiment  Reproducibility is important to the scientific method. A good experiment must be able to be repeated by independent investigators to ensure a lack of bias.

14. Elements of the Scientific Method  When broad consensus exists about an area of science, it is known as a theory or law. A theory is a widely accepted, plausible generalization about fundamental scientific concepts that explains why things happen. Kinetic Molecular Theory: all matter is made up of tiny moving particles. Use to explain why materials disperse in water or air, why change from solids to liquids and why different chemicals interact during reactions. (broad, yrs of observation, experimentation, analysis) –Theory is also often incorrectly used in a much less restrictive sense to describe a vague idea. –Hypothesis provides possible explanation to specific ?, theory a broad concept that shapes how scientists look at the world and how they frame their hypothesis

15. A scientific law is a uniform or constant fact of nature that describes what happens in nature. Law of Conservation of Mass: –matter is not gained or lost during a chemical reaction Law describes what happens & theories say why it happen. In a way they r similar: both been examined repeatedly and r excellent predictors of how nature behaves

16. Elements of the Scientific Method  Communication is a central characteristic of the scientific method.  An important part of the communication process involves the publication of articles in scientific journals about one’s research, thoughts, and opinions.  This provides other scientists with an opportunity to criticize, make suggestions, or agree. A hypothesis supported by many experiments and by different investigators is considered reliable.

17. Elements of the Scientific Method

18. Limitations of Science  Scientists may know more about scientific aspects of issues but can’t analyze issues such as international politics, or if family planning programs should be instituted  Scientists struggle with the same moral and ethical questions as other people & their judgment on these matters can be biased as anyone else’s. It is important to differentiate between data collected during an investigation, and scientists’ opinions of what the data mean. Their opinion may not always be supported by facts.  Scientific knowledge can be used to support both valid and invalid conclusions.  Pseudoscience is a deceptive practice that uses the appearance or language of science to convince, confuse, or mislead people into thinking that something has scientific validity when it does not.

19. The Structure of Matter  Matter is anything that has mass and takes up space. The kinetic molecular theory describes the structure and activity of matter. – It states that all matter is made up of one or more kinds of smaller sub-units (atoms) that are in constant motion. This theory is a central theory that describes the structure & activity of matter.

20. Atomic Structure  The atom is the fundamental unit of matter.  There are 92 types of atoms found in nature, with each being composed of: Protons (Positively charged) Neutrons (Neutral) Electrons (Negatively charged)  Each kind of atom forms a specific type of matter known as an element.  P+N make nucleus. Different combination of P, N & E makes different elements. Ex mercury=80P+80E, gold has 79 of each & oxygen has only 8 each

21. Atomic Structure Diagrammatic oxygen atom.

22. Atomic Structure  All atoms of the same element have the same number of protons and electrons, but may vary in the number of neutrons. Isotopes are atoms of the same element that differ from one another in the number of neutrons they contain.

23. Atomic Structure Isotopes of hydrogen First is the most common isotope 1 P & no neutron=protium Middle is the heavy isotope=deuterium, has 1 P & 1 N Last is Tritium, is radioactive has 1 P & 2 N

24. The Molecular Nature of Matter  In some cases atoms act as individual particles & in other cases they bond to each other making molecules.  Molecules are atoms bonded together into stable units. –Aggregate of at least 2 atoms in a definite arrangement held by special forces. –Smallest particle of a pure substance which retains its composition & chemical properties Ions are electrically charged particles. –Atoms that lose electrons = positively charged –Atoms that gain electrons = negatively charged –Appositively charged ions attract each other & form stable units but split into their individual ions when dissolved

25. The Molecular Nature of Matter  Compounds are formed when two or more atoms or ions bind to one another. Water ( H 2 0 ) Table sugar ( C 6 H 12 O 6 )  Mixtures are variable combinations of atoms, ions, or molecules. Honey (several sugars + water) Concrete (cement, sand, and gravel) Air (various gases including nitrogen and oxygen)

26. Acids, Bases, and pH  Three classes of compounds:  An acid is any compound that releases hydrogen ions in a solution.  A base is any compound that accepts hydrogen ions in a solution/release OH -.(alkali & alkaline) Ex NaOH strong base in oven cleaner.  The concentration of an acid or base solution is given by a number called its pH. The pH scale measures hydrogen ion concentration. The scale is inverse and logarithmic (is Reciprocal=lower mean stronger and is Logarithmic means difference between 2 consecutive pH is 10X difference). –7 = neutral –0-6 = acidic (fewer OH - than H + ) –8-14 = basic (more OH - than H + ) –Higher pH means more OH- concentration and stronger base

27. Acids, Bases, and pH The pH scale.

28. Inorganic and Organic Matter  Organic matter consists of molecules that contain carbon atoms that are usually bonded to form rings or chains. Ex natural gas, oil, coal, sugar, protein, fat All living things contain molecules of organic compounds. –Typically, chemical bonds in organic molecules contain a large amount of chemical energy that can be released when the bonds are broken. –Inorganic molecules consist of small molecules & combination of ions. Ex salt, water, metals, oxygen –Living things must manufacture organic compounds from inorganic ones (producers) or modify organic compounds they obtain from eating organic materials (consumers)

29. Chemical Reactions  Chemical bonds are attractive forces between atoms resulting from the interaction of their electrons. They have certain amount of E When chemical bonds are formed or broken, a chemical reaction occurs. –In exothermic reactions, chemical bonds in the new compounds contain less chemical energy than the previous compounds. Release E as heat or light. Ex burning methane gas –In endothermic reactions, the newly formed chemical bonds contain more energy than the previous compounds. They gain E, need external E to form new bonds

30. Chemical Reactions Water molecule

31. Chemical Reactions A chemical reaction. When methane burned chemical bonds r rearranged & excess chemical bond E is released as light & heat. The same atoms r present in the reactants as in the products but they r bonded in different ways resulting in molecules of new substances.

32. Chemical Reactions  Even E yielding reactions usually need an input of E to get the reactions started.  Activation energy is the initial input of energy required to start a reaction.  A catalyst/enzyme is a substance that alters the rate of reaction, without being consumed or altered itself in the process. Catalysts can reduce activation energy. –A catalytic converter in an automobile brings about more complete burning of fuel, resulting in less air pollution. It helps materials that not completely burned to react further w/o need for high T

33. Chemical Reactions in Living Things  Living organisms r composed of cells which r made of organic & inorganic matter.  Living organisms contain enzymes that reduce the activation energy needed to start reactions.  Since high T needed to start reactions, w/o enzymes living organisms will be destroyed.  Photosynthesis is a process used by plants to convert inorganic material into organic material using light. Carbon dioxide + water (in the presence of sunlight) produces glucose + oxygen. Take place in green portion (chlorophyll). Does all organism need photosynthesis? 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2

34. Chemical Reactions in Living Things Photosynthesis Photosynthesis is endothermic, need sunlight to start reaction

35. Chemical Reactions in Living Things  Respiration is the process that uses oxygen to break down large, organic molecules into smaller inorganic molecules (releases energy organisms can use). Opposite of photosynthesis.  Can organism live w/o it? Glucose + oxygen produces carbon dioxide + water + energy C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + energy

36. Chemical Reactions in Living Things Respiration Respiration involves release of E from organic molecules when they react w oxygen, also produces carbon dioxide and water

37. Energy Principles  Energy is the ability to perform work.  Work is done when an object is moved over a distance. Kinetic energy is the energy contained by moving objects. Ex water running down hill Potential energy is energy due to relative position. Ex water behind a dam, electron moved further from nucleus

38. States of Matter  The state of matter depends on the amount of energy present. The amount of kinetic energy contained in a molecule determines how rapidly it moves. –Solids: Molecular particles have low energy and vibrate in place very close to one another. –Liquids: More energy; molecules are farther apart from one another. –Gases: Molecular particles move very rapidly and are very far apart.

39. Energy Principles States of matter Amount of kinetic E determines how rapidly they move.

40. States of Matter  When 2 forms of matter have different T, heat E will flow from one w higher T to one w lower. It is referred to as: Sensible heat transfer occurs when heat energy flows from a warmer object to a cooler object. Touching a cold or hot object –The temperature of cooler matter increases and the temperature of warmer matter decreases. Latent heat transfer occurs when heat energy is used to change the state of matter, but the temperature of matter does not change. Water evaporate from body

41. First and Second Laws of Thermodynamics  Energy can be converted from one form to another, but the amount remains constant. 1st Law: Energy cannot be created or destroyed; it can only be changed from one form to another. Ex converting other form of E to electricity 2nd Law: When converting energy from one form to another, some of the useful energy is lost. –Entropy is the energy that cannot be used to do useful work. –Entropy Increases during conversion of E. –Entropy is a measure of disorder so increases as E is converted

42. First and Second Laws of Thermodynamics Second law of thermodynamics When E converted, some useful E is lost usually in form of heat. Conversion of fuel E to electricity produces heat that is lost to atmosphere, as electricity moves through wire, resistance generates additional heat when electricity is converted to light in light bulb heat is produced, all steps produce low quality heat in accordance w 2nd law of thermodynamics.

43. Environmental Implications of Energy Flow  Heat produced during energy conversion is dissipated into the environment. All machines & living things that manipulate E release heat.  w/o external E source things move toward disorder. ex Chemical Reactions that cause rust releases heat Friction Between Moving Objects generate heat & causes parts to wear out  Orderly arrangements of matter tend to become disordered. The process of becoming disordered coincides with the constant flow of energy toward a dilute form of heat.  This results in an increase in entropy.  Non-living objects wear out & living ones die.

44. Environmental Implications of Energy Flow  Some forms of energy are more useful than others.  High quality: Can be used to perform useful work (electricity).  Low quality: Cannot be used to perform useful work (heat in the ocean).  Temperature differential between two objects means that heat will flow from the warmer object to the cooler object.  The greater the temperature differential, the more useful work can be done.

45. 45  Because average T of ocean is not high, is hard to find another object w greatly low T, so is difficult to use huge heat content of oceans.  Damming can change quality of E  Still low quality of E is important for world.  We need ways to convert low-quality E to high quality  Organisms such plants r able to convert low quality light E to high quality through photosynthesis

46. Environmental Implications of Energy Flow  Low-quality energy still has significance in the world. The distribution of heat energy in the ocean moderates the temperature of coastal climates. It contributes to weather patterns and causes ocean currents that are important in many ways.  We can sometimes figure new ways to convert low- quality energy to high-quality energy. Improvements in wind turbines and photovoltaic cells allow us to convert low-quality light and wind to electricity.

47. Biological Systems and Thermodynamics  In accordance with the second law of thermodynamics, all organisms, including humans, are in the process of converting high-quality energy into low-quality energy. The process of releasing chemical-bond energy from food is known as cellular respiration (Produces heat) & is comparable to the process of combustion which is burning of fuel to obtain heat  Amount of energy in the universe is limited & only small portion of it is high quality.  An unfortunate consequence of E conversion is pollution.  Heat lost from E conversion is a pollutant.  If individuals use less E, there would be less waste heat & other forms of pollutions  When chemical-bond energy in food is converted into the energy needed to move, grow, or respond, waste heat is produced.

48. Pollution and Thermodynamics  A consequence of energy conversion is pollution. Wearing of brakes used to stop cars. Emissions from power plants.  If each person on Earth used less energy, there would be less waste heat and other forms of pollution that result from energy conversion.  The amount of energy in the universe is limited, and only a small portion of that energy is high- quality.

49. Summary  Science is a method of gathering and organizing information.  A hypothesis is a logical prediction about how things work that must account for all the known information and be testable.  If a hypothesis is continually supported by the addition of new facts, it may be incorporated into a theory.  A law is a broad statement that describes what happens in nature.

50. Summary  The fundamental unit of matter is the atom, which is made up of protons and neutrons in the nucleus surrounded by a cloud of moving electrons.  Chemical bonds are physical attractions between atoms resulting from the interaction of their electrons.  When chemical bonds are broken or formed, a chemical reaction occurs, and the amount of energy within the chemical bonds is changed.

51. Summary  Matter can occur in three states: solid, liquid, and gas.  Kinetic energy is the energy contained by moving objects; potential energy is the energy an object has because of its position.  The first law of thermodynamics states that the amount of energy in the universe is constant.  The second law of thermodynamics states that when energy is converted from one form to another, some of the useful energy is lost.