Chapter 2 Systems

Easter Island  A closed system  Once a paradise  Tragedy of the commons  Time delay  Exponential devastation  Population crash  Model of the planet

Experiments  Blind – do not know what is being taken by subject  Double blind – neither the tester nor the subject know what is being given to the subject  Placebo – harmless sample used as a control and test validity of the group being used

Accuracy vs. Precision  Accuracy refers to getting the correct measurement or reading  Precision refers to being able to repeat your performance exactly

Fig. 3.3, p. 46 Good accuracy and good precision Poor accuracy and poor precision Poor accuracy and good precision

Positive feedback loop  Runaway cycle  A change in the system (input) causes the output to increase which causes more input  Ex. Global warming – as temperatures rise from increased CO 2, the oceans will release more dissolved CO 2 causing the ocean temperatures to rise further.

Negative feedback loop  Homeostasis  A change in input creates an output which causes the input to decrease  Ex. As pollution becomes less of a problem, it will bother fewer people, regulations on pollution will become less stringent

Fig. 3.4, p. 51 Rate of metabolic chemical reactions Heat input from sun and metabolism Heat loss from air cooling skin Heat in body Positive feedback loop Blood temperature in hypothalamus Excess temperature perceived by brain Sweat production by skin Negative feedback loop

Time delays in systems  Typical for environmental systems  Do not see/feel the consequence coming until it is too late to avoid  Smoking – years of smoking may lead to cancer and then quitting doesn’t matter, it is too late.

Synergistic interactions  When two processes create a stronger effect together than the sum of their individual parts  Ex. Smog – heat and UV radiation from the sun combine with car emissions and create a toxic substance worse than either alone

What’s the “matter”  Matter – anything with mass and volume  Elements vs. compounds  Parts of the atom, atomic number, mass number  Ions – positive or negative  Isotopes – watch those neutrons  Molecules – types of bonding ionic, covalent, hydrogen

Organic compounds (have carbon)  NOT Carbon Dioxide (exception)  Hydrocarbons – fossil fuels (methane)  Chlorinated hydrocarbons – DDT  Chlorofluorocarbons (CFCs) – Freon  Carbohydrates – glucose C 6 H 12 O 6

pH scale  pH – percent Hydronium  Logarithmic scale from 0 (strong acid) to 14 (strong base) with 7 being neutral  A 2 means Hydronium ions in solution or ten times more than a 3 on the scale

Fig. 3.7, p. 56

Quality matter  High quality matter is easily used by man in terms of creating a product  Low quality matter is difficult to obtain or to convert into usable objects

Fig. 3.9, p. 57 High Quality Solid Salt Coal Gasoline Aluminum can Low Quality Gas Solution of salt in water Coal-fired power plant emissions Automobile emissions Aluminum ore

Human matter  What are we made of? The human body contains about 100 trillion cells. There is a nucleus inside each human cell (except red blood cells). Each nucleus contains 46 chromosomes, arranged in 23 pairs. One chromosome of every pair is from each parent. The chromosomes are filled with tightly coiled strands of DNA. Genes are segments of DNA that contain instructions to make proteins—the building blocks of life. There are approximately 140,000 genes in each cell, each coded by sequences of nucleotides in its DNA molecules.

Forms of energy  Energy is the ability to do work and transfer heat  Kinetic energy – motion  Potential energy – stored energy  High quality is easy to use to do work, such as electricity

Fig. 3.10, p. 58 Sun High energy, short wavelength Low energy, long wavelength Ionizing radiation Nonionizing radiation Cosmic rays Gamma rays X rays Far ultraviolet waves Near ultraviolet waves Visible waves Near infrared waves Far infrared waves microwaves TV waves Radio waves Wavelength in meters (not to scale)

Physical vs chemical changes In-text, p. 59 Reactant(s) carbon + oxygen C + O 2 CO 2 + energy carbon dioxide + energy + energy Products(s) black solidcolorless gas C O O OOC

Fig. 3.5, p. 54 Energy absorbed Melting Freezing Evaporation And boiling Condensation solidliquidgas Energy released

Law of conservation of matter  There is “no away”  – matter is changed either physically or chemically, but is still present  We will never run out of matter, only matter in an easily used form

The breakdown of matter  Concentration  Persistence – how long will it last?  Degradable – via physical,chemical, or biological  Slowly degradable – (plastics, DDT (takes decades))  Nondegradable (elements like lead, mercury)

Nuclear (not nucular) Changes  Radioactive change (decay) is another possible change to matter  Natural radioactive decay  Nuclear fusion  Nuclear fission

Natural radioactive decay  Unstable isotopes (radioisotopes) breakdown at a uniform rate known as its half life  Gives off Gamma rays (ionizing radiation) in the form of alpha (2 protons and 2 neutrons) and beta (electrons) particles  Radioactivity is measured in Curies

Fig. 3.12, p. 62 Sheet of paper Block of wood Concrete wall Alpha Beta Gamma

Don’t eat that, it’s radioactive  In general it takes ten half lives for a radioactive substance to be considered safe.  Plutonium-239 is carcinogenic is minute amounts. If its half-life is 24,000 years, how long do you have to quarantine a sample until it is safe?

Fig. 3.13, p. 62 Fraction of original amount of plutonium-239 left 1 1/2 1/4 1/8 0 24,00048,00072,000 Time (years) 1st half-life 2nd half-life 3rd half-life

Ionizing Radiation  Harmful radiation resulting in two types of damage  Genetic damage – DNA mutations  Somatic damage – tissue damage, ex. Burns, cataracts, cancer, miscarriage

Fig. 3.14, p. 63 Radon 55% Other 1% Consumer products 3% Nuclear medicine 4% Medical X rays 10% The human body 11% Earth 8% Space 8% Natural sources 82% Human-generated 18% Ionizing radiation sources (US)

Fission vs. Fusion  Nuclear fission involves splitting atoms  Typically a large mass isotope (U235)  When neutrons are shot at nucleus, the nucleus splits releasing energy, and more neutrons  Creates chain reaction  Used in power generation (Nuclear power plants)

Fig. 3.15, p. 64 Fission fragment Energy n n n n Uranium-235 nucleus Unstable nucleus

Fig. 3.16, p. 64 n U Kr Ba n n n Kr U U Ba Kr Ba Kr Ba n n n n n n n n U U U U n

Fusion is “Da Bomb”  Two light nuclei are slammed together at high speed  Fusing produces new nucleus and releases energy  Typically isotopes of hydrogen are used  This is what is inside a Hydrogen Bomb, like “Fatman and Little Boy”

Fig. 3.17, p. 64 FuelReaction ConditionsProducts D-T Fusion Hydrogen-2 or deuterium nucleus Hydrogen-3 or tritium nucleus Hydrogen-2 or deuterium nucleus Hydrogen-2 or deuterium nucleus D-D Fusion Neutron Energy ++ Helium-4 nucleus ++ Helium-3 nucleus Energy Neutron million ˚C 1 billion ˚C Neutron Proton +

First Law of Thermodynamics  Also called the law of conservation of energy  Energy is neither created nor destroyed but may be converted from one form into another  ENERGY IN = ENERGY OUT

Second Law of Thermodynamics  When energy changes form, some energy is degraded in lower quality energy  In other words, heat is lost to the surrounding environment in all energy conversions or transfers (entropy)

Fig. 3.18, p. 66 Solar energy Waste heat Chemical energy (photosynthesis) Waste heat Waste heat Waste heat Chemical energy (food) Mechanical energy (moving, thinking, living) Second Law of Thermodynamics P.S. Also remember heat flows from hot to cold

How does the second law of energy affect life?  If “all” energy comes from the sun, explain why, in terms of the environment, it is better to be a vegetarian than to be a carnivore.

The End… finally!