SCIENCE, TECHNOLOGY, AND ENVIRONMENTAL SCIENCE. Environmental science is the study of how we and other species interact with one another and with the nonliving environment of matter and energy. Technology is the creation of new products and processes that are supposed to improve our chances for survival, our comfort level, and our quality of life. Scientific Hypothesis: an educated guess that explains a scientific law or certain scientific facts. It becomes a scientific theory; a well-tested and widely accepted scientific hypothesis. The ways scientists gather data and formulate and test scientific hypotheses, laws, and theories are called scientific methods. MATTER: FORMS, STRUCTURE, AND QUALITY Matter is anything that has mass (the amount of material in an object) and takes up space. Matter is found in 3 chemical forms: elements (building blocks of matter), compounds (two or more different elements held together in set proportions by attractive forces called chemical bonds), and mixtures (combinations of elements, compounds, or both). The three types of building blocks are atoms (the smallest unit of matter that is unique to a particular element), ions (electrically charged atoms), and molecules (combinations of atoms). Matter is also found in three physical states: solid, liquid, and gas. Solids having the most orderly arrangement of atoms or molecules and gases the least orderly. The main building blocks of an atom are positively charged protons (represented by the symbol p), uncharged neutrons (n), and negatively charged electrons (e). the center of an atom is called the nucleus which contains the protons and neutrons. The atomic number (number of protons) is what distinguishes each individual element. The mass number is the number of neutrons and protons in the nucleus. All atoms of an element have the same number of protons in their nuclei, they may have different numbers of neutrons in their nuclei and thus different mass numbers. These different forms of an element with the same atomic number but a different mass number are called isotopes. Most matter exists as compounds. We use a shorthand chemical formula to show the number of atoms (or ions) of each element found in a compound. Organic compounds contain atoms of carbon, usually combined with each other and with atoms of other elements such as hydrogen, oxygen, nitrogen and others. Hydrocarbons are compounds of carbon and hydrogen atoms. An example is methane (CH4), the main component of natural gas. Chlorofluorocarbons (CFCs) are compounds of carbon, chlorine, and fluorine atoms. An example is Freon-12 (ClCl2F2), used as a coolant in refrigerators and air conditioners, as an aerosol propellant, and as a foaming agent for making some plastics. Simple carbohydrates (simple sugars) are compounds of carbon, hydrogen, and oxygen atoms. An example is glucose (C6H12O6). Larger and more complex organic compounds, called polymers, consist of a number of massive structural or molecular units (monomers) linked together by chemical bonds. All other compounds are called inorganic compounds. Classifying compounds as organic or inorganic is somewhat arbitrary. All organic compounds contain one or more carbon atoms, but CO and CO2 are classified as inorganic compounds. Matter quality is a measure of how useful a matter resource is, based on its availability and concentration. High-quality matter is organized and concentrated, and is usually found near the earthís surface. It has great potential for use as a resource. Low-quality matter is disorganized, dilute, or dispersed in the ocean or the atmosphere. It usually has little potential for use as a matter resource. Entropy is a measure of the disorder or randomness of a system. The greater its order, the lower its entropy. Thus an aluminum can has a lower entropy than aluminum ore. ENERGY: TYPES, FORMS, AND QUALITY Energy is the capacity to do work. Kinetic energy is the energy that matter has because of its motion and mass. Heat is the total kinetic energy of all the randomly moving atoms, ions, or molecules within a given substance, excluding the overall motion of the whole object. Temperature is a measure of the average speed of motion of the atoms, ions, or molecules in a sample of matter at a given moment. For example the total heat content of a lake is enormous, but its average temperature is low. Potential energy is stored energy that is potentially available for use. Potential energy can become kinetic energy. For example: a rocks potential energy becomes kinetic energy as it falls from a cliff. Various types of energy are converted to other types of energy for example: an electric power plant burns some kind of fuel (oil, gas, coal...) to make heat, to boil water, to make steam which flows through turbines (thermal energy is converted into kinetic energy). The turbines turn generators to make electricity. When you turn on a light you are at the end of the following energy chain: fuel to heat to steam to kinetic energy to electricity. Electromagnetic Radiation is radiant energy traveling as waves such as Radio waves, TV waves, microwaves, infrared radiation, visible light (colors we see), ultraviolet radiation, X rays, gamma rays, and cosmic rays. Some 99% of the energy used to heat Earth and all our buildings comes directly from the sun. Solar energy includes both perpetual direct energy from the sun and several forms of energy produced indirectly by the sunís energy. These include wind, falling and flowing water (hydropower), and biomass (solar energy converted to chemical energy stored in organic compounds in trees and plants). We use wind turbines and hydroelectric power plants to convert the indirect solar energy of wind and falling or flowing water into electricity. Solar cells convert solar energy directly into electricity. Energy quality measures usefulness. High-quality energy (low entropy) is organized or concentrated and has great ability to perform useful work for example electricity, coal, and gasoline. Low-quality energy (high entropy) is disorganized or dispersed and has little ability to do useful work. An example is the Atlantic Ocean. PHYSICAL AND CHEMICAL CHANGES & THE LAW OF CONSERVATION OF MATTER A physical change involves no change in chemical composition. For example, when ice melts or liquid water is boiled, none of the H20 molecules involved are altered. In a chemical change or chemical reaction, there is a change in the chemical composition. A chemical equation shows the chemical formulas for the reactants (starting chemicals) and the products (chemical produced) with an arrow. C + O2 ---------> C02 + ENERGY reactants products The reaction shows how the burning of coal or any carbon-containing compounds, such as those in wood, natural gas, oil and gasoline, adds carbon dioxide gas to the atmosphere yet are a useful energy source. Earth loses some gaseous molecules to space, and it gains small amounts of matter from space, mostly in the form of occasional meteorites and cosmic dust. Earth has essentially all the matter it will ever have. The Law of Conservation of Matter states that we canít create nor destroy matter. All we can do is rearrange matter into different spatial patterns (physical changes) or different combinations (chemical changes). We can remove substances from polluted water at a sewage treatment plant, but the sludge must either be burned (producing air pollution), buried (contaminating underground water), or cleaned up and applied to the land as fertilizer (dangerous if the sludge contains non-degradable toxic metals, such as lead and mercury). NUCLEAR CHANGES In addition to physical and chemical changes, matter can undergo a third type of change, known as a nuclear change. The law of conservation of matter and energy: In any nuclear change the total amount of matter and energy involved remains the same. Natural radioactive decay is a nuclear change in which unstable isotopes spontaneously shoot out fast-moving particles, high-energy radiation, or both at a fixed rate. It continues until the original isotope is changed into a new stable nonradioactive isotope. The unstable isotopes are called radioactive isotopes, or radioisotopes. This rate of decay is expressed in terms of half-life-the time needed for one-half of the nuclei in a radioisotope to become another more stable substance. Each radioisotope has a characteristic half-life, which may range from a few millionths of a second to several billion years. An isotopeís half-life cannot be changed. Thatís why radioactive dating is so reliable in determining the age of rocks, bones, and fossils. Half-life can also be used to estimate how long a sample of a radioisotope must be stored in a safe enclosure before it decays to a safe level. A general rule of thumb is that this takes about ten half-lives. Thus people would have to be protected from radioactive waste containing iodine-131 (which concentrates in the thyroid gland) for 80 days (10 x 8 days). Plutonium-239, which is produced in nuclear reactors and can cause lung cancer when inhaled in tiny amounts, must be stored safely for 240,000 years (10 x 24,000 years). Radiation emitted by radioisotopes is damaging ionizing radiation. The most common form of ionizing energy are gamma rays. High-speed particles emitted from the nuclei are different from ionizing radiation. The two most common types of ionizing particles emitted by radioactive isotopes are alpha particles (fast-moving, positively charged chunks of matter that consist of two protons and two neutrons) and beta particles (high-speed electrons). We are all exposed to small amounts of harmful ionizing radiation from both natural and human sources. Nuclear fission is a nuclear reaction in which nuclei of certain isotopes with large mass numbers are split apart when struck by neutrons; each fission releases two or three more neutrons + energy. Each of these neutrons can cause an additional fission. Multiple fissions within a critical mass forms a chain reaction, which releases an enormous amount of energy. In a nuclear reactor, the nuclear fission chain reaction is controlled. In nuclear fission reactors nuclei of uranium-235 are split and heat is released. The heat is used to produce high-pressure steam, which spins turbines, which generates electricity. Nuclear fusion is a nuclear reaction in which two isotopes of light elements, such as hydrogen, are forced together at extremely high temperatures until they fuse to form a heavier nucleus, releasing energy in the process. Fusion of hydrogen to form helium is the source of energy in stars. After World War II the principle of uncontrolled nuclear fusion was used to develop H-bombs, or thermonuclear weapons. Scientists have tried to develop controlled nuclear fusion, however, this process is still at the laboratory stage. The First and Second Laws of Energy (Thermodynamics) The law of conservation of energy is also known as the first law of energy or first law of thermodynamics. This law means when one form of energy is converted to another form energy input always equals energy output: The second law of energy or the second law of thermodynamics (law of entropy): When energy is changed from one form to another, some of the useful energy is always changed to lower-quality, more dispersed (higher entropy), less useful energy. This degraded energy is usually in the form of heat. In a car, only about 10% of the high-quality energy of gasoline is used to move the car and run its electrical systems. In an incandescent light bulb, only about 5% becomes useful light the rest is wasted heat. Because of the second energy law, the more energy we use (and waste), the more disorder (entropy) we create in the environment. ENERGY EFFICIENCY AND NET USEFUL ENERGY In the United States, 84% of all commercial energy used is wasted. About 41% of this energy is wasted automatically because of the degradation of energy quality. However, about 43% is wasted unnecessarily mostly by using fuel-wasting motor vehicles, furnaces, and other devices and by living and working in leaky, poorly insulated buildings. Americans waste as much energy as two-thirds of the worldís population consumes. Much of this unnecessary energy waste can be eliminated by increasing the energy efficiency. Energy efficiency is the percentage of total energy input that does useful work. Some energy efficient devices may cost more initially but in the long run they save money by having lower life cycle cost: initial cost plus lifetime operating costs. For example, the sequence of energy-using and energy-wasting steps involved in using electricity produced from fossil fuels is extraction--- transportation--- processing--- transportation to power plant--- electric generation--- transmission--- end use. Using high-quality electrical energy to provide low-quality heating for living space or household water is like using a chain saw to cut butter or a sledgehammer to kill a fly. In 1991 the average price of obtaining 250,000 kilocalories (1 million BTUs) for heating space or water in the United States was $6.05 using natural gas, $7.56 using kerosene, $9.30 using oil, $9.74 using propane, and $24.15 using electricity. Energy efficiency of some common devices: Human body: 20-25% Fluorescent light: 22% Car 10% Incandescent light 5% The 3 least efficient energy-using devices in use today are (1) incandescent light bulbs, (2) vehicles with internal combustion engines, and (3) nuclear power plants producing electricity for heating (which wastes 86% of the energy in their nuclear fuel). USING WASTE HEAT A special way to use waste heat produced by industrial plants is cogeneration, the production of two useful forms of energy such as steam and electricity from the same fuel source. For example: Natural gas is used to boil water for an industrial plant. The excess steam or heat can be used to make electricity that the plant could also use or even sell to another buyer. MATTER AND ENERGY LAWS AND ENVIRONMENTAL PROBLEMS THROWAWAY SOCIETIES Most advanced industrialized countries are throwaway societies, sustaining continued economic growth by increasing the flow of materials and energy, through the economy, to sinks (air, water, soil, organisms) where pollutants and wastes end up. MATTER-RECYCLING SOCIETIES A stopgap solution to a throwaway society is to convert to a matter-recycling society. Recycling resources always requires high-quality energy, which cannot be recycled. Also, there is a physical limit to the number of times some materials, such as paper fiber, can be recycled. Shifting from a throwaway society to a matter-recycling society is only a temporary solution. Experts argue over how close we are to environmental overload, but the scientific law of matter and energy indicated that limits do exist. The best long-term solution is to shift from a society based on maximizing matter and energy flow (throughput) to a Sustainable-Earth society: ∑ Reduce to prevent depletion and of planetary sources. ∑ Use energy more efficiently. ∑ Shift from exhaustible to less harmful perpetual and renewable energy. ∑ Not waste potentially renewable resources, and use them no faster than the rate at which they are regenerated. ∑ Not waste nonrenewable resources. ∑ Recycle and reuse at least 80% of the matter we now discard as trash. ∑ Make things that last longer and are easier to recycle, reuse, and repair ∑ Emphasize pollution prevention and waste reduction instead of pollution cleanup and waste management. ∑ Stop human population growth.
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