Science, Matter, and Energy

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Science, Matter, and Energy

• Chapter 2

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Science Focus Easter Island

• Solving a mystery
• Population crash cause and effect
• Evolving hypotheses
• Unsustainable resource use?
• Rats?
• Disease?
• Science as a process

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2-1 What Is Science?

• Concept 2-1 Scientists collect data and develop
  theories, models, and laws about how nature works.

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Science

• Search for order in nature
• Observe behavior
• Attempt to quantify cause and effect
• Make predictions

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The Scientific Process (1)

• Identify problem/question
• Design experiments
• Collect data
• Formulate hypothesis

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The Scientific Process (2)

• Develop models
• Propose theories
• Derive natural laws

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What Scientists Do
Fig. 2-2
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Propose an hypothesis to explain data
Use hypothesis to make testable predictions
Perform an experiment to test predictions
Make testable predictions
Accept hypothesis
Revise hypothesis
Test predictions
Scientific theory Well-tested and widely
accepted hypothesis
Fig. 2-2
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Identify a problem
Stepped Art
Fig. 2-2
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Results of Science

• Goals
• Scientific theories
• Scientific laws
• Degree of certainty and general acceptance
• Frontier science
• Reliable science
• Unreliable science

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Scientific Limitations

• Limitations 100 certain?
• Absolute proof versus probability
• Observational bias
• Complex interactions, many variables
• Estimates and extrapolating numbers
• Science does not answer moral or ethical questions

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2-2 What Is Matter?

• Concept 2-2A Matter consists of elements and
  compounds, which are in turn made up of atoms,
  ions, or molecules.

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What Is Matter?

• Matter has mass and occupies space
• Elements and Compounds
• Atoms
• Ions
• Molecules

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Elements Important to the Study of Environmental
Science
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Building Blocks of Matter (1)

• Atomic Theory elements made from atoms
• Atoms
• Protons positive charge
• Neutrons uncharged
• Electrons negative charge

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Building Blocks of Matter (2)

• Atomic number
• Number of protons
• Mass number
• Neutrons protons
• Isotopes
• Same atomic number, different mass

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Building Blocks of Matter (3)

• Ions
• One or more net positive or negative electrical
  charges
• Chemical formula
• Number and type of each atom or ion
• Compounds
• Organic
• Inorganic

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Ions and Compounds Important to the Study of
Environmental Science
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Ions and Compounds Important to the Study of
Environmental Science
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Organic Compounds

• Carbon-based compounds
• Examples
• Hydrocarbons
• Chlorinated hydrocarbons
• Simple carbohydrates
• Complex carbohydrates
• Proteins
• Nucleic acids (DNA and RNA)

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Matter Quality

• Usefulness as a resource
• Availability
• Concentration
• High quality
• Low quality

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Examples of Matter Quality
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Low Quality
High Quality
Solid
Gas
Salt
Solution of salt in water
Coal
Coal-fired power plant emissions
Gasoline
Automobile emissions
Aluminum ore
Aluminum can
Fig. 2-5
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How Can Matter Change?

• Concept 2-2B When matter undergoes a physical or
  chemical change, no atoms are created or
  destroyed (the law of conservation of matter).

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Changes in Matter

• Physical
• Chemical

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Reactant(s)
Product(s)
Energy
Carbon dioxide
Carbon Oxygen

C
O2
Energy
CO2
Energy

Black solid
Colorless gas
Colorless gas
p. 34
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Nuclear Changes (1)

• Radioactive decay unstable isotopes
• Alpha particles
• Beta particles
• Gamma rays

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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

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Types of Nuclear Changes
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Radioactive decay
Radioactive decay occurs when nuclei of unstable
isotopes spontaneously emit fast-moving chunks of
matter (alpha particles or beta particles),
high-energy radiation (gamma rays), or both at a
fixed rate. A particular radioactive isotope may
emit any one or a combination of the three items
shown in the diagram.
Alpha particle (helium-4 nucleus)
Radioactive isotope
Gamma rays
Beta particle (electron)
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Nuclear fission
Uranium-235
Nuclear fission occurs when the nuclei of certain
isotopes with large mass numbers (such as
uranium-235) are split apart into lighter nuclei
when struck by a neutron and release energy plus
two or three more neutrons. Each neutron can
trigger an additional fission reaction and lead
to a chain reaction, which releases an enormous
amount of energy.
Fission fragment
Energy
Neutron
Energy
Energy
Uranium-235
Fission fragment
Energy
Fig. 2-7
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Nuclear fusion
Reaction conditions
Fuel
Products
Helium-4 nucleus
Proton
Neutron
Hydrogen-2 (deuterium nucleus)
Nuclear fusion occurs when two isotopes of light
elements, such as hydrogen, are forced together
at extremely high temperatures until they fuse to
form a heavier nucleus and release a tremendous
amount of energy.
100 million C
Energy
Hydrogen-3 (tritium nucleus)
Neutron
Fig. 2-7
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Law of Conservation of Matter

• Matter only changes from one form to another
• There is no throwing away
• Environmental implications
• Recycle
• Reuse
• Must deal with wastes and pollutants

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2-3 What Is Energy and How Can It Change Its Form?

• 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 changed from one
  form to another, we end up with lower quality or
  less usable energy than we started with (second
  law of thermodynamics).

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What Is Energy?

• Energy the capacity to do work or transfer heat

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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

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Electromagnetic Radiation
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Energy Quality

• High-quality energy concentrated
• High temperature heat
• Nuclear fission
• Concentrated sunlight
• High-velocity wind
• Fossil fuels
• Low-quality energy dispersed
• Heat in atmosphere and ocean

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Laws of Conservation of Energy (Thermodynamics)

• First law of thermodynamics
• Energy input Energy output
• Second law of thermodynamics
• Energy use results in lower-quality energy
• Dispersed heat loss

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Consequences of the Second Law of Thermodynamics
(1)

• Automobiles
• 6 moves car
• 94 dissipates as low-quality heat into the
  environment
• Incandescent light bulb
• 5 useful light
• 95 heat

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Consequences of the Second Law of Thermodynamics
(2)

• Living systems
• Energy lost with every conversion

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Second Law of Thermodynamics and Its Effect on
Living Systems
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2-4 How Can We Use Matter and Energy More
Sustainably?

• Concept 2-4A The processes of life must conform
  to the law of conservation of matter and the two
  laws of thermodynamics.
• Concept 2-4B We can live more sustainably by
  using and wasting less matter and energy,
  recycling and reusing most matter resources, and
  controlling human population growth.

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High-throughput (High-waste) Economy

• Increase flow of matter and energy to boost
  economy
• Environmental capacity?

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High-throughput Economy
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Inputs (from environment)
System throughputs
Outputs (into environment)
Low-quality energy (heat)
High-quality energy
High-waste economy
Waste and pollution
High-quality matter
Fig. 2-12
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Low-throughput (Low-waste) Economy

• Matter recycling and reuse economy
• Mimic nature
• Maximize matter cycling with minimal energy input

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Low-throughput Economy
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Outputs (into environment)
System throughputs
Inputs (from environment)
Energy conservation
Low-quality energy (heat)
High-quality energy
Low-waste economy
Waste and pollution prevention
Pollution control
Waste and pollution
High-quality matter
Recycle and reuse
Fig. 2-13