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Chapter 2
Science Review
Bell Work
A hectare (ha) is a land measurement equal to 10,000
square meters. 1 acre=.40 ha
A web search of environmental organizations yielded a
range of estimates of the amount of forest clearing that is
occurring worldwide:
Estimate 1: 1 acre per second
Estimate 2: 80,000 acres per day
Estimate 32,000 ha per day
How can we convert these figures so that we can compare
them?
Objectives
Explain the fundamentals of Environmental
Chemistry and apply them to real world
situations
Differentiate between the types of energy and
explain energy flow
Explain the fundamentals of
Environmental Chemistry and
apply them to real world
situations
Understanding Chemistry provides a powerful tool
for understanding environmental science and
developing solutions to environmental problems
Atoms can form molecules and compounds, and
changes at the atomic level can result in alternate
forms of elements, such as ions and isotopes
Water facilitates the chemistry of life
Living things depend on organic compounds, which
are carbon-based
Reasons to understand
Chemistry for APES
Chemistry is crucial for understanding
How gases contribute to global climate change
How pollutants cause acid rain
The effects on health of wildlife and people
Water pollution
Wastewater treatment
Atmospheric ozone depletion
Energy Issues
Etc
pH and Solutions
What is pH?
pH stands for “Potential/Power of Hydrogen”
The negative logarithm of the concentration of
hydrogen ions in a solution
A high number = a very small concentration of H+ ions
in solution
A low number = a very high concentration of H+ ions in
solution
Logarithmic scale = each number on the scale
represents 10x more or less H+
Environmental
Science
Environmental
Science
Matter is
conserved
Law of conservation of matter
Matter can be transformed from one type of
substance into others, but it can neither be
created nor destroyed
Because the amount of matter stays constant
It is recycled in nutrient cycles and ecosystems
We need to consider the results of our actions,
especially in terms of pollution
Energy & Matter
Fixed amounts of each in the universe
Can be converted interchangeably (e = mc2)
Earth is an “open system” regarding energy
Earth is a “closed system” regarding matter
Energy & Mass Laws
1: Energy/Matter cannot be created or destroyed
2: Energy is always converted to “lower quality”
forms whenever work is done
Atomic Structure
The nucleus is tiny and very dense
The volume is almost entirely the electron cloud
Isotopes
Atoms with the same number of protons, but
different numbers of neutrons.
Atoms of the same element (same atomic
number) with different mass numbers
Isotopes of chlorine
35Cl
37Cl
17
17
chlorine - 35
LecturePLUS Timberlake
13
chlorine - 37
Types of Isotopes
Stable: the nucleus contains enough neutrons to
block the repulsive forces of the protons. This
keeps the isotope from breaking down over time.
2. Unstable: the nucleus of the atom does not have
right amount of neutrons to block the repulsive
forces of the protons; this makes the isotope
radioactive!
Radioactive Isotopes
Radioactive isotopes have unstable nuclei and
undergo nuclear decay (breakdown)
2. Nuclear decay involves the emission of energy
and/or particles from the nucleus in an attempt to
become more stable.
The energy/particles emitted from the nucleus are
termed radiation and can be alpha or beta particles and
gamma rays.
Isotopes disintegrate at predictable rates
Radioactive
Isotopes
Radioactive elements are unstable. They decay, and
change into different elements over time.
Not all elements are radioactive. Those that are listed
below are the most useful for geologic dating of fossils
are:
U-238
K-40
C-14
Half-life = 4.5 Billion Years
Half-life = 1.25 Billion Years
Half-life = 5, 730 Years
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Radioactive Decay and
Half Life
time it takes for half of the
The half-life of an element is the
material you started with to decay.
Each element has it’s own half-life
Each element decays into a new element
C14 decays into N14 while U238 decays into Pb206 (lead), etc.
The half-life of each element is constant. It’s like a clock
keeping perfect time.
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Nuclear Chemistry Review
Three types of
radiation
Alpha (He nucleus)
Beta (electrons)
Gamma (EMR wave)
Differences in
penetration
Alpha (sheet of paper)
Beta (block of wood)
Gamma (concrete wall)
Fission and Fusion
Fission
1 nucleus splits into
fragments (chain
reaction)
Ex. Nuclear reactor
Fusion
2 or more nuclei fuse
together
Ex. The Sun
Energy Laws
First Law
Energy cannot be created or
destroyed, only transformed or
converted between different
forms
Ex. Solar energy to chemical
energy during
Photosynthesis
During work, energy “in”
ALWAYS equals energy “out”
“You cannot get something for
nothing”
Second Law
During work, some energy is
degraded into lower quality
forms
High Quality (ex.
Electricity, Nuclear
Fission)
Medium Quality (ex.
Normal sunlight)
Low Quality (ex.
Geothermal heat)
You always end up with less
useable energy than you start
with
“You cannot break even”
The Second Law of
Thermodynamics in Living Systems
Electromagnetic
Spectrum
Environmental
“Science”
Some areas of ES research are experimental
and lab-based
Most research is field-based, involving the
study of highly complex FEEDBACK LOOPS
ES research is characterized by
A focus on CONNECTIONS & INTERACTIONS
LONG time periods
SYNERGISTIC connections
Types of Pollution
Degradable
Ex. Human sewage, organic matter
Persistent
Ex. DDT, certain plastics, laminates
Non-degradable
Ex. heavy metals, lead & mercury
Through-Put
Economies
High Through-Put Economy
High consumption of both matter and energy
Matter Recycling Economy
Reduced matter consumption
Still very high energy consumption
Low Through-Put Economy
Reduced matter and energy consumption
Is this possible to achieve?
and Outputs of an
Economic System
Experimental
Design
Problem
Question to be
answered
Hypothesis
Scientifically testable
statement
Independent or
Manipulated Variable
The one(s) being
tested or changed
Dependent or
Responding Variable
The one(s) being
measured
Control Group
No M.V. (for
comparison)
Constants
All other variables
influencing the
outcome
Precision vs.
Accuracy Accuracy
The nearness of a
measurement to an
agreed standard (ex. how
close to 1kg is a 1kg
standard weight on a
particular balance?)
Precision
The degree of
reproducibility and
consistency of a
measuring device
throughout multiple
measurements
The Effects of Deforestation on the
Loss of Water and Soil Nutrients
Core Case Study: Carrying Out a
Controlled Scientific Experiment
F. Herbert Bormann, Gene Likens, et al.:
Hubbard Brook Experimental Forest in NH (U.S.)
Compared the loss of water and nutrients from
an uncut forest (control site) with one that had
been stripped (experimental site)
Nitrate (NO3– ) concentration
(milligrams per liter)
60
40
20
1963
Undisturbed
(control)
watershed
1964
1965
Disturbed
(experimental)
watershed
1966
1967
Year
1968
1969
1970
1971
1972
Fig. 2-4, p. 37