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
Good accuracy
and good precision
Poor accuracy
and poor precision
Poor accuracy
and good precision
Fig. 3.3, p. 46
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 CO2, the oceans will release
more dissolved CO2 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

Rate of metabolic
chemical reactions
Positive feedback loop
Heat in body
Heat input
from sun and
metabolism
Blood
temperature in
hypothalamus
Excess temperature
perceived by brain
Sweat production
by skin
Heat loss
from air
cooling skin
Negative feedback loop
Fig. 3.4, p. 51
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 C6H12O6

pH scale
pH – percent Hydronium
 Logarithmic scale from 0 (strong acid)
to 14 (strong base) with 7 being
neutral
 A 2 means 10-2 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
High Quality
Low Quality
Solid
Gas
Salt
Solution of salt in water
Coal
Coal-fired power
plant emissions
Gasoline
Automobile emissions
Fig. 3.9, p. 57
Aluminum can
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
Sun
High energy, short
wavelength
Low energy, long
wavelength
Nonionizing radiation
Ionizing radiation
Cosmic
rays
Gamma
rays
10-14
X rays
10-12
Visible
Far
Near
ultraviolet ultraviolet waves
waves
waves
10-8
10-7
10-6
Near
infrared
waves
10-5
Far
infrared
waves
microwaves
10-3
TV
waves
10-2 10-1
Radio
waves
1
Wavelength
in meters
(not to scale)
Fig. 3.10, p. 58
Physical vs chemical
changes
Reactant(s)
Products(s)
carbon + oxygen
carbon dioxide + energy
CO2 + energy
C + O2
O
C
O
C
O
+ energy
O
black solid
colorless gas
colorless gas
In-text, p. 59
Energy absorbed
solid
Melting
Evaporation
And boiling
Freezing
Condensation
liquid
Energy released
gas
Fig. 3.5, p. 54
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

Sheet
of paper
Block
of wood
Concrete
wall
Alpha
Beta
Gamma
Fig. 3.12, p. 62
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?

Fraction of original amount of
plutonium-239 left
1
1/2
1/4
1/8
1st
half-life
2nd
half-life
3rd
half-life
0
24,000
48,000
Time (years)
72,000
Fig. 3.13, p. 62
Ionizing Radiation
Harmful radiation resulting in two types
of damage
 Genetic damage – DNA mutations
 Somatic damage – tissue damage, ex.
Burns, cataracts, cancer, miscarriage

Other
1%
Ionizing radiation sources (US)
Consumer
products
3%
Radon
55%
Nuclear
medicine
4%
Medical
X rays
10%
Natural sources 82%
Human-generated 18%
Space
8%
The
human
body
11%
Earth
8%
Fig. 3.14, p. 63
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)

Fission fragment
n
n
n
Energy
n
Uranium-235
nucleus
Unstable
nucleus
Fission fragment
Fig. 3.15, p. 64
235
92 U
n
92
36 Kr
n
235
92 U
92
36 Kr
235
92 U
n
n
141
Ba
56
n
92 Kr
36
n
n
n
n
235
92 U
n
141
56 Ba
141
Ba
56
92 Kr
n
36
235
92 U
n
141
Ba
56
235
92 U
n
235
92 U
Fig. 3.16, p. 64
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”

Fuel
Reaction Conditions
Products
D-T Fusion
Neutron
+
Hydrogen-2 or
deuterium nucleus
+
+
+
100 million ˚C
Energy
+
+
Helium-4
nucleus
Hydrogen-3 or
tritium nucleus
D-D Fusion
+
+
+
Helium-3
nucleus
Hydrogen-2 or
deuterium nucleus
+
+
Energy
+
+
Proton
Neutron
Hydrogen-2 or
deuterium nucleus
1 billion ˚C
Neutron
Fig. 3.17, p. 64
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)
Second Law of Thermodynamics
(photosynthesis)
Waste
heat
Mechanical
energy
Chemical
energy
(food)
Chemical
energy
Solar
energy
Waste
heat
(moving,
thinking,
living)
Waste
heat
P.S. Also remember heat flows from hot to cold
Waste
heat
Fig. 3.18, p. 66
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!