Chapter 2 Systems Easter Island A closed system Once a paradise Tragedy of the commons Time...
-
Upload
dale-walsh -
Category
Documents
-
view
215 -
download
2
Transcript of Chapter 2 Systems Easter Island A closed system Once a paradise Tragedy of the commons Time...
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 accuracyand poor precision
Poor accuracyand 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 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
Fig. 3.4, p. 51
Rate of metabolicchemical reactions
Heat inputfrom sun andmetabolism Heat loss
from aircooling skin
Heat in body
Positive feedback loop
Bloodtemperature inhypothalamus
Excess temperatureperceived by brain
Sweat productionby 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 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
Fig. 3.9, p. 57
High Quality
Solid
Salt
Coal
Gasoline
Aluminum can
Low Quality
Gas
Solution of salt in water
Coal-fired powerplant emissions
Automobile emissions
Aluminum ore
Human matter What are we made of?
Thehumanbody
containsabout 100
trillioncells.
There is anucleusinsideeach
human cell(except redblood cells).
Eachnucleus
contains 46chromosomes,
arrangedin 23pairs.
Onechromosome
of everypair
is fromeach
parent.
Thechromosomes
are filledwith tightly
coiledstrandsof 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, shortwavelength
Low energy, longwavelength
Ionizing radiation Nonionizing radiation
Cosmicrays
Gammarays
X rays Farultraviolet
waves
Nearultraviolet
waves
Visiblewaves
Nearinfraredwaves
Farinfraredwaves
microwaves TVwaves
Radiowaves
Wavelengthin meters(not to scale)
10-14 10-12 10-8 10-7 10-6 10-5 10-3 10-2 10-1 1
Physical vs chemical changes
In-text, p. 59
Reactant(s)
carbon + oxygen
C + O2CO2 + energy
carbon dioxide + energy
+ energy
Products(s)
black solid colorless gas colorless gas
C
O
OO OC
Fig. 3.5, p. 54
Energy absorbed
Melting
Freezing
EvaporationAnd boiling
Condensation
solid liquid gas
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
Concretewall
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
Fra
ctio
n o
f o
rig
inal
am
ou
nt
of
plu
ton
ium
-239
left
1
1/2
1/4
1/8
024,000 48,000 72,000
Time (years)
1sthalf-life
2ndhalf-life
3rdhalf-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
Radon55%
Other1%
Consumerproducts
3%
Nuclearmedicine
4%
MedicalX rays10%
Thehumanbody11%
Earth8%
Space8%
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
Fission fragment
Energy
n n
n
n
Uranium-235nucleus
Unstablenucleus
Fig. 3.16, p. 64
n
U23592
9236 Kr
Ba14156
n
n
n
9236 Kr
U23592
U23592
Ba14156
9236
Kr
Ba14156
9236
Kr
Ba14156
n
n
n
n
n
n
n
n
U23592
U23592
U23592
U23592
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
Fuel Reaction Conditions Products
D-T Fusion
Hydrogen-2 ordeuterium nucleus
Hydrogen-3 ortritium nucleus
Hydrogen-2 ordeuterium nucleus
Hydrogen-2 ordeuterium nucleus
D-D Fusion
+
+
+
+
Neutron
Energy
+ +
Helium-4nucleus
+ +
Helium-3nucleus
Energy
Neutron
++
+ +
100 million ˚C
1 billion ˚CNeutron
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
Solarenergy
Wasteheat
Chemicalenergy
(photosynthesis)
Wasteheat
Wasteheat
Wasteheat
Chemicalenergy(food)
Mechanicalenergy(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!