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!