ENVIRONMENTAL SCIENCE 13e

CHAPTER 2:Science, Matter, and Energy

2-1 What Do Scientists Do?

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

Scientific Method HandoutPlease note this is a bit different than what is in your book

Identify question

Form testable hypothesis

Consult prior Collect data to test hypothesis If hypothesis is

knowledge rejected

Interpret results

Report for peer review

Publish findings

• How is the hypothesis different than the question?

• Why do we do the experiment?

The Scientific Process (3)

• Four features of the scientific process:– Curiosity

– Skepticism

– Peer review

– Reproducibility

Results of Science

– Scientific theories

– Scientific laws

Scientific Limitations

–Always some degree of uncertainty–Observational bias–Complex interactions, many variables

Mathematical models

Core Case Study: A Story about a Forest (1)

• Hubbard Brook Experimental Forest• Question: What is the environmental impact of forest

clear-cutting?• Controlled experiment – isolate variables

• Define – Control group: – Experimental group:Identify each for this experimentWhy do we need a control group?

Core Case Study: A Story about a Forest (2)

• Measure loss of water and nutrients

• Compare results– 30–40% increase in water runoff for which

group?– 6–8 times more nutrient loss for which group?

• Draw conclusions

Fig. 2-1, p. 23

Controlled field experiment. Note V-notched dams built at bottoms of two forested valleys so that all water and nutrients could be collected and measured. Then treesin second valley were cut.

Which is experimental site? Which is control?

Essay Questions on Exam 1

1. List the steps of the scientific method in order and provide a description of each step2. Discuss how the Hubbard Brook Experimental Forest exemplifies the scientific method in terms of first 4 steps

• Quickly write answer to question 1 and 2. Determine what was question, what was hypothesis, and what was done to test the hypothesis in this study (what were the 2 groups, what did they measure, for how long, what did they find out)

2-2 What Is Matter and How Do Physical and Chemical Changes Affect It?

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

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

What Is Matter?

• Matter – has mass and occupies space

• Element- fundamental substance that has a unique set of properties and cannot be broken down into simpler substances by chemical means ex. gold

• Compound- combinations of two or more elements held together in fixed proportions ex. H2O

– Atoms- smallest unit of matter into which an element can be divided and still have its characteristic chemical properties

– Ions- an atom or group of atoms with one or more net positive or negative charge

– Molecules- combination of 2 or more atoms of the same of different elements held together by forces called chemical bonds

Table 2-1, p. 29

For your reference

Supplement 6, Fig. 6, p. S28

Hydrochloricacid (HCl)

Gastric fluid(1.0–3.0)

Lemon juice,some acid rain

Vinegar, wine,beer, oranges

TomatoesBananas

Black coffeeBreadTypical rainwater

Urine (5.0–7.0)Milk (6.6)

Pure water

Blood (7.3–7.5)Egg white (8.0)

Seawater (7.8–8.3)Baking soda

100

10–1

10–2

10–3

10–4

10–5

10–6

10–7

10–8

10–9

10–10

10–11

10–12

10–13

10–14

01

7

8

9

12

13

14

6

10

11

3

4

5

2

Sodium hydroxide (NaOH)

Phosphate detergentsBleach, Tums

Soapy solutions,Milk of magnesia

Household ammonia(10.5–11.9)

Hair remover

Oven cleaner

pH is based on a log scale

Table 2-2, p. 29

For your reference

Table 2-3, p. 30

For your reference

Organic Compounds

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

Matter Quality

• Usefulness as a resource – Availability

– Concentration

• High quality

• Low quality

Aluminum ore

Low QualityHigh Quality

Solid

Salt

Coal

Gasoline

Aluminum can

Gas

Solution of salt in water

Coal-fired powerplant emissions

Automobile emissions

Fig. 2-5, p. 32

Changes in Matter

• Physical• Chemical• Law of Conservation of Matter

– Matter only changes from one form to another

– Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed

– See P. 32 Connections

Nuclear Changes (1)

• Radioactive decay – unstable isotopes– Alpha particles

– Beta particles

– Gamma rays

Nuclear Changes (2)

• Nuclear fission (type of rxn in nuclear power plant)

– Large mass isotopes split apart

– Chain reaction

• Nuclear fusion– Two light isotopes forced together

– High temperature to start reaction

– Stars

Fig. 2-6, p. 33

2-3 What Is Energy and How Do Physical and Chemical Changes Affect It?

• 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 converted from one form to another in a physical or chemical change, we end up with lower quality or less usable energy than we started with (second law of thermodynamics).

What Is Energy?

• Energy – the capacity to do work or transfer heat

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 (shorter wavelength, higher energy)

Energy Quality (1)

• High-quality energy – Concentrated, high capacity to do work

– High-temperature heat

– Nuclear fission

– Concentrated sunlight

– High-velocity wind

– Fossil fuels

Energy Quality (2)

• Low-quality energy– Dispersed

– Heat in atmosphere

– Heat in ocean

Laws of Thermodynamics

• First law of thermodynamics – Energy input = Energy output– Energy is neither created or destroyed– Energy only changes from one form to

another

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

Consequences of the Second Law of Thermodynamics

Why this is relevant to environmental science? • Automobiles

– ~13% moves car– ~87% dissipates as low-quality heat into the

environment• Incandescent light bulb

– ~5% useful light– ~95% heat

Solarenergy

Chemical energy(photo-

synthesis)

Mechanicalenergy

(moving,thinking, living)

Chemicalenergy(food)

Wasteheat

Wasteheat

Wasteheat

Wasteheat

Fig. 2-8, p. 36

Three Big Ideas of This Chapter

• There is no away (Think garbage or chemical disposal: It all goes somewhere. Just because we don’t see it anymore doesn’t mean it’s magically disappeared)

– Law of conservation of matter• You cannot get something for nothing (We can’t get more

energy out than we put in)– First law of thermodynamics (Law of conservation of

energy)• You cannot break even (whenever energy is converted from

one form to another in a physical or chemical change, we always end up with lower quality or less usable energy than we started with)– Second law of thermodynamics