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+

Elements Important to the Study of Environmental Science

Ions Important to the Study of Environmental Science

Brain break Stand up and turn to the person next to you: Discuss pH. How many more H ions are found in the next pH level? What is the average pH of rainwater?

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 = mc 2 ) 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

LecturePLUS Timberlake14 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 Isotopes of chlorine 35 Cl 37 Cl 1717 chlorine - 35 chlorine - 37 chlorine - 35 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 Isotopes disintegrate at predictable rates

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-238Half-life = 4.5 Billion Years K-40Half-life = 1.25 Billion Years C-14Half-life = 5, 730 Years Radioactive Isotopes 17

Radioactive Decay and Half Life The half-life of an element is the time it takes for half of the material you started with to decay. Each element has it’s own half-life Each element decays into a new element C 14 decays into N 14 while U 238 decays into Pb 206 (lead), etc. The half-life of each element is constant. It’s like a clock keeping perfect time. 18

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

Brain break Look at the person at your table across from you. If you are facing the windows, explain the first law of thermodynamics to your partner. If you are facing the board, explain the second law of thermodynamics.

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?

Inputs, Throughput, 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)

Fig. 2-4, p. 37 Nitrate (NO 3 – ) concentration (milligrams per liter) Undisturbed (control) watershed Disturbed (experimental) watershed Year