Syllabus: Chemistry F1 Environmental Chemistry

The purpose of the course is to understand a number of environmental questions from the point of view of chemistry and physics. While some knowledge of math, physics and chemistry are useful it is not assumed.

The text for this course is Chemistry in Context Applying Chemistry to Society. The text was created as a project of the American Chemical Society. The goal of our study of the chemical aspects of the environment is to gain a qualitative understanding first and then, since chemistry is an quantitative, experimental science, to gain a quantitative understanding as well.

Although Chemistry in Context is used in this course, the course is not bound by the organization of the text.

Some questions:

  1. What is meant by "environment?"
  2. What is an ecosystem?
  3. How is biosphere defined?
  4. click here for some dictionary definitions.

  5. What are the over riding principles in environmental systems? Complex systems may be described by some principles ("the principles of ecology" for example-e.g. principles for a stable ecosystem.) On the other hand, the fundamentals are those of physics (forces) and chemistry. The question is: is it possible to get from the fundamentals of physics and chemistry to the principles governing complex systems? It has been, until recently, a proposition of science that from fundamental principles all else is derived. Chaos, the study of non-linear systems, changed all that. An example is the weather. Presumably, the worlds weather is governed by the fundamentals of physics and chemistry-the conservation of energy, the second law of thermodynamics, the hydrodynamic equations. But getting from these fundamentals to an accurate prediction of weather at a given location is either not possible, or at least remains elusive. How then are we to deal with complex ecological and environmental systems? It is one of the goals of our course to put this question in proper context.

  6. There is an environmental saying: "Think globally, act locally." This defines the major divisions of this course. We can illustrate part of the concept by considering one molecule, ozone. Ozone is a simple triatomic, reactive molecule formed from three oxygen atoms. It is a powerful oxidizing agent. For example, in the smog of Los Angeles a good test for ozone is to stretch a rubber band in the ground level atmosphere and measure the time taken for it to snap. Ozone reacts with the rubber polymer to weaken it's structure. Suppose we breath air containing ozone. It would be no surprise that this would be unhealthy. Therefore, ozone in the troposphere is bad for humanity at the street level. The question is, how bad and how much is bad? Where does this ozone come from? After chemical studies we now know that most of the photochemical oxidants, expressed as ozone, come from the reaction of hydrocarbons from automobiles, oxides of nitrogen from combustion and from sunlight. The way in which this works is fundamental chemistry.

    On the other hand, ozone is produced by the actinic rays of the sun in the stratosphere by a complex series of chemical reactions. This ozone has the property that it absorbs these actinic rays protecting the earth from them. Here ozone is a protector of humanity on a global scale. Where does this ozone come from? In the stratosphere ozone is produced by sunlight on a mixture of oxygen and water vapor. The way in which humankind has had an effect on global ozone is by the production of chloroflurocarbons, or CFC's. These chemicals are perfect for refrigeration and air conditioners. They are non-toxic and have the interesting property that when the gases expand their temperature is lowered. They have the unhappy property than when they diffuse into the upper atmosphere they enter into the ozone production reaction sequence and destroy it. This means that ultraviolet light can penetrate to the surface of the earth with undesirable consequences on human health and agriculture. So reduction of ozone in the stratosphere is not good while reduction of ozone locally is good.

    Here, the phrase "think globally act locally" has a more complicated twist. Acting locally in reduction of ozone in the troposphere means reducing nitrogen oxides and hydrocarbons predominantly from automotive sources while acting globally means reducing the use of CFC's.

Chapters from the text

  1. The Atmosphere
  2. Energy
  3. Water
  4. Better Living through Chemistry

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