{chem 180} class notes.pdf - Midterm 1 January 6 2019 Part...

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Midterm 1 January 6, 2019 Part 1 - Intro to Chemistry of the Environment and Air Introduction/Risks COMMON TRENDS DIVERT US FROM EATING CERTAIN FOODS AND DOING CERTAIN THINGS: Fish contain mercury and PCBs, hamburgers contain dioxins, the buns are contaminated with acrylamide, corn is GMO, etc. Statistics apply to populations, not individual people. The presence of a chemical does not imply the presence of a risk. Small numbers does not mean small risk. Children are NOT small adults. Things are also dependent on what they are; i.e. dogs cannot eat chocolate but humans can. CORRELATION DOES NOT MEAN CAUSATION!! Hazard vs. Risk The risk can be altered and/or reduced, but the hazard cannot. Hazard: something dangerous. Risk: level of exposure to danger. Risk = Toxicity x Exposure Avoiding Risks - (i.e.) The Flu; wash hands, get a flu shot - More effective to wash our hands with water than it is to use disinfectants. - The alcohol in them invigorates the germs and handwashing washes them away. - (i.e.) Measles; getting the vaccine works, even though vaccination is controversial. - (i.e.) Vending Machines killing people - While the risk is very small, there are people severely injured or killed by them. - THERE ARE RISKS FOR LITERALLY EVERYTHING WE DO!! Chemical Understanding Chemicals are to be understood, this will aid in understanding the risks. There are over 130 million known chemicals and form the basis of our lives, and 99.9% of them are naturally occuring. Natural, however, does not mean it’s safe. For example, bacteria, poison from animals, some plants, are all naturally occurring but can be very harmful. “Synthetic“ does not mean that something is ‘dangerous’. For example, aspirin is synthetic but it is not dangerous in the proper amount. Air History - In Classical times used to be seen as a single solitary element. - Element comes from Greek word stoicheion, where stoichiometry comes from.
- Some people believed in a single eternal substance that separated and created different elements that had their own shapes and qualities. The Atmosphere Air is a mixture and the atmosphere is very thin. It exists from sea level to about 100s of Km above the earth. A.k.a. The “Thin Blue Line”. The atmosphere provides us with the ingredients for necessary life and serves a protective role in climate moderation and radiation absorption. The area of the place compared to the atmosphere is the determinant of where we can live. On average, most humans live within the first 2100 m of the atmosphere from sea level. Gas Pressure: force exerted from the collisions of gas molecules against an object. The mass of the atmosphere is 5.1 x 10^18 Kg and the surface area is 5.q x 10^14 m^2. There is 1 Kg of matter above every 1cm^2 of area on the Earth.

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