Kotz and Triechel, Chemistry and Chemical Reactivity Chapter 20: Sections 1-7.
- 20.1 Chemical analysis of the atmosphere in different locations and layers is critical to understanding the composition and exchanges within regions. Most of the atmosphere is nitrogen at 78%; oxygen accounts for 21%, and argon for most of the rest. Carbon dioxide accounts for less than 0.5%...but is arguably the most controversial and critical component, since even small changes in this small amount can influence temperature. Nitrogen and nitrous oxides, oxygen in several forms, carbon dioxide, and methane all move from the atmosphere to living organisms through complex cycles. Data collected from monitoring changes in atmospheric composition, temperature, and pressure can provide models to predict grand scale changes in climate, immediate changes in weather, and local changes in degraded quality due to pollution (including natural sources such as pollen as well as manmade contaminants).
- 20.2 As with the atmosphere, chemical analysis of the oceans and freshwater lakes and rivers reveal chemical composition changes over time related to oxygen content, and pollution. Monitoring water quality for waste (phosphates), industrial pollution (metals), heat pollution (nuclear plant waste), and pesticides is important in maintaining drinking water and agricultural water supplies.
- 20.3 Energy demands increase with population, so finding alternate sources of energy for burning fossil fuels is a key driver in chemical research.
- 20.4 The chemistry of fossil fuel consumption includes studies of coal, methane (natural gas), and petroleum. New chemical processes have enabled more complete extraction of fuels from ores, but also created controversy, particularly in the practices of fracking and tar sand extraction, which may have eventual detrimental effects on the environment.
- 20.5 Chemical studies therefore are shifting to look for alternate sources of energy which are safe for the environment ("green") and which are sustainable -- that is, they do not use up all the available source material but use sources at a rate which allows natural process to renew the resource. More efficient fuel cells which can be recharged, hydrogen battery cells, and biofuels are all options.
- 20.6 We assess the impact of fossil-fuel based energy production on the environment in key areas like air pollition and the greenhouse effect. There is nothing new in climate change, even in historical periods: the climate of Europe changed noticeably for the colder beginning in the 13th century. Our current warrming trend, if sustained, may simply indicate that we are coming out of this period due to changes in the amount of solar energy we receive, or it may be complicated by manmade pollution. Ocean acidification, however, supports the theory that at least some changes are occuring in the CO2 leves in the atmosphere. Increasing plant coverage to provide CO2 "recycling" is key to addressing CO2 increases.
- 20.7 Chemical processes can address some of the environmental issues we face. Oil spills from ocean tankers and excess oil waste from industrial countries can be treated with substances that form emulsions with the oil, absorb the oil, or cause it to form a gel, which allow filters to pick up the more solid forms efficiently. Paints treated with chemicals can reduce human exposure to bacteria, especially in urban conditions where people constantly exchange germs (bacteria and viruses).
If you find these study methods useful, visit the Chapter 20 resources at Cengage "Brain" companion site for our text. Click on the chapter dropdown and select Chapter 20 to use the flashcards and glossary.
Use the MindTap reader version of the textbook to view videos and test your understanding with interactive checkpoints. Check OWLv2 for your homework problems.
Videos for Chapter 20: Principles of Chemical Reactivity: Entropy and Free Energy
There are no Thinkwell Videos on this chapter. However, you may find the discussion of "Green Chemistry" at the American Chemical Society useful.
Homework problems: See your Moodle assignment!
AP LAB #17 GUIDED INQUIRY — — Determine water impurities using gravimetric analysis — Phase I
Become familiar with the method of gravimetric analysis. Identify at least five water sources. Possibilities include:
- the tap water in your house;
- distilled or purified water from which the metals have been removed;
- water which has been standing in soil in your yard (you may need to generate this by creating a puddle and letting it sit for at least 2 hours to dissolve components in the soil; then filter it);
- local natural saltwater and freshwater sources if available;
- artifical salt water from a local aquarium or pet supply store.
- AP2009 16 Analytical Gravimetric Determination
- APGIE Investigation 3: What Makes Hard Water Hard?
- IGHCE Lab 20.3 Quantitative Analysis of SeaWater
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