Chemistry Connections: Acids/Bases, Equilibrium
Description: Discusses the basic chemistry behind the chemicals added to a swimming pool to control bacterial growth and other dissolved pollutants. Covers in detail the role of chlorine, sodium hypochlorite, hypochlorous acid and the hydrogen ion (H+) in the swimming pool equilibrium system. Describes the role of hydrogen ions in determining pH. Includes a student experiment using red cabbage to indicate acidity. This whole issue, April 1983, focuses on acid/base chemistry, with these other topics: Antacids, Shampoo and pH, Acid Rain, and The Acid-Base Concept. No accompanying Teacher’s Guide was produced for this article.
Author: Brian Rohrig
Chemistry Connections: Acids/Bases, Reactions
Description: Discusses at length the process of food processing in the body, including ingestion, digestion, absorption, and elimination. Discusses enzymes (biological catalysts) in saliva, using carbonic anhydrase (not from saliva) as example of the efficacy of catalyzed chemical reactions. Explains the role of hydrochloric acid in stomach digestion—not to break down food, but to provide acidic environment in which digestive enzymes can work (gastric juice). Discusses “heartburn” and its remedies—neutralization of stomach acid using antacids. Also covers roles of pancreas, gall bladder, small intestine and the large intestine and colon. It’s chemistry all the way through the digestive tract!
Author: Brian Rohrig
Chemistry Connections: Acids/Bases, Solutions, Reactions
Description: Introduces sinkholes with several actual news accounts. Describes what sinkhole are, their causes, and how they form. Discusses the geology, chemistry and chemical reactions of acid rain and acidic organic materials reacting with carbonate rock; e.g., limestone, to produce underground caverns that then subside or collapse, producing sinkholes. Includes carbon dioxide, carbonic acid, hydrogen, and hydrogen carbonate ions in the reactions, identifying hydrogen ions as those responsible for acidic conditions. Shows world map that illustrates where carbonate rock is found—areas prone to sinkhole formation. Describes warning signs that precede the formation of a sinkhole and inspection/detection devices that can be used to find one.
Author: Amanda Yarnell
Chemistry Connections: Acids/Bases, Bonding, Solids/Liquids/Gases, Solutions
Description: Discusses the relatively short history of cat litter (<60 years) and the four main types of cat litter—Fuller’s earth, bentonite (Montmorillonite), silica gels and plant-derived materials like Swheat Scoop. Talks about the chemistry of each type, including odor control (by protonation of NH3 to NH4+, absorbents, fragrances and antibacterial agents) and clumping of clays (absorption of water between layers of clay, causing swelling of the clay). Molecular models of Montmorillonite before and after the addition of water are shown.
Author: Christen Brownlee
Chemistry Connections: Acids/Bases, History/Biography, Organic/Biochemistry, Reactions, Solutions
Description: Recounts attempts to find an easy-to-use colorimetric urine test for diabetes. Includes early chemical testing, from the use of copper (II) sulfate-sodium hydroxide-ammonia reagent, to the advance made by Walter Compton who combined the reagents into tablet form (called Clinitest), to the modification made by Helen and Al Free which was a tablet that tested urine for ketone bodies. Describes the paper strip test, also developed by the Frees, which uses glucose enzymes to test for sugar in urine. Eventually the paper strip developed by the Frees contained ten tests in a single strip. The test strips are called Multistix-10SG. Article includes photos of the test strips. An interview with Helen Free follows the article.
Author: Helen Herlocker
Chemistry Connections: Acids/Bases, Equilibrium, Reactions, Sustainability
Description: Explains the greenhouse effect; role of atmospheric chemicals absorbing infrared radiation. Carbon dioxide, water vapor, methane, nitrous oxide, ozone, dichlorodifluoromethane, trichlorofluoromethane listed with their relative effectiveness in absorbing infrared. Diagrams are included.