3. Agriculture

The carbon in decaying organic matter uses oxygen to form carbon dioxide. This increased concentration of carbon dioxide causes the ground water flowing through to become acidic. Acidic soils are sour soils.

Limestone (calcium carbonate, CaCO3) is applied to acid soils to produce a pH that is slightly basic. Such a soil is called a sweet soil.

Some species of millipedes store the compound mandelonitrile. When attacked by a predator, the millipede combines an enzyme with the mandelonitrile and discharges a toxic repellant, hydrogen cyanide, HCN.

The whip scorpion, which is only a few centimeters long, can accurately direct a spray many times that distance at a predator. The spray contain a mixture of three organic carboxylic acids:

Although acetic acid is the actual irritant, its effectiveness is enhanced by the presence of caprylic acid. Caprylic acid permits penetration of the waxy coating found on many recipients.

Formicinae ants defend themselves by discharging a spray of formic acid.

Try to plan field trips to a water or sewage treatment plant, a food processing plant, or dairy in your area. Invite knowledgeable people in your area associated with one of these to your classroom to discuss the chemistry involved in their particular plant.

Lactic acid, sauerkraut, hot BBQ suace--all find their way to our tables. The relationship between acids and foods is a rich one to explore. (Idea contributed by Angie Matamoros)

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