Camphor

Camphor, volatile, white, crystalline compound,with a characteristic aromatic odor. Ordinary camphor is obtained from the camphor tree, Cinnamomum camphora, which grows in Asia and Brazil. The camphor is distilled by steaming chips of the root, stem, or bark. The leaves of certain plants, such as tansy and feverfew, contain a second form of camphor, which is not used commercially. A racemic form is present in the oil of an Asian chrysanthemum and is also produced synthetically for most commercial uses. Camphor is used in the manufacture of celluloid and explosives and medicinally in liniments and other preparations for its mild antiseptic and anesthetic qualities. It is poisonous if ingested in large amounts.

Camphor is insoluble in water, soluble in organic solvents, and melts at 176° C (349° F) and boils at 209° C (405° F).

Ozone

Ozone (Greek ozein, “to smell”), pale blue, highly poisonous gas with a strong odor. Ozone is considered a pollutant at ground level, but the ozone layer of the upper atmosphere protects life on Earth from the Sun’s harmful ultraviolet radiation.

Ozone is one of three forms, called allotropes, of the element oxygen. Ozone is triatomic, meaning that it has three atoms in each molecule (formula O3). Ordinary, or diatomic, oxygen (O2) is more stable than ozone and accounts for the bulk of oxygen in the atmosphere. Electrical sparks and ultraviolet light can cause ordinary oxygen to form ozone. The presence of ozone sometimes causes a detectable odor near electrical outlets.

PROPERTIES

At normal temperatures and pressures ozone is a gas with a specific gravity of 2.144 (about 1.5 times the density of ordinary oxygen gas). Ozone accounts for only a tiny fraction of the atmosphere and is normally invisible, but high concentrations of ozone gas are pale blue. The gas condenses to a liquid at -111.9°C (-169.52°F) and freezes at -192.5°C (-314.5°F). Liquid ozone is deep blue, and is diamagnetic (repelled by magnetic fields). Solid ozone is dark purple. Ozone is much more active chemically than ordinary oxygen. It is used in purifying water, sterilizing air, and bleaching certain foods.

Learn more:

ENVIRONMENTAL EFFECTS

Chlorofluorocarbons (CFCs)

Chlorofluorocarbons (CFCs), family of synthetic chemicals that are compounds of the elements chlorine, fluorine, and carbon. CFCs are stable, nonflammable, noncorrosive, relatively nontoxic chemicals and are easy and inexpensive to produce. During the 1970s, scientists linked CFCs to the destruction of Earth’s ozone layer. The manufacture of CFCs has since been banned in most countries.

USES

Scientists developed the first CFCs during the late 1920s. The compounds subsequently became used in a wide range of industrial products in the United States, Europe, and Japan. Manufacturers used CFCs as refrigerants in refrigerators, freezers, air conditioners, and heat pumps, and as propellants in aerosols and medical inhalers. CFCs also served as insulating foams in packaging materials, furniture, bedding, and car seats. Cleaning agents for electronic circuit boards, metal parts, and dry cleaning processes also used CFCs.

Learn more:

• Harmful Effects of CFCs
• Regulation
• Extended Impact