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Glossary: Chemistry of everyday life
- A very hard, brittle, heat-resistant substance that is used to grind the edges or rough surfaces of an object. boron carbide, diamond, and corundum are abrasives.
- A substance added to food or beverages to lower pH and to impart a tart, acid taste. Phosphoric acid is an acidulant added to cola drinks.
- activated charcoal. activated carbon; active carbon.
- A porous form of carbon that acts as a powerful adsorbent, used to decolorize liquids, recover solvents, and remove toxins from water and air.
- A chemical compound that reacts with chlorine-based bleaches to stop the bleaching. Thiosulfate compounds are antichlors.
- Antioxidants are compounds that slow oxidation processes that degrade foods, fuels, rubber, plastic, and other materials. Antioxidants like butylated hydroxyanisole (BHA) are added to food to prevent fats from becoming rancid and to minimize decomposition of vitamins and essential fatty acids; they work by scavenging destructive free radicals from the food.
- antiozonant. antiozidant.
- Substances that reverse or prevent severe oxidation by ozone. Antiozonants are added to rubber to prevent them from becoming brittle as atmospheric ozone reacts with them over time. Aromatic amines are often used as antiozonants.
- A substance that can lessen or prevent fever.
- aqua regia.
- A mixture of nitric and hydrochloric acids, usually 1:3 or 1:4 parts HNO3 to HCl, used to dissolve gold.
- A dilute solution of sodium hypochlorite or calcium hypochlorite which kills bacteria and destroys colored organic materials by oxidizing them.
- caffeine. (C8H10N4O2) methyltheobromine; guaranine; 1,3,7-trimethylxanthine; 1,3,7-trimethyl-2,6-dioxopurine.
- A substance found in tea, coffee, and cola that acts as a stimulant. It is extremely soluble in supercritical fluid carbon dioxide and somewhat soluble in water; aqueous solutions of caffeine quickly break down.
- carbonate hardness. carbonate water hardness. Compare with water hardness.
- Water hardness due to the presence of calcium and magnesium carbonates and bicarbonates. The "noncarbonate hardness" is due mostly to calcium and magnesium sulfates, chlorides, and nitrates.
- dry cell. Leclanché cell.
- A electrolytic cell that uses a moist paste rather than a liquid as an electrolyte. Flashlight batteries are dry cells with a zinc cup for an anode, a carbon rod for a cathode, and a paste made of powdered carbon, NH4Cl, ZnCl2, and MnO2 for an electrolyte.
- EDTA. ethylenediaminetetracetic acid; versine.
- A polydentate ligand that tightly complexes certain metal ions. EDTA is used as a blood preservative by complexing free calcium ion (which promotes blood clotting). EDTA's ability to bind to lead ions makes it useful as an antidote for lead poisoning.
- A substance added to a formulation that gives it softening ability. For example, oils that can soften skin are added as emollients in some skin creams.
- glutamate receptors.
- Glutamate receptors are protein molecules that helps gate the flow of ions across a nerve cell's membrane. They play a role in the formation of new connections between nerve cells (and so, in learning and memory). The receptors are normally activated by aspartate and glutamate. In amnesic shellfish poisoning, domoic acid acts as an excitotoxin that very strongly activates some of these receptors, preventing their proper functioning.
- Ionic salts of glutamic acid used as flavor enhancers in many foods. Glutamate is usually manufactured by acid hydrolysis of vegetable proteins. Besides being a basic building block of proteins, glutamate functions as a neurotransmitter that helps neurons grow new connections; as such, glutamate plays an important role in learning and memory. At high concentrations, glutamate can function as an excitotoxin.
- glyceride. monoglyceride; diglyceride; triglyceride.
- Glycerides are fats and oils that are esters of glycerol with one or more fatty acids. Monoglycerides, diglycerides, and triglycerides contain one, two, and three fatty acids linked to the glycerol, respectively.
- A substance that absorbs or retains moisture, added to a product to keep it from drying out.
- mixed glyceride. Compare with glyceride.
- A diglyceride or triglyceride that contains more than one type of fatty acid connected to glycerol via an ester linkage. Natural oils and fats usually contain several different mixed glycerides.
- MSG. monosodium glutamate.
- MSG is monosodium glutamate, used as a flavor enhancer in many foods.
- natural gas.
- A mixture of methane and other gases, found trapped over petroleum deposits under the earth.
- permanent hardness. permanent water hardness. Compare with temporary hardness and water hardness.
- Water hardness that remains after boiling the water, mainly due to dissolved calcium sulfate. Chlorides also contribute to permanent hardness.
- 1. A mixture of fuel and oxidizing agent that reacts to produce a high-energy stream of product gases that can produce thrust. For examples, see What makes a good rocket fuel? 2. A compressed gas used to push a material through a nozzle, forming an aerosol or a foam. For example, nitrogen or propane are used as propellants for shaving cream; nitrous oxide is used as a propellant for whipped cream.
- saturated fat. Compare with unsaturated fat.
- A lipid that contains no carbon-carbon double bonds. Animal fats like butter and lard are composed of saturated fat. Saturated fats tend to be waxy or greasy solids.
- A salt of a fatty acid. For example, sodium stearate is a soap made by neutralizing stearic acid. Commercial soaps are mixtures of fatty acid salts.
- temporary hardness. temporary water hardness. Compare with permanent hardness and water hardness.
- The component of total water hardness that can be removed by boiling the water. Ca(HCO3)2 and Mg(HCO3)2_ are responsible for temporary hardness.
- unsaturated fat. Compare with saturated fat.
- A lipid containing one or more carbon-carbon double bonds. Unsaturated fats tend to be oily liquids and are obtained from plants.
- vinyl. polyethylene.
- A polymer made by linking ethylene (CH2=CH2) or substituted ethylene molecules together.
- A substance that is critical for proper functioning of a living organism that the organism is unable to produce in sufficient quantities for itself.
- water gas. blue gas; synthesis gas.
- A fuel gas used in industrial synthesis of organic chemicals, and in welding, glassmaking, and other high-temperature industrial applications. Water gas made by passing steam over a bed of hot coal or coke. It consists mainly of of carbon monoxide (CO) and hydrogen (H2), contaminated with small amounts of CO2, N2, CH4, and O2.
- water hardness. hard water. Compare with water softener.
- Hard water is water contaminated with compounds of calcium and magnesium. Dissolved iron, manganese, and strontium compounds can also contribute to the "total hardness" of the water, which is usually expressed as ppm CaCO3. Water with a hardness over 80 ppm CaCO3 is often treated with water softeners, since hard water produces scale in hot water pipes and boilers and lowers the effectiveness of detergents.
- water softener. soft water; water softening. Compare with water hardness.
- A material that lowers water hardness when dissolved in water. For example, sodium carbonate ("washing soda") softens water by precipitating Ca2+ ions as CaCO3. Zeolites soften water by exchanging Ca2+ ions with Na+ ions.
- water softening. Compare with water softener and water hardness.
- Removal of Ca2+ and Mg2+ from water to prevent undesirable precipitation reactions from occurring in plumbing, pools, washwater, and boilers.
- Addition compounds of the type Na2O·Al2O3·n SiO2·m H2O, with calcium sometimes replacing or present with the sodium. The sodium in the zeolite exchanges with calcium in water, making zeolites useful for water softening. The porous structure of zeolites also makes them effective molecular sieves used as gas adsorbents and drying agents. Artificial zeolites are used as ion exchange resins.
- Process of etching unprotected parts of a zinc plate with strong acids to produce a printing surface.