ALKALINE BA TTERIES
Alkaline batteries are common in electronic devices used in everyday life; however, the way in which they produce electricity is little understood. They are typically constructed with a high-surface-area zinc anode (the positive end) and a manganese dioxide cathode (the negative end). Inside the battery case is a potassium hydroxide electrolyte that is gelled with a cellulose derivative. This electrolyte allows electrons to flow from the anode to the cathode. When the circuit is completed, this flow of electrons powers the electronic device. Although there are many different types of batteries, the construction is typically the same. What varies from battery to battery is the composition of the anode, cathode, and electrolyte. Alkaline batteries were derived from the older “dry cell”-type batteries and were put into commercial production in the early 1950s. A battery is nothing more than a contained chemical reaction that creates an electron potential gradient. The zinc anode is oxidized to form zinc hydroxide-releasing electrons. The manganese dioxide at the cathode is reduced by electrons from the zinc, which are carried to the cathode through the electrolyte solution. Although this is the most common type of alkaline battery in use, some alkaline batteries use mercury and silver in their construction. These metals, especially mercury, can be highly toxic and can be problematic to dispose of properly. Batteries may rupture when exposed to excess heat that accelerates the chemical reaction. This may release harmful flammable or corrosive materials that can result in serious chemical burns and skin irritation.
CORR ECTIONFLUID
The invention of White Out and other correction fluids was spawned by the need of Edwin Johanknecht for a correction fluid that worked on photostatic paper. In 1971, Johanknecht and his partners incorporated their new business, White-Out Products, Inc., providing correction fluid to users all over the world. Correction fluids usually contain a proprietary mixture of solvents and whiteners that act much like a thin fast- drying paint. Typically, methyl chloroform (1,1,1-trichloroethane) is used as a fast-drying solvent in which pigments such as titanium dioxide and other colorants are suspended. Correction fluid is brushed across the paper to cover mistakes and once dry can be written or typed over. Although the product is marketed for consumer use, there are a number of hazards associated with it. Inhalation of large amounts of solvent vapor may cause unconsciousness and may irritate the mucus membranes of susceptible individuals. It can also have a long-term effect on the central nervous system and cause abnormal heartbeats in humans. The dried correction fluid can be especially hazardous if burned, releasing small amounts of phosgene, hydrogen chloride, and chlorine. The formula will react with strong bases and oxidizing agents as well as reactive metals. For these reasons, it is important that correction fluid be used according to the manufacturer’s instructions.
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