Paraffin wax is a familiar substance because it is used to make candles. It is a soft, white solid at room temperature that melts and burns easily. Its chemical composition is a mix of hydrocarbon molecules known as alkanes. Paraffin wax melts at temperatures between 125 and 175 degrees Fahrenheit, depending on its exact mixture. The wax has a number of uses and was instrumental in the discovery of a subatomic particle, the neutron.
The general formula for paraffin wax involves n carbon atoms and 2n plus 2 hydrogen atoms, where n is at least 16. For example, one of the hydrocarbons in the wax might have the formula C31H64. In the manufacture of paraffin wax from petroleum, different amounts of refining can change the mix of hydrocarbons and thereby modify some of the wax's properties, such as its melting point. Manufacturers make the wax by removing the oil from a waxy byproduct of petroleum distillation. In addition to its historical significance in helping to identify the neutron, paraffin wax is used in many applications, including investment casting, coatings, sealants, lubricants, candles and crayons.
Discovery of the Neutron
The high hydrogen content of paraffin wax prompted James Chadwick to use the substance in 1932 to discover the existence of an electrically neutral subatomic particle that he named the neutron. Chadwick used a radioactive element, polonium, as a source of alpha radiation, which is a stream of high-energy electrons. He directed the alpha radiation at a beryllium target that then gave off its own radiation. Chadwick directed this electrically neutral secondary radiation into a sample of paraffin wax within a chamber attached to a Geiger counter. The secondary radiation caused ionized protons -- hydrogen atoms stripped of their electrons -- to register on the counter. The number of displaced paraffin wax protons indicated that the neutral secondary radiation contained particles of approximately the same size as protons -- neutrons.
(Ref 4) Metal parts, such as turbine blades, are often manufactured using the investment casting, or “lost wax” process, which relies on the molding of wax patterns. Paraffin wax is one of several types of waxes suitable for making patterns, and the wax may contain additives that increase its usefulness. The procedure is to create a master pattern from plastic, wood, wax, clay or metal and then create a rubber or metal mold, the master die, from the pattern. Molten wax is then poured into the master die, either in many small layers or all at once. After the wax patterns cool and harden, ceramic materials are applied to produce the investment, which is a mold into which molten metals are cast.
Paraffin wax is non-toxic, indigestible and used to coat foods such as candies and cheeses. It can be used to seal containers and as an additive to chewing gum. Its ability to resist caking and moisture makes it a useful addition to fertilizers. Surfers often wax their boards with paraffin wax mixture known as surfwax that adds grip. As a glide wax, it helps skis and snowboards slip through snow and ice. Paraffin wax is found in a wide range of products, including solid inks, rubber compounds, peanut butter balls, waxed paper, paintballs, textiles, petroleum jelly and lip balm.
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