Jean McDonald, age 12, of Romney, West Virginia, for her question:
What is propane?
Propane is one of those invisible helpers that performs all sorts of everyday chores behind the scenes. It may be a bottled fuel that we use in the lamps and stoves we take on camping trips. It may be processed to make rainproof fabrics and many other plastics. A few people have adjusted their cars to use propane as a fuel. This has a double advantage. It reduces auto emissions that cause air pollution and also conserves our supplies of gasoline.
Gas for the kitchen range is piped to most city dwellings. But the pipes do not reach many people who live way out in the country. They depend on tanks of LPG to heat their ranges. The letters stand for Liquid Petroleum Gases and the main gases in the mixture are propane and butane. They are two of the many hydrocarbon chemicals extracted from petroleum. The LPG mixture may be mostly propane or mostly butane.
The basic propane molecule is a linkage of three atoms of carbon and eight atoms of hydrogen. At ordinary temperatures it forms an invisible, flammable gas. Under pressure, propane gas becomes a liquid fuel that can be stored and transported in heavy containers. Each sturdy container has a valve which can be turned to allow the contents to escape. The freed propane is released from pressure and immediately turns into a jet of fuel gas.
Other supplies of propane are used in the manufacture of a long list of unlikely products. It is one of the invisible ingredients in the antifreeze that protects auto engines during severe weather. There is propane in acetone, which is used to clean paint brushes.
Propane plays many roles in the manufacturing of modern plastics. In most of these fantastic recipes, heat and pressure are used to combine liquid or gaseous propane with various other hydrocarbons. These small molecules may be joined to make larger ones. But in many plastic making recipes, the small hydrocarbon molecules are broken apart, reshaped and strung together in lo chains.
Man made chain molecules are used to make some of our favorite plastics. For example, propane is used in making vinyl, a popular plastic used in floor coverings and chair covering material, in water proof material for making raincoats and dozens of other useful substances. A few years ago, most of our propane supply was used as fuel. Nowadays, more and more is used to manufacture plastics.
Deposits of natural gas are trapped below with some of our deposits of petroleum. Propane can be extracted from both natural gas and petroleum. Often it is extracted with butane and the two are compressed to become the liquid fuel we call LPG. For making plastics, pure propane may be separated from the numerous hydrocarbon chemicals found in precious petroleum.