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HYDROCARBONS
HYDROCARBONS ARE COMPOUNDS OF CARBON AND HYDROGEN, SEVERAL IMPORTANT FAMILIES OF HYDROCARBONS, EACH CONTAINING MANY COMPOUNDS, ARE WELL KNOWN. SUCH FAMILIES OF HYDROCARBONS ARE KNOWN. SUCH FAMILIES OF HYDROCARBONS ARE KNOWN AS HOMOLOGOUS SERIES, AND ALL THE MEMBERS HAVE FORMULAS THAT FIT THE GENERAL FORMULA OF THE SERIES. THE PRINCIPAL HOMOLOGOUS SERIES OF HYDROCARBONS ARESUMMARIZED IN TABLE XLVI
ALTHOUGH THE ALKENE AND CYCLOPARAFFIN SERIES HAVE THE SAME FORMULA, THEY BEHAVE CHEMICALLY QUITE DIFFERENTLY. IN THE ALKENE SERIES THERE IS A DOUBLE BOND PRESENT BETWEEN TWO CARBON ATOMS WHICH GREATLY INCREASES THE CHEMICAL REACTIVITY OF THESE HYDROCARBONS. IN THE CYCLOPARAFFIN SERIES, THE CARBON ATOMS ARE JOINED TO EACH OTHER, FORMING A RING. SUCH A STRUCTURE IS RELATIVELYINERT.
BOTH THE PARAFFIN AND THE CYCLOPARAFFIN SERIES ARE SAID TO BE SATURATED BECAUSE THEY CONTAIN ONLY SINGLE BONDS. BECAUSE OF THEIR WIDESPREAD AND IMPORTANT USES, SOME OF THE HYDROCARBONS DESERVE SPECIAL MENTION.
METHANE, CH4. THIS GASEOUS COMPOUND IS THE CHIEF INGREDIENT OF NATURAL GAS. UNDER THE NAME MARSH GAS IT ESCAPES FROM PEAT BOGS AND IS RESPONSIBLE FOR THE EERIE WILL-O' - THE - WISPOBSERVED WHEN IT BECOMES IGNITED OVER THESE SWAMPS. UNDER THE NAME FIRE DAMP IT IS THE GAS THAT ESCAPES FROM COAL, WHICH HAS BEEN RESPONSIBLE FOR MANY DISASTROUS MINE EXPLOSIONS. IT IS HIGHLY COMBUSTIBLE AND IS AN EXELLENT FUEL. LIKE ALL OF THE OTHER BASIC HYDROCARBONS, IT IS AN IMPORTANT RAW MATERIAL FOR THE MANUFACTURE OF SYNTHETIC ORGANIC CHEMICALS.
ETHANE. C2H6. THIS GAS MAKES UP ABOUT 10% OFNATURAL GAS. ITS USES ARE SIMILAR TO THOSE OF METHANE.
PROPANE, C3H8. THIS IS ONE OF THE COMMONLY USED INGREDENTS IN BOTTLED GAS. IT IS ALSO USED AS A HIGH PRESSURE SOLVENT.
BUTANE, C4H10. IN ADDITION TO BEING USEFUL AS A BOTTLED GAS AND AS A SOLVENT, BUTANE IS USED IN THE PRODUCTION OF HIGH TEST GASOLINE. ACTUALLY THERE ARE TWO BUTANES, NORMAL BUTANE, CONTAINING A STRAIGHT CHAIN OF CARBONATOMS, AND ISOBUTANE, WHICH HAS A BRANCHED CARBON CHAIN. IT IS THIS ISOMER THAT IS USED IN MAKING SPECIAL GASOLINE. THE PREFIX "NORMAL" (n-) ALWAYS REFERS TO A STRAIGHT
CHAIN OF CARBON ATOMS. THE PREFIX "ISO-" ALWAYS REFERS TO A BRANCHED CHAIN OF CARBON Atoms. the structures of the ISOMERS of BUTANE ARE AS FOLLOWS:
|-\_-
OCTANE, C8H18. THIS COMPOUND HAS 18 ISOMERS, ONE OF WHICH ,(CH3)3CCH2CH(CH3)2, ISOOCTANE, IS THE REFERENCE COMPOUND FOR RATING THE OCTANE NUMBER OF GASOLINE IS THE PERCENTAGE OF ISOOCTANE THAT MUST BE ADDED TO N-HEPTANE, C7H16 TO CAUSE A STANDARD ENGINE TO OPERATE WITH THE SAME CHARACTERISTICS AS THE GASOLINE BEING TESTED. PURE ISOOCTANE HAS A RATING OF 100. HIGH TEST AUTOMOTIVE GASOLINES NOW HAVE OCTANE NUMBERS BETWEEN 90 AND 98. AVIATON GASOLINES HAVE OCTANE NUMBERSABOVE 100, WHICH SIMPLY MEANS THAT THEY GIVE BETTER PERFORMANCE IN THE STANDARD ENGINE THAT PURE ISOOCTANE.
PETROLEUM REFINING:. IN THE REFINING OF PETROLEUM, MANY USEFUL MIXTURES OF HYDROCARBONS ARE MADE AVAILABLE. THE BASIC PROCESS IN REFINING IS FRACTIONAL DISTILLATION, WHICH SEPARATES THE VARIOUS PRODUCTS FORMED BY THE INITIAL DISTILLATION
OF CRUDE PETROLEUM ARE KNOWN AS STRAIGHT RUNPRODUCTS. TABLE XLVII GIVES THE MAIN PRODUCTS FORMED, TOGETHER WITH OTHER PERTINENT INFORMATION ABOUT THEM.
SINCE GASOLINE IS ONLY A SMALL PORTION OF THE STRAIGHT RUN PRODUCT, AND SINCE THE DEMAND FOR IT IS SO GREAT, OTHER STEPS ARE INTRODUCED INTO THE REFINING PROCESS TO INCREASE THE YIELD OF GASOLINE.
THE TWO BASIC STEPS ARE:1. POLYMERIZATION. IN THIS PROCESS, MOLECULES CONTAINING LESS THAN THEPROPER NUMBER OF ATOMS OF CARBON FOR GASOLINE ARE CAUSED TO BE LINKED TOGETHER TO FORM LARGER MOLECULES WHICH FIT INTO THE GASOLINE RANGE UNDER THE INFLUENCE OF PROPER CATALYSTS.2. CRACKING. IN THIS PROCESS, THE LARGE MOLECULES FROM THE PRODUCTS BEYOND THE GASOLINE RANGE ARE BROKEN APART, EITHER BY HEAT OR BY CATALYTIC ACTION, TO FIT THE GASOLINE RANGE.
REFINED GASOLINE, ESPECIALLY HIGH-TEST...
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