林 Petroleum Refining Cracking >converts high molecular weight hydrocarbons to more useful,low molecular weight ones Reforming >increases branching of hydrocarbon chains >branched hydrocarbons have better burning characteristics for automobile enginesPetroleum Refining ™Cracking ¾converts high molecular weight hydrocarbons to more useful, low molecular weight ones ™Reforming ¾increases branching of hydrocarbon chains ¾branched hydrocarbons have better burning characteristics for automobile engines