These notes on cracking alkanes to make alkenes for plastics and other products from cracking like petrol and diesel fuels are designed to meet the highest standards of knowledge and understanding required for students/pupils doing GCSE chemistry, IGCSE chemistry, O Level chemistry and KS4 science courses. Either way, it means the vast majority of crude oil can be turned into useful products. There are two good economic reasons for cracking oil fractions – (i) there isn't enough of fuels like petrol or diesel in the original crude oil and (ii) alkenes are NOT found in oil, so must be manufactured from oil. petrol or diesel) and alkenes which are used to make polymers–plastics and other important compounds. The products are smaller alkanes used for fuels (e.g. – Cracking is a thermal decomposition process by which large alkane hydrocarbon molecules are broken down by passing them over a heated catalyst at high pressure. Cracking – a problem of supply and demand, other products Oil, useful products, environmental problems, introduction to organic chemistryĦ. Although not included your answer should include both chemical equations and a diagramĭoc Brown's GCSE/IGCSE/O Level KS4 science–CHEMISTRY Revision Notes Reorganisation of these leads to the various products of the reaction.2. Ions like this are called carbonium ions (or carbocations). That leaves the carbon atom with a positive charge. The zeolite catalyst has sites which can remove a hydrogen from an alkane together with the two electrons which bound it to the carbon. It also produces high proportions of branched alkanes and aromatic hydrocarbons like benzene. The zeolites used in catalytic cracking are chosen to give high percentages of hydrocarbons with between 5 and 10 carbon atoms - particularly useful for petrol (gasoline). The alkane is brought into contact with the catalyst at a temperature of about 500 ☌ and moderately low pressures. You may have come across a zeolite if you know about ion exchange resins used in water softeners. They are, of course, associated with positive ions such as sodium ions. These are complex aluminosilicates, and are large lattices of aluminium, silicon and oxygen atoms carrying a negative charge. Modern cracking uses zeolites as the catalyst. The octane is one of the molecules found in petrol (gasoline). The ethene and propene are important materials for making plastics or producing other organic chemicals. This is only one way in which this particular molecule might break up. Or, showing more clearly what happens to the various atoms and bonds:
0 kommentar(er)
