Learn the basics about the cracking of hydrocarbons and why it is done. This is achieved by using high pressures and temperatures without a catalyst, or lower temperatures and pressures in the presence of a catalyst. At fuse school, teachers and animators come together to make fun. It really isnt that rough of a subject if you put the time in. The higher molecules of alkanes are transformed into lower molecules petrol c 6 to c 11 by cracking. Cracking is the most important process for the commercial production of gasoline and diesel fuel. An alkyl group is a group of carbon and hydrogen atoms attached to an alkane molecule.
However, the higher alkanes have little value and are usually split into lower alkanes by cracking. Cracking edexcel igcse chemistry notes save my exams. Now, sadly, not all alkanes simple organic compounds are straightchain alkanes. The first step in the process is the homolytic cleavage of a hydrocarbon. Branched alkanes differ from continuouschain alkanes in that carbon chains substitute for a. Thermal cracking uses harsh conditions like high temperature and high pressure. In chemistry, it is a process of breaking down large alkane into simpler alkenes and alkanes. Organic chemistryalkanes wikibooks, open books for an. Simply put, hydrocarbon cracking is the process of breaking a longchain of hydrocarbons into. Cracking meaning types of cracking thermal cracking and. In petrochemistry, petroleum geology and organic chemistry, cracking is the process whereby. In absence of air, they undergo pyrolytic cracking. Some of the smaller hydrocarbons formed by cracking are used as fuels eg large chains are often cracked to form octane for petrol, which is in high demand, and the.
Cracking is defined as a process, wherein complex organic molecules namely long chain hydrocarbons or kerogens are broken down into. Cracking, in petroleum refining, the process by which heavy hydrocarbon molecules are broken up into lighter molecules by means of heat and usually pressure. Alkanes are used to obtain finely divided carbon black carbon by thermal cracking, the black carbon is produced by heating methane to c in the absence of air, black carbon is used in the manufacture of car tires, black painting, polishes, and printing ink. Difference between thermal cracking and catalytic cracking. Alkanes are comparatively, inactive compounds because the carbon atoms in alkanes are combined together by the strong sigma bonds, these bonds cant be broken easily except under certain conditions such as burning, substitution and thermal catalytic cracking alkanes are chemically unreactive, they are neither affected by. Alkane definition, any member of the alkane series. This process is used extensively in the petroleum industry for the commercial preparation of low molecular weight hydrocarbon fuels such as gasoline and diesel. Alkane article about alkane by the free dictionary. Cracking is used to convert long alkanes into shorter, more useful hydrocarbons. Alkene definition, any member of the alkene series. Cracking hydrocarbons in liquid paraffin with a catalyst resource. This makes them relatively unreactive, apart from their reaction with oxygen in.
The energy content of the known submarine methane hydrate fields exceeds that of all known natural gas and. Information and translations of cracking in the most comprehensive dictionary definitions resource on the web. This combustion of alkanes is highly exothermic, explaining their use as. Catalytic cracking is the breakdown of large compounds into small hydrocarbons using an acid catalyst. Thermocracking is used to break down high molecular mass alkanes into low molecular mass alkanes as well as alkenes using heat and a catalyst. The process of cracking breaks longer chains alkanes into smaller alkanes and alkenes to increase octane number and to make polymers. Both alkanes and alkenes can be burnt to form heat along with carbon dioxide and water vapor.
Therefore the product obtained from a given alkane depends on. During this process, it involves numerous chemical reactions based on free radicals. Cracking and alkenes crude oil, hydrocarbons and alkanes. Alkyne definition and meaning collins english dictionary. There is a chemical bond between two atoms or groups of atoms when the forces acting between them are strong enough to lead to the formation of an aggregate with sufficient. Cracking is used to convert long alkanes into shorter, more useful. The thermal decomposition of organic compounds is known as pyrolysis but if it applied to the hydrocarbon or alkanes is known as creaking. A brief look at cracking alkanes in the oil industry. The chemical structure of alkanes only consists of single bonds. On heating with regulated supply of air at high pressure and in presence of suitable catalyst. Alkanes with a chain length of approximately 35 or more carbon atoms are found in bitumen, used, for example, in road surfacing. Cracking is the breakdown of a large alkane into smaller, more useful alkenes. Branched alkanes can form linear alkanes but instead of having just a straight chain in their chemical structure, and branched with one or more alkyl groups. Alkanes are chemical compounds that consist of carbon c and hydrogen h atoms, so they are also called hydrocarbons.
In presence of air, alkanes are oxidized to carbon dioxide and water with evolution of large amount of heat. After watching the covalent bonds video you should have sufficient knowledge to understand about how alkanes and alkenes are formed and the differences. Schematic diagram of a fluid catalytic cracking unit. Cracking meaning types of cracking organic chemistry. Similarly cracking of hydrocarbons includes breaking down of a complex long chain of hydrocarbons into smaller ones. Cracking is the name given to breaking up large hydrocarbon molecules into smaller and more useful bits. For example, dodecane a component of kerosene oil gives a mixture of heptane and pentane as pyrolysis products, on heating it to a temperature of 973k under the catalytic action of platinum, palladium or nickel. Cracking and alkenes crude oil, hydrocarbons and alkanes aqa.
Cracking allows large hydrocarbon molecules to be broken down into smaller, more useful hydrocarbon molecules. Petrol and other fuels are produced from it using fractional distillation. Model the industrial process of cracking larger hydrocarbons to produce smaller alkanes that can be converted into petrol. Cracking is a reaction in which larger saturated hydrocarbon molecules are broken down into smaller, more useful hydrocarbon molecules, some of which are unsaturated. Alkane definition of alkane by the free dictionary. This means that their carbon atoms are joined to each other by single bonds. Information and translations of alkanes in the most comprehensive dictionary definitions resource on the web. One important feature of free radical reactions is that isomerization reactions, e. Alkanes are hydrocarbon atoms that consist of single bonds. Since this process is carried out at high temperatures, it is also called pyrolysis, from the greek pyro, fire, and lysys, decomposition. The formation of branchedchain alkanes, or isoalkanes, leads to the production of gasoline with high octane numbers.
The rate of cracking and the end products are strongly dependent on the. Simply put, hydrocarbon cracking is the process of breaking longchain hydrocarbons into short. Alkenes are unsaturated hydrocarbons having the chemical formula c n h 2n. These are organic molecules that consist only of hydrogen and carbon atoms in a treeshaped structure acyclic or not a ring. Alkanes are the simplest organic molecules, consisting solely of singlybonded carbon and hydrogen atoms. Cracking is the process whereby long and medium chain hydrocarbons are heated and break apart giving short chain alkanes, alkenes and hydrogen.
In petrochemistry, petroleum geology and organic chemistry, cracking is the process whereby complex organic molecules such as kerogens or longchain hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carboncarbon bonds in the precursors. The catalytic cracking of high molecular weight hydrocarbons to more. Cracking is the breakdown of a large alkane into smaller, more useful alkanes and alkenes. Although their reactivities are often rather uninteresting, they provide an excellent basis for understanding bonding. The following are some examples for branched alkanes. Alkynes definition of alkynes by medical dictionary. The source of the large hydrocarbon molecules is often the naphtha fraction or. The combustion of alkanes, including incomplete combustion.
Catalytic cracking an overview sciencedirect topics. Cracking, in petroleum refining, the process by which heavy hydrocarbon molecules are broken up into lighter molecules by means of heat and usually pressure and sometimes catalysts. This is the fundamental reason why catalytic cracking has replaced thermal cracking as the central process in a refinery geared to maximize gasoline production. These higher alkanes have little chemical and commercial value and are usually split into lower alkanes by cracking. Alkane definition is any of numerous saturated hydrocarbons. Thermal cracking is the process of breaking down large compounds into small compounds at high temperatures and high pressures. Simply put, hydrocarbon cracking is the process of breaking longchain hydrocarbons into short ones. Learn about crude oil, hydrocarbons and alkanes with bitesize gcse. Thus alkanes are decomposed to lower alkane by heating 500 0 c to 600 0 c. Catalytic cracking produces branched and cyclic alkanes and aromatic hydrocarbons used for making motor fuels branched and cyclic hydrocarbons burn more cleanly and are used to give fuels a higher octane number combustion alkanes readily burn in the presence of oxygen. Cracking of alkanes cracking is a form of thermal decomposition, which breaks long chain hydrocarbons, many of which are not very useful, into shorter molecules by heating them. Alkanes are used as the basis for naming the majority of organic compounds their nomenclature.
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