The best way to remember the information in this chapter is to get a pen and paper and write down your answers. The straight chain alkanes share the same general formula. And be careful with your phrasing cracking produces alkenes and shorter chain alkanes. The larger alkanes are heated to around 650c and their vapours are passed over a hot catalyst. Cracking of alkanes craking refers to the process where cc bonds in long chain alkanes molecules are broken, producing smaller molecules of alkanes and alkenes. A level chemistry aqa specification alkanes modification of alkanes by cracking quick jump menu unit 1 notes unit 2 notes unit 3 experimental unit 4 notes unit 5 notes unit 6 experimental home. Cracking is a very important process used in the petrochemical industry to break down the large hydrocarbons intro smaller hydrocarbons, which burns more easily as fuel. Nov 14, 2017 in this video, we look at how cracking is used to convert longchain hydrocarbons into shorterchain hydrocarbons. This blog only covers the organic chemistry topics which are included on the igcse chemistry syllabus. Covers thermal and catalytic cracking, ppt file, application questions, answers and an assessed homework activity with mark scheme. The breaking of longer chain alkanes in order to produce a smaller alkane and an alkene. Vapours will then pass over a hot catalyst of silica. The chemistry of cracking results in the formation of smaller, more useful alkanes such as petrol, and even more useful alkenes such as ethene. As chemistry aqa cracking alkanes teaching resources.
Alkanes consist of strong covalent bonds therefore they are, on the whole, quite unreactive. Cracking oil and cracking gcse chemistry single science. There is a greater demand for smaller hydrocarbons than larger ones. Cracking edexcel igcse chemistry notes save my exams. See all chemistry resources see all crude oil, cracking and hydrocarbons. Vapours will then pass over a hot catalyst of silica or alumina. State why there is a need for cracking to be performed on. Pupils can share their ideas in pairs, then as a class, before being introduced to the process of cracking.
The fractional distillation of crude oil produces alkanes. This is called catalytic cracking and is an example of a thermal decomposition reaction. Gcse chemistry revision questions fossil fuels crude. Crude oil hydrocarbons and alkanes aqa test questions aqa. Learn about crude oil, hydrocarbons and alkanes with bitesize gcse chemistry aqa. We also look at alkenes and how we test for alkenes using bromine water.
Their most important reaction is that of combustion. Learn gcse chemistry alkanes with free interactive flashcards. Combustion substitution with halogens catalytic cracking. The alkanes from pentane through to c 16 are liquids with the remainder larger molecules being solids. Outline of practical work is included but follow centre basedcleaps safety guidelines. By the end of this lesson ks5 students should be able to. Give two examples of properties of hydrocarbons that are dependent upon the size of the hydrocarbon molecule.
Apparatus delivery tube and bung bunsen burner boiling tube containing mineral wool porous pot liquid paraffin clamp and stand. High octane starter to inject pace which is easily adapted for other lessons. At fuse school, teachers and animators come together to make fun. For example, as the chain length increases, their boiling point increases. Targeted towards aqa c1 topic 5 but suitable for edexcel and other exam boards too. Cracking is the name given to breaking up large hydrocarbon molecules into. Heat longchain hydrocarbon to vaporise it, pass the vapour over a hot catalyst. Year 12 lesson graded outstanding to teach cracking. Petrol and other fuels are produced from it using fractional distillation.
All liquid alkanes are less dense than water and therefore float on it. Alkenes along with alkanes can be produced from cracking. Crude oil hydrocarbons and alkanes aqa test questions. Covalent bonds are formed when atoms share pair of electrons. From the physical properties of the alkanes, it can be established that. They cover formation of crude oil, hydrocarbons, alkanes, fractional distillation, alkenes and polymerisation. Catalytic cracking takes place at a slight pressure, high temperature and in the presence of a zeolite catalyst and is used mainly to produce motor fuels and aromatic hydrocarbons mechanism not required. Choose from 500 different sets of gcse chemistry alkanes flashcards on quizlet. Most of the hydrocarbons in crude oil are hydrocarbons called alkanes. Hydrocarbons are chain molecules of varying lengths made from hydrogen and carbon atoms only, joined together by covalent bonds.
A brief description of the difference between thermal and catalytic cracking of alkanes. Hydrocarbons from oil a2levellevelrevision, chemistry. This video prepares students for gcse higher tier science. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Oct 25, 2017 lesson planpowerpoint to teach cracking of alkanes. This is achieved by using high pressures and temperatures without a catalyst, or lower temperatures and pressures in the presence of a catalyst. Cracking oil fractions reaction conditions products equations. The main chemical reactions that alkanes undergo are. Before joining or doing any activity please read the guidelines of the. Cracking fuels edexcel gcse chemistry single science. Alkanes alkanes are saturated hydrocarbons contain single. Chemistry revision notes on the topic cracking hydrocarbons. Dec 31, 2015 summary video on cracking for gcse chemistry. Gcse chemistry revision covering cracking and its products, hydrocarbons, catalyst, thermal decomposition, alkanes, single covalent bonds, alkenes, double covalent bonds, and cracking paraffin.
Fractions containing large hydrocarbon molecules are heated at 600 700c to vaporise them. Designed by expert teachers for the edexcel gcse 91 chemistry syllabus. Cracking hydrocarbons in liquid paraffin with a catalyst. This makes them relatively unreactive, apart from their reaction with oxygen in the. This means that their carbon atoms are joined to each other by single bonds.
They do not react with acids, alkalis, and oxidising agents. Cracking is used to convert long alkanes into shorter, more useful hydrocarbons. If you are an igcse chemistry student desperately looking for the perfect organic chemistry notes, then this is the one. Please comment if you have any questions, and subscribe if you. Gcse chemistry what is the chemistry of the cracking of. A hydrocarbons are broken down 1 mark to produce smaller more useful molecules 1 mark. Learn the basics about the cracking of hydrocarbons and why it is done. To describe what cracking is and its economic benefits. As well as using a normal type of molecular formula to describe an organic molecule, they can be represented by drawing out their structure i. Written by teachers for the edexcel igcse chemistry course. Alkanes have all cc single bonds and alkenes have cc double bond.
You need to understand certain chemical reactions used in a variety of industrial processes for gcse chemistry. A structured lesson including starter activity, afl work tasks on cracking of alkanes. In this video, we look at how cracking is used to convert longchain hydrocarbons into shorterchain hydrocarbons. Organic chemistry introduction 1 structural formulae. The covalent bond is broken so each carbon has this mechanism. Stick with shorter as opposed to short because if you crack a larger alkane you could end up with an alkane as a product that you wouldnt normally describe as short. Cracking helps match supply of fractions with demand. Graded with a video link and mark schemes for everything. Cracking is the name given to breaking up large hydrocarbon molecules into smaller and more useful bits. After the fractional distillation of crude oil there are too many large hydrocarbons and not enough small hydrocarbons to meet the publics demand. The american chemist, william burton, is usually credited with being the inventor of the thermal cracking process. Aqa gcse 91 chemistry 8462 past exam papers and marking schemes, the past papers are free to download for you to use as practice for your exams.
Cracking cracking is the breaking down of an unsaturated hydrocarbon into smaller hydrocarbons. Gcse chemistry unit 1 cracking alkanes to make alkenes. Learn about and revise fuels with this bbc bitesize gcse chemistry edexcel study guide. Written by teachers for the cie igcse chemistry 91 course. These resources are specifically designed for senfoundation students studying gcse chemistry ocraqa. Gcse chemistry what is the cracking of hydrocarbons. Nov 04, 2009 how many grams of liquid can be produced from decomposition of 758. The general formula means that the number of hydrogen atoms in an alkane is double the number of carbon atoms, plus two. Give an example of a method by which cracking can be carried out.
Some of the large hydrocarbons the heavier fractions are broken down into more useful smaller hydrocarbons lighter fractions by a process known as cracking. The purpose of cracking is to produce high demand hydrocarbons. You need to know about alkanes, alkenes, crude oil and the process of cracking. Gcse chemistry senfoundation crude oil, alkanes, frac.
Learn about fuels from crude oil with bitesize gcse combined science ocr gateway. To compare and evaluate the conditions for and the products of thermal and catalytic cracking. Best igcse organic chemistry notes complete breakdown. Model the industrial process of cracking larger hydrocarbons to produce smaller alkanes that can be converted into petrol. Cracking is a thermal decomposition process by which large alkane hydrocarbon. Two methods of cracking how to write a balanced equation for cracking what an alkene is, and how they differ from an alkane. Alkenes are reactive molecules that are used to make plastics and other chemicals. Aqa chapter 7 hydrocarbons in this lesson students will learn. Gcse chemistry revision organic chemistry crude oil. Cracking and alkenes crude oil, hydrocarbons and alkanes. An alkene is produced because the original alkane does not have enough hydrogen atoms to produce two more alkanes. C 16 h 34 is an alkane which can be used as the starting chemical in cracking. One of these is thermal cracking which is used on crude oil.
Cracking an alkane produces a smaller alkane plus an alkene. Cracking and alkenes crude oil, hydrocarbons and alkanes aqa. First, crack the vapour of liquid paraffin by passing it over a heated catalyst to produce and collect a mixture of gaseous shortchain hydrocarbons. Organic chemistry now forms a substantial part of the gcse specifications. This makes them relatively unreactive, apart from their reaction with oxygen in the air, which is called combustion, or burning. Cracking allows large hydrocarbon molecules to be broken down into smaller, more useful hydrocarbon molecules. Cracking hydrocarbon chains will be expected for all three exam boards which are. If you add up the number of hydrogen atoms in the above reaction, you will see that there are 22 on each side. Gcse chemistry unit 1 cracking alkanes to make alkenes cracking alkanes to make alkenes. In addition to this you will need to know about functional groups such as alcohols, carboxylic acids and esters and how to draw their structures. Thermo cracking is used to break down high molecular mass alkanes into low molecular mass alkanes as well as alkenes using heat and a catalyst. New91 aqa gcse chemistry c9 crude oil and fules kerboodle. Crude oil hydrocarbon alkane cracking alkene polymer objectives. The viscosity of liquid alkanes increases as the number of carbon atoms increase.
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