This is the way to test for a double C=C bond in a molecule. Īlkenes will react with bromine water and turn it from orange/brown to colourless. For example, ethene molecules can react together to form poly(ethene), a polymer. In order for it to be useful to us, crude oil is broken down in oil refineries into its component parts, known as fractions, and these can then be used for many different purposes. Crude oil AND in the cracking process, to make ethene. Alkenes can take part in reactions that alkanes cannot. Cracking is a thermal decomposition process by which. alkenes are unsaturated, they contain at least one C=C double bondĪs a result, alkenes are more reactive than alkanes.alkanes are saturated, their carbon atoms are only joined by C-C single bonds.AlkenesĪlkanes and alkenes both form homologous series of hydrocarbons, but: Since cracking converts larger hydrocarbons into smaller hydrocarbons, the supply of fuels is improved. Smaller hydrocarbons are more useful as fuels than larger hydrocarbons. Very often, fractional distillation of crude oil produces more of the larger hydrocarbons than can be sold, and less of the smaller hydrocarbons than customers want. The demand is how much of a fraction customers want to buy. The supply is how much of a fraction an oil refinery produces. It produces alkenes, which are useful as feedstock for the petrochemical industry.It helps to match the supply of fractions with the demand for them.Butane and ethene are produced Reasons for crackingĬracking is important for two main reasons: Give one problem caused.ħ © UCLES 2012 0620/22/O/N/12 [Turn over For Examiner’s Use 4 The process of distillation is used in an oil reﬁ nery to separate petroleum into different.3. You may use a pencil.Ħ Do not write outside the box (06) G/T94145/Jun13/8402/1 3 Poly(ethene) is a polymer with many uses. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. You may need to use a pencil for any diagrams, graphs or rough working. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name in the spaces at the top of this page. UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certicate of Secondary Education *2998687209* CHEMISTRY Paper 2 Candidates answer on the Question Paper. Organic Chemistry Homework 2 - Alkanes and Alkenes Name: ………………………………………. UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certi cate of Secondary EducationĪlkane and Alkene 1.

The minimum energy to produce a 360-degree bond rotation is called the rotational. Rotating a molecular substructure about a twistable bond usually requires energy.

Cracking of dodecane to make ethene