OCR A Jan 2013 Paper 2 Q1

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Answer all the questions. 1 Crude oil contains many hydrocarbons. The table shows information about some of these hydrocarbons. Hydrocarbon Molecular formula Boiling point / C Hexane 3-Methylpentane 2,2-Dimethylbutane C6H14 C6H14 C6H14 69 63 50 (a) What is the empirical formula of hexane?[1] (b) Explain why hexane is both saturated and a hydrocarbon. saturatedhydrocarbon[2] (c) Draw the skeletal formula for 2,2-dimethylbutane. [1] (d) Describe and explain the trend shown by the boiling points of the hydrocarbons in the table.[3]OCR 2013<br />
 (e) Decane, C10H22, can be cracked to form hexane and one other product. Write an equation for this reaction.[1] (f) In the presence of ultraviolet radiation, butane, C4H10, reacts with chlorine to form a large number of organic products. Several of these products are structural isomers of C4H8Cl2. (i) Write an equation, using molecular formulae, for the formation of C4H8Cl2 from butane.[1] (ii) Complete the table below about two of the structural isomers of C4H8Cl2. Isomer 1 Isomer 2 Name 1,4-Dichlorobutane Displayed formulaCl Cl [2] (g) The reaction between butane and chlorine is an example of radical substitution. Initially, chlorobutane, C4H9Cl, is formed, which then reacts with more chlorine to form C4H8Cl2. (i) The first step of the reaction of C4H9Cl with chlorine is the homolytic fission of a chlorine molecule. What is meant by the term homolytic fission?[2] (ii) Complete the missing species in the propagation steps below. Cl + C4H9Cl++C4H8Cl2 +OCR 2013 [2] Turn over<br />
 (h) Butane, C4H10, undergoes incomplete combustion when there is a shortage of oxygen. Write an equation for the incomplete combustion of butane.[1] [Total: 16]OCR 2013<br />

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