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Edexcel Jun 2009 Paper 1 Q21
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![SECTION B Answer ALL the questions. Write your answers in the spaces provided. 21 This question is about hydrocarbons. (a) Liquefied petroleum gas (LPG) is a fuel sold as an alternative to petrol. It is a mixture of liquefied C3 and C4 alkanes. (i) Suggest a reason why the alkanes are liquefied. (1)(ii) There are two C4 alkanes. Draw skeletal formulae of each of the C4 alkanes in the spaces provided. Name each alkane. First skeletal formula Second skeletal formula (4) Name:Name:10 (iii) Complete the following sentence. (1) Compounds with the same molecular formula but different structural formula are called*H34471A01028*<br />
(b) Propane, C3H8, reacts with chlorine, Cl2, in a substitution reaction. C3H8 + Cl2C3H7Cl + HCl The mechanism for this reaction is described in three stages. (i) Give the initiation step for this reaction and state the condition necessary for this step to occur. (2) Initiation step Condition(ii) Give the TWO propagation steps for this reaction. (iii) Give a possible termination step for this reaction. (2) (1) *H34471A01128* 11 Turn over<br />
(c) Myrcene, C10H16, is a naturally occurring compound which is used in perfumes. H3C CH CH2 CH CH2 CH3 CH2 CH2 Myrcene (i) Name the functional group in myrcene. (1)(ii) What colour change would you observe when bromine, dissolved in an organic solvent, is added to myrcene? (1) FromTo(iii) Classify the type and mechanism of the reaction that occurs when myrcene reacts with bromine, Br2. (2)12 *H34471A01228*<br />
(iv) In an experiment, 1.36 g of myrcene (molar mass: 136 g mol1) was found to react with 0.72 dm3 of hydrogen, H2, in the presence of a nickel catalyst. Use this information to draw the structural formula of the product of the reaction between myrcene and hydrogen. [Assume the molar volume of H2 under the conditions of the experiment is 24 dm3mol1.] (2) Calculation Hence structural formula of the product *H34471A01328* 13 Turn over<br />
(d) Myrcene is one of a group of compounds related to 2-methylbut-2-ene shown below. CH3 CH3 CH3 2-methylbut-2-ene undergoes addition polymerization in a similar way to ethene. Draw the structural formula of the repeat unit of the polymer formed. (2) (Total for Question 21 = 19 marks) 14 *H34471A01428*<br />
BLANK PAGE *H34471A01528* 15 Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/l_smalljpgJune_2009_QP_-_Unit_1_Edexcel_Chemistry_A-level_21-0.jpg)
![Mark Mark Section B Question Number 21 (a)(i) Question Number 21 (a)(ii) Reject Just cost Correct Answer Easier to transport / easier to store / less space / less volume needed for storage / easier to handle / easier to transfer IGNORE references to safety Accept Denser/cheaper to transport OWTTE Reject Correct Answer skeletal formula (1) Name: butane (1) Stand alone skeletal formula (1) Name: methylpropane OR 2-methylpropane (1) IGNORE incorrect punctuation [e.g. extra/missing hyphens, etc.] Stand alone IGNORE displayed formulae if also given with skeletal formulae if 2 correct displayed formulae are given max 1 out of 2 for the structures<br />
Question Number 21 (a)(iii) Question Number 21 (b)(i) Question Number 21 (b)(ii) Question Number 21 (b)(iii) Question Number 21 (c)(i) Correct Answer (Structural) isomers Correct Answer Cl2Cl + Cl / Cl22Cl (1) (U.V.) light / sunlight (1) Must show the dotsIGNORE any subsequent propagation steps in (b)(i) Correct Answer C3H8 + ClC3H7 + HCl (1) C3H7 + Cl2C3H7Cl + Cl (1) Must show the dotsCorrect Answer C3H7 + ClC3H7Cl OR Cl + ClCl2 OR C3H7 + C3H7C6H14 Must show dots in termination step Correct Answer Alkene / triene Accept Diene Carbon-carbon double bond Reject Reject heat alone Reject Reject Reject Mark Mark Mark Mark Mark<br />
Correct Answer Reject From: Red / brown / orange / yellow or combinations of these colours To: colourless both colours needed clear instead of colourless Mark Mark Mark Reject Reject Question Number 21 (c)(ii) Question Number 21 (c)(iii) Question Number 21 (c)(iv) Correct Answer Electrophilic (1) addition (1) Correct Answer Calculation: 0.01 mol myrcene reacts with 0.03 mol H2 OR 1 mol myrcene reacts with 3 mol H2 (1) Structural formula: (CH3)2CH(CH2)3CH(CH3)CH2CH3 (1) OR H3C C CH3 CH3 H Accept Fully displayed formula/skeletal formula Mark calculation and structural formula independently.<br />
Question Number 21 (d) Correct Answer Reject Mark Reject Mark Question Number 22 (a)(i) repeat unit (1) continuation bonds shown (but these bonds do not have to cut through the brackets) (1) n not essential IGNORE the position of n relative to the repeat unit (e.g. can be written as a superscript) Correct Answer Energy change Letter Lattice energy for sodium chloride Enthalpy change of atomization of sodium Enthalpy change of atomization of chlorine First ionization energy of sodium First electron affinity of chlorine Enthalpy change of formation of sodium chloride 6 correct letters (3) 5 or 4 correct letters (2) 3 or 2 correct letters (1) 1 or 0 correct letters (0) H/kJ mol-1 -775 +109 +121 +494 -411<br />](https://learnah.org/wp-content/uploads/2018/08/June_2009_MS_-_Unit_1_Edexcel_Chemistry_A-level_21-0.jpg)
