Edexcel Jan 2013 Paper 2 Q23 (with explained solutions) |

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Edexcel Jan 2013 Paper 2 Q23

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23 The skeletal formula of cyclohexanol is shown below. OH (a) (i) The actual bond angles differ from the angles in the two dimensional diagram shown. What is the angle of the CCC bond labelled a? (1) Angle*(ii) What is the angle of the COH bond? Justify your answer, explaining why the size of the angle is different from the angle in (i). (3) AngleExplanation(b) (i) Suggest what you would expect to see when cyclohexanol reacts with sodium. (2)14 *P41213A01424*<br />
(ii) Phosphorus(V) chloride (phosphorus pentachloride) is used to test for the presence of an OH group. Write the equation for the reaction of cyclohexanol with phosphorus(V) chloride. (iii) Give the chemical test you could use to identify the gas produced, and the observation you would make. (2) (1)(iv) Cyclohexanol reacts with hot acidified potassium dichromate(VI) solution. Give the skeletal formula of the organic product of this reaction. (v) What colour change would you observe as this reaction takes place? (1) (1) Fromto(c) The mass spectrum of cyclohexanol has a prominent peak at mass / charge ratio 82. Suggest the molecular formula of the fragment which causes this peak. (1)(Total for Question 23 = 12 marks) TOTAL FOR SECTION B = 41 MARKS *P41213A01524* 15 Turn over<br />

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Mark Mark Reject Reject Lone pairs repel H atoms Mark Reject Just Hydrogen forms/gas forms Fumes Acceptable Answers uestion Number 23(a)(i) 109 () / 109.5 () / 109 28/ Question Number 23(a)(ii) 104106 () (1) Acceptable Answers O atom has two lone pairs (and 2 bonding pairs) (1) This mark can be given independently of the first and third mark Lone pairs repel each other more than bonding pairs / angle is reduced to minimise repulsion (by lone pairs) / to maximise separation (of lone pairs) (1) Ignore bonds repel each other Angle in (ii) must be smaller than in (i) for third mark to be given Question Number 23(b)(i) Any two from Acceptable Answers Fizzing / effervescence / bubbles (of gas) (1) Sodium dissolves / disappears / reduces in size (1) White solid /precipitate forms (1) Ignore identification of products even if incorrect. Ignore sodium melting / moving around / sinking / floating Ignore colourless solution forms Ignore temperature changes / sodium going on fire<br />
Mark Reject C5H11COH CH2CH2CH2CH2CH2CHOH Unless a bond is shown connecting C1 and C6 Mark Reject Just steamy / misty fumes Just testing with an indicator Bleaches litmus Reject Reject Mark Mark (Colour change from) Orange to green / blue / brown blue- green green-blue yellow to green Acceptable Answers Question Number 23(b)(ii) C6H11OH + PCl5HCl + C6H11Cl + POCl3 (1) (1) (1) for HCl (1) for rest of the equation correct Cyclohexanol can be skeletal, C6H11OH/ C6H12O Accept PCl3O instead of POCl3 Accept skeletal formula for C6H11Cl Cl Ignore state symbols Question Number 23(b)(iii) White smoke / solid with ammonia Acceptable Answers Allow white fumes / dense white fumes / steamy white fumes OR White precipitate with silver nitrate Ignore reference to ammonia solution unless HCl is specifically bubbled into solution Ignore using an indicator to show gas is acidic with one of the above tests Ignore description of appearance of HCl before testing Question Number 23(b)(iv) Acceptable Answers =O Acceptable Answers Question Number 23(b)(v)<br />
Question Number 23(c) Acceptable Answers (+) C6H10 Mark Reject C6H10 (CH2)5C C5H10C C6H11 (CH)5OH C2(CH2)3O Total for Q23 = 12 marks<br />

Question 21 22 23 24

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