Edexcel Jan 2014 (IAL) Paper 3 Q2 (with explained solutions) |

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Edexcel Jan 2014 (IAL) Paper 3 Q2

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2 The skeletal formulae of two compounds with molecular formula C6H12O are shown below. OH cyclohexanol OH hex-5-en-1-ol (a) Each of the compounds reacts when warmed with a mixture of potassium dichromate(VI) and sulfuric acid. (i) What colour change is seen during this reaction? Fromto(ii) One of the compounds forms a carboxylic acid when it is heated under reflux with a mixture of potassium dichromate(VI) and sulfuric acid. Give the structural formula of this carboxylic acid. (1) (1) *P42974RA0416*<br />
(b) Under suitable conditions, each of the compounds reacts slowly with a small piece of sodium to form a sodium salt and one other product. Give two observations you would make when this reaction occurs. (2) Observation 1Observation 2(c) Hex-5-en-1-ol can be distinguished from cyclohexanol by its reaction with aqueous bromine. (i) What colour change would be seen in this reaction when hex-5-en-1-ol is used? Fromto(ii) Complete the skeletal formula below to show the product of this reaction. (1) (1) OH *P42974RA0516* Turn over<br />
(d) Hex-5-en-1-ol reacts with acidified potassium manganate(VII) at room temperature. (i) What colour change would be seen in this reaction? Fromto(ii) Complete the skeletal formula below to show the product of this reaction. (1) (1) OH (e) The infrared spectrum below is for either cyclohexanol or hex-5-en-1-ol. Transmittance / % 90 80 70 60 50 40 30 20 4000 3000 2000 1500 Wavenumber / cm1 *P42974RA0616*<br />
For which of the two compounds is this the infrared spectrum? Use two pieces of data from the table below to justify your answer. Bond Wavenumber / cm1 C H stretch, alkane C H stretch, alkene C C stretch, alkene O H stretch, alcohols 29622853 31003010 16691600 37503200 (2) Spectrum is forJustification:(Total for Question 2 = 10 marks) *P42974RA0716* Turn over<br />
BLANK PAGE *P42974RA0816*<br />

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Question Number 2(a)(i) Acceptable answers Orange to green / blue / brown ALLOW Dark green / green-brown Question Number 2(a)(ii) CH2=CH(CH2)3COOH Acceptable answers Double bond need not be shown ALLOW CO2H for COOH ALLOW ALLOW displayed formula OH Reject Mark Combinations of blue and green Green to orange Reject Mark C6H10O2 Formulae not showing H atoms Acceptable answers Reject Mark Any TWO of Bubbles / effervescence / fizzing Sodium dissolves / disappears White residue / solid / ALLOW White precipitate ALLOW Rise in temperature / gets hotter / heat is given out IGNORE Moves / Floats / Sinks / Catches fire / Hydrogen given off Acceptable answers Brown / red-brown / orange / yellow / combinations of these colours to colourless Just Gas forms Bubbles form if incorrect gas identified. White solid dissolves Crystals form Just exothermic Reject Mark Red to colourless Clear for colourless Paler for colourless White for colourless Question Number 2(b) Question Number 2(c)(i)<br />
Acceptable answers OH Br ALLOW Br OH OH Br ALLOW Br OH IGNORE orientation of Br and OH, eg both Br pointing down IGNORE lengths of bonds Check that there are 6C in formula OH Reject Mark Br at left hand end without a bond to it Question Number 2(c)(ii)<br />
Acceptable answers Reject Mark Purple / pink to colourless ALLOW For purple pink: pinkish-purple, dark purple For colourless: brown Clear for colourless White for colourless Green / orange for colourless Lilac for purple Acceptable answers Reject Mark OH OH OH IGNORE orientation of OH, eg both OH pointing down IGNORE lengths of bonds Check that there are 6C in formula OH at left hand end without a bond to it Bond to H of OH group Reject Mark Acceptable answers hex-5-en-1-ol Alkene/ C=C at 16691600 (cm-1) (alkene) C-H at 3100-3010 (cm-1) Correct identification and one correct piece of evidence (1) Correct identification with two pieces of evidence (2) Correct identification and correct bonds quoted without any data can score 1. Total for Question 2 = 10 marks Question Number 2(d)(i) Question Number 2(d)(ii) Question Number 2(e)<br />

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