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Edexcel Jun 2010 Paper 4 Q18
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![Question Number 18 (a)(i) Question Number 18 (a)(ii) Question Number 18 (a)(iii) Question Number 18 (a)(iv) Acceptable Answers (Acid) hydrolysis Reject Mark substitution Acceptable Answers Reject Mark 2 K2Cr2O7 / Na2Cr2O7 / Cr2O7 Potassium dichromate((VI)) / sodium dichromate((VI)) / dichromate((VI)) ions ALLOW manganate((VII)) ions, etc Acceptable Answers Lithium tetrahydridoaluminate/ lithium aluminium hydride/ LiAlH4 (in dry ether) Just dichromate chromates Correct formula with wrong name and vice versa Incorrect oxidation number Reject Mark Just [H] Acceptable Answers Reject Mark Methyl butanoate (1) CH3CH2CH2COOH + CH3OHCH3CH2CH2COOCH3 + H2O (1) ALLOWIGNORE state symbols even if wrong Methyl butoate<br />
Question Number 18 (a)(v) Question Number 18 (b)(i) Question Number 18 (b)(ii) Acceptable Answers Reject Mark O Cl CH3 CH2 CH2 C Dont penalise undisplayed methyl groups as here. COCl must be displayed as above. C3H7 for CH3CH2CH2 Acceptable Answers Reject Mark Nitrogen inert / unreactive / less reactive (than oxygen) OR Oxygen might react with chemicals going through column / sample might oxidise Acceptable Answers Reject Mark Solubility (in liquid / stationary phase) OR Interaction with liquid / stationary phase OR Interaction between mobile and stationary phase OR Attraction for liquid / stationary phase OR Strength of (named) intermolecular forces OR Adsorption on liquid / stationary phase OR Absorption on liquid / stationary phase Size of molecule / molar mass Polarity, unless with explanation Boiling point / volatility Viscosity Attraction for carrier gas Just a named intermolecular force Just retention time Density<br />
Question Number 18 (c)(i) Question Number 18 (c)(ii) Acceptable Answers Reject Mark O C O H C CH2 CH3 O C H C CH2 CH3 OR H C CH3 CH2 H O C O C O CH2 C CH3 Ester link including C=O (1) Rest of polymer with oxygens at end correct (1) All H atoms must be shown. PENALISE lack of displayed C=O once only ACCEPT Without brackets around formula but bonds at end should be shown More than two correct units IGNORE n after brackets Acceptable Answers Reject Mark Just breaks polymer down Hydrolysis OR Splits / breaks ester link OR polymer breaks down to monomers OR equation showing hydrolysis<br />](https://learnah.org/wp-content/uploads/2018/08/June_2010_MS_-_Unit_4_Edexcel_Chemistry_A-level_18-0.jpg)
