must show C=C Penalise sticks once per pair 1 H 10 Penalise sticks once per pair 1 or CH 3 C 2 Penalise sticks once per pair 1

Transcription

1 M. (a) A allow CH COCH B must show C=C Penalise sticks once per pair (b) C CH CH CH CH CH D NOT cyclopentane which is only C 5 H 0 Penalise sticks once per pair (c) E CH CH COOCH Allow C H 5 CO CH F CH COOCH CH Allow CH CO CH CH or CH CO C H 5 Penalise sticks once per pair Page of 9

2 (d) G allow C H 7 allow C H 7 allow C H 5 not C 5 H nor C 4 H 9 Penalise sticks once per pair H allow C H 5 (e) I allow C H 5 J NOT C H 7 Penalise sticks once per pair [0] M. (a) (i) or RCOCH ; (or description in words) (ignore trailing bonds) (ii) H C O or ROCH ; (allow if both (i) and (ii) give CH - or H C only) Page of 9

3 (iii) CH CH or two adjacent methylene groups; (iv) OR CH COCH CH OCH ; (b) (i) OH in acids or (carboxylic) acid present (ii) (c) reagent K Cr O 7 /H + KMnO 4 /H + Y no reaction no reaction Z orange to green or turns green purple to colourless or turns colourless 5 [9] M. Test bromine (water) / iodine Accept Br or bromine in a named solvent. Do not accept Br Use of UV light, CE (lose next mark as well) Observation orange / yellow / (red-)brown to colourless Must have correct reagent to score this mark. For I, allow red-brown / purple to colourless. [] Page of 9

4 or CH COOH or HCOOCH M4. (a) A any C 5 alkene B (b) C D or HOCH CHO (c) E F Page 4 of 9

5 (d) G H (e) I J NOT hex--ene [0] M5. (a) M have the same molecular formula or are C H 6 O or both have the same number/amount of each type of atom or same amount of each element or are isomers Not just the same atoms; M identical / exactly the same / same precise (relative) molecular mass / formula mass / M r Same (relative) molecular mass / formula mass / M r is NOT enough got score M Allow same accurate (relative) molecular mass / formula mass / M r Ignore reference to number of decimal places Page 5 of 9

6 (b) M prop--en--ol Must refer to this compound clearly by name or structure (not to alcohol alone); ignore minor slips in name/structure M O(-)H (alcohol) and (cm ), or C=C and (cm ) Marked independently from M Could score from bond labelled on correct signal on spectrum Allow any value within these ranges If additional incorrect signals given penalise M Ignore signals below 500 cm and C-H signals (c) (i) Determine the level by looking at the chemical content. (NB - If there is clear breakage of covalent bonds then max level (max marks). (ii) The mark within that level is then determined by looking at how coherent and logical the answer is and by use of terminology; start at the higher mark and penalise poor terminology/explanation; examples of terminology that would reduce the mark to the lower one: reference to van der Waals bonds or dipole-dipole bonds in relevant compounds that are being credited uncertainty about whether hydrogen bonds are the O-H bonds within or are forces/bonds between molecules (if the alcohol is being credited) use of vdw or dip-dip unless these terms van der Waals for dipoledipole have been used elsewhere in answer (note that IMF and H-bond would not be penalised) (iii) If the answer does not achieve level, then mark maximum could be scored for any correct point from the list of indicative content Level Relative order of boiling points of all three compounds Strongest intermolecular force of all three compounds identified Answer explains this coherently and logically and uses correct terminology for all three compounds 5-6 marks Level Relative boiling points of two compounds correctly compared Strongest intermolecular force for these two compounds correctly identified Answer explains this coherently and logically and uses correct terminology for these two compounds -4 marks Level One compound with the highest or lowest boiling point is correctly identified Strongest intermolecular force for that one compound identified Answer explains this coherently and logically and uses correct terminology for this one compound Allow mark for individual correct point from indicative content on the right if no other mark scored - marks Page 6 of 9

7 Level 0 None of the indicative chemistry content given. 0 marks Indicative chemistry content: Correct order (highest to lowest) = prop--en--ol > propanal > butane Prop--en--ol has hydrogen bonds Propanal has (permanent) dipole-dipole forces Butane has van der Waals forces Strength of intermolecular forces: hydrogen bonds > dipole-dipole > van der Waals (Note - actual values for reference are prop--en--ol 97 C, propanal 46 C and butane C) [0] M6. (a) (i) M double-headed curly arrow from the lone pair of the bromide ion to the C atom of the CH Penalise additional arrows. M double-headed arrow from the bond to the O atom As follows (ii) M nucleophilic substitution M both words needed (allow phonetic spelling). M -bromo(--)methylpropane M Require correct spelling in the name but ignore any hyphens or commas. (b) M hydrolysis For M give credit for hydration on this occasion only. M C N with absorption range 0 60 (cm ) Credit mark from M and M for identifying C N and either O H (acids) or C=O or C O without reference to wavenumbers or with incorrect wavenumbers. M O H(acids) with absorption range (cm ) OR C=O with absorption range (cm ) OR C O with absorption range (cm ) Apply the list principle to M Page 7 of 9

8 (c) (i) M Yield / product OR ester increases / goes up / gets more M (By Le Chatelier s principle) the position of equilibrium is driven / shifts / moves to the right / L to R / in the forward direction / to the product(s) M requires a correct statement in M (The position of equilibrium moves) to oppose the increased concentration of ethanol to oppose the increased moles of ethanol to lower the concentration of ethanol to oppose the change and decrease the ethanol If no reference to M, marks M and M can still score BUT if M is incorrect CE=0 If there is reference to pressure award M ONLY. (ii) M Catalysts provide an alternative route / pathway / mechanism OR surface adsorption / surface reaction occurs For M, not simply provides a surface as the only statement. M may be scored by reference to a specific example. M that has a lower / reduced activation energy OR lowers / reduces the activation energy Penalise M for reference to an increase in the energy of the molecules. For M, the student may use a definition of activation energy without referring to the term. Reference to an increase in successful collisions in unit time alone is not sufficient for M since it does not explain why this has occurred. [] Page 8 of 9

9 M7. (a) Reagent Acidified K Cr O 7 Acidified KMnO 4 I / NaOH Named RCOOH with HCl or H SO 4 Named RCOCl Allow names including potassium permanganate Wrong or no reagent CE = 0 P (ketone) no reaction no reaction Yellow ppt no reaction no reaction Penalise incorrect formulae or incomplete reagent, such as K Cr O 7 or acidified dichromate, but mark on. (b) S ( alcohol) (orange to) green (purple to) colourless no reaction fruity or sweet smell Misty fumes Allow no change or nvc but penalise nothing or no observation If reagents added sequentially or different reagents used for P and S then CE = 0 Tollens silver mirror / solid Fehling s / Benedicts red ppt (c) G P 5 OR five If not P then no marks for clip Page 9 of 9

10 (d) C 4 H Si Must be molecular formula Wrong substance CE = 0 for clip Any two from One or single peak OR all (four) carbon atoms are equivalent or one environment upfield from others or far away from others or far to right non toxic OR inert low boiling point or volatile or easy removed from sample Ignore and don t credit single peak linked to equivalent H or has a peak at δ = 0 but use list principle for wrong statements (e) Figure is R If not R cannot score M M (ppm) or value in range is (two peaks for) C = C / alkene M Figure is T If not T cannot score M4 or M5 M (ppm) or value in range is C O or alcohol or ether M4 two peaks (so not S which would have only one) M5 (f) Page 0 of 9

11 Answers include Not allow S because V must be an isomer of S [7] M8. (a) (i) M (yellow precipitate is) silver iodide OR AgI (which may be awarded from the equation) M Ag + + I AgI (Also scores M unless contradicted) M sodium chloride OR NaCl For M Accept multiples Ignore state symbols Allow crossed out nitrate ions, but penalise if not crossed out (ii) The silver nitrate is acidified to react with / remove ions that would interfere with the test prevent the formation of other silver precipitates / insoluble silver compounds that would interfere with the test remove (other) ions that react with the silver nitrate react with / remove carbonate / hydroxide / sulfite (ions) Ignore reference to false positive Page of 9

12 (iii) M and M in either order M Fluoride (ion) OR F M Silver fluoride / AgF is soluble / dissolves (in water) no precipitate would form / no visible /observable change Do not penalise the spelling fluoride, Penalise fluride once only Mark M and M independently (b) M Ba + + SO 4 - BaSO 4 (or the ions together) M white precipitate / white solid / white suspension M Barium meal or ( internal ) X-ray or to block X-rays M4 BaSO 4 / barium sulfate is insoluble (and therefore not toxic) For M, ignore state symbols Allow crossed out sodium ions, but penalise if not crossed out For M, ignore milky If BaSO OR BaS used in M and M4, penalise once only For M Ignore radio-tracing For M4 NOT barium ions NOT barium NOT barium meal NOT It unless clearly BaSO 4 4 (c) M (.00000) + 4(.00794) = M Ethene and CO or they have an imprecise M r of 8.0 / 8 OR Ethene and CO or they have the same M r to one d.p. OR These may be shown by two clear, simple sums identifying both compounds Page of 9

13 M C H 4 + O CO + H O (H C=CH ) M4 Displayed formula M5 Type of polymer = Addition (polymer) M must show working using 5 d.p.for hydrogen Penalise similar or close to, if this refers to the imprecise value in M, since this does not mean the same For M, accept CH =CH OR CH CH For M4, all bonds must be drawn out including those on either side of the unit. Penalise sticks Ignore brackets around correct repeating unit but penalise n Penalise additional 5 [5] M9.D [] M0. -chloropropane no visible change Accept small amount of precipitate or precipitate forms slowly. ethanoyl chloride white precipitate Accept large amount of precipitate or precipitate forms immediately. [] Page of 9

14 M. (a) M acidified potassium dichromate or K Cr O 7 / H SO 4 OR K Cr O 7 / H + OR acidified K Cr O 7 M (orange to) green solution OR goes green M (solution) remains orange or no reaction or no (observed) change If no reagent or incorrect reagent in M, CE = 0 and no marks for M, M or M If incomplete / inaccurate attempt at reagent e.g. dichromate or dichromate(iv) or incorrect formula or no acid, penalise M only and mark on For M ignore dichromate described as yellow or red For M ignore nothing (happens) or no observation Alternative using KMnO 4 / H SO 4 M acidified potassium manganate(vii) / potassium permanganate or KMnO 4 / H SO 4 OR KMnO 4 / H + OR acidified KMnO 4 M colourless solution OR goes colourless M (solution) remains purple or no reaction or no (observed) change For M If incomplete / inaccurate attempt at reagent e.g. manganate or manganate(iv) or incorrect formula or no acid, penalise M only and mark on Credit alkaline KMnO 4 for possible full marks but M gives brown precipitate or solution goes green Page 4 of 9

15 (b) M (Shake with) Br OR bromine (water) OR bromine (in CCl 4 / organic solvent) M (stays) orange / red / yellow / brown / the same OR no reaction OR no (observed) change M decolourised / goes colourless / loses its colour / orange to colourless OR as alternatives If no reagent or incorrect reagent in M, CE = 0 and no marks for M, M or M If incomplete / inaccurate attempt at reagent (e.g. Br), penalise M only and mark on No credit for combustion observations; CE = 0 For M in every case Ignore nothing (happens) Ignore no observation Ignore clear Use KMnO 4 / H SO 4 M acidified potassium manganate(vii) / potassium permanganate OR KMnO 4 / H SO 4 OR KMnO 4 / H + OR acidified KMnO 4 M (stays) purple or no reaction or no (observed) change M decolourised / goes colourless / loses its colour Use iodine M iodine or I / KI or iodine solution M no change M decolourised / goes colourless / loses its colour Use concentrated sulfuric acid M concentrated H SO 4 M no change M brown For M, it must be a whole reagent and / or correct formula For M penalise incorrect attempt at correct formula, but mark M and M With potassium manganate(vii) If incomplete / inaccurate attempt at reagent e.g. manganate or manganate(iv) or incorrect formula or no acid, penalise M only and mark on Credit alkaline / neutral KMnO 4 for possible full marks but M gives brown precipitate or solution goes green Apply similar guidance for errors in the formula of iodine or concentrated sulfuric acid reagent as those used for other Page 5 of 9

16 reagents. (c) M Any soluble chloride including hydrochloric acid (ignore concentration) M white precipitate or white solid / white suspension M remains colourless or no reaction or no (observed) change or no precipitate or clear solution or it remains clear OR as an alternative M Any soluble iodide including HI M yellow precipitate or yellow solid / yellow suspension M remains colourless or no reaction or no (observed) change or no precipitate or clear solution or it remains clear OR as an alternative M Any soluble bromide including HBr M cream precipitate or cream solid / cream suspension M remains colourless or no reaction or no (observed) change or no precipitate or clear solution or it remains clear OR as an alternative M NaOH or KOH or any soluble carbonate M brown precipitate or brown solid / brown suspension with NaOH / KOH (white precipitate / solid / suspension with carbonate) M remains colourless or no reaction or no (observed) change or no precipitate or clear solution or it remains clear If no reagent or incorrect reagent or insoluble chloride in M, CE = 0 and no marks for M, M or M Allow chlorine water If incomplete reagent (e.g. chloride ions) or inaccurate attempt at formula of chosen chloride, or chlorine, penalise M only and mark on For M require the word white and some reference to a solid. Ignore cloudy solution OR suspension (similarly for the alternatives) For M Ignore nothing (happens) Ignore no observation Ignore clear on its own Ignore dissolves Page 6 of 9

17 (d) M Any soluble sulfate including (dilute or aqueous) sulfuric acid M remains colourless or no reaction or no (observed) change or no precipitate or clear solution or it remains clear M white precipitate or white solid / white suspension OR as an alternative M NaOH or KOH If no reagent or incorrect reagent or insoluble sulfate in M, CE = 0 and no marks for M, M or M Accept MgSO 4 and CaSO 4 but not barium, lead or silver sulfates If concentrated sulfuric acid or incomplete reagent (e.g. sulfate ions) or inaccurate attempt at formula of chosen sulfate, penalise M only and mark on For M (or M in the alternative) require the word white and some reference to a solid. Ignore cloudy solution OR suspension For M (or M in the alternative) Ignore nothing (happens) Ignore no observation Ignore clear on its own Ignore dissolves M white precipitate or white solid / white suspension M remains colourless or no reaction or no (observed) change or no precipitate or clear solution or it remains clear If incomplete reagent (e.g. hydroxide ions) or inaccurate attempt at formula of chosen hydroxide, penalise M only and mark on If M uses NH (dilute or concentrated) penalise M only and mark on [] M. (a) (i) Green Ignore shades of green. (ii) Excess acidified potassium dichromate(vi) Reflux (for some time) In the diagram credit should be given for a vertical condenser Lose M and M4 for a distillation apparatus. an apparatus which would clearly work Do not allow this mark for a flask drawn on its own. Penalise diagrams where the apparatus is sealed. Page 7 of 9

18 (iii) Distillation Immediately (the reagents are mixed) (b) Keep away from naked flames Allow heat with water-bath or heating mantle. If a list is given ignore eye protection, otherwise lose this mark. (c) (i) Tollens or Fehling s reagents Incorrect reagent(s) loses both marks. Accept mis-spellings if meaning is clear. Silver mirror / red ppt. formed Accept blue to red but not red alone. (ii) Sodium carbonate (solution) / Group II metal Allow indicator solutions with appropriate colours. Accept any named carbonate or hydrogen carbonate. Effervescence / evolves a gas Accept fizzes. (d) Propanoic acid If this mark is lost allow one mark if there is reference to stronger intermolecular forces in the named compound. Lose M and M. Contains hydrogen bonding Some comparison with other compounds explaining that the intermolecular forces are stronger in propanoic acid [5] Page 8 of 9

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