Question Answer Mark Guidance 1 (a)

Transcription

1 Question Answer Mark Guidance 1 (a) 1 ALLW correct structural R displayed R skeletal 3 3 formula R mixture of the above 3 D NT ALLW molecular formula Br Br ALLW dichloro or diiodo compound instead of the dibromo compound as the only alternatives. (b) Reagent A: correct halogen e.g. Br 2 / bromine 1 ALLW l 2 if dichloro compound drawn ALLW I 2 if diiodo compound drawn IGNRE state symbols Answer must match box from (a) to score (c) (i) Steam AND acid catalyst 1 ALLW + / named acid / 2 S 4 / 3 P 4 ALLW 2 (g) ALLW water only if a temperature of 100 or above is quoted. IGNRE any temperature given with steam IGNRE pressure (ii) (compounds or molecules) having the same molecular formula but different structural formulae 1 ALLW different structure R different displayed formula R different skeletal formula for structure (iii) Same formula is not sufficient Different arrangement of atoms is not sufficient 2 ALLW correct structural R displayed R skeletal formula R mixture of the above ALLW any vertical bond to D NT ALLW (iv) Does not contain group(s) R does not contain hydroxyl group(s) R is not an alcohol 2 ALLW RA throughout D NT ALLW (ions) / hydroxide (ions) Does not form hydrogen bonds with water Does not form hydrogen bonds is not sufficient

2 Question Answer Mark Guidance (d) Reagents: Acid/ + 2- and (potassium or sodium) dichromate/r ANNTATE ANSWER WIT TIKS AND RSSES seen once ET bservations: range to Green R range to Blue ALLW 2 S 4 and K 2 r 2 7 Distillation / Distil produces aldehyde/ 3 2 : [] ALLW correct displayed formula R correct structural formula R skeletal formula R a mixture of the above D NT ALLW molecular formulae ALLW 3 7 for propan-1-ol in equations D NT ALLW 3 2 for aldehyde Reflux (of propan-1-ol) produces carboxylic acid/ [] Total 14 IGNRE further oxidation of aldehyde ALLW for carboxylic acid

3 Question Answer Marks Guidance 2 (a) (i) E and 1 ALLW pentan-2-ol and 2-methylbutan-2-ol (ii) 1 ALLW 2-methylbutan-2-ol (iii) F 1 ALLW propan-1-ol (b) (i) ALLW any order of atoms D NT ALLW 5 9 (ii) 2-methylpentan-3-ol 1 ALLW 2-methylpentane-3-ol ALLW absence of hyphens or use of commas ALLW space between methyl and pentan D NT ALLW 2-methylpent-3-ol R 2-methypentan-3-ol R 2-metpentan-3-ol, 4-methylpentan-3-ol etc (c) (series of compound) with same functional group and each successive member differing by 2 2 IGNRE with same or similar chemical properties R same or similar chemical reactions IGNRE references to physical properties or named physical properties vary with an observable trend. IGNRE have similar or the same physical properties IGNRE has same general formula ALLW each subsequent member varying by 2 D NT ALLW have the same empirical formula R have the same molecular formula

4 Question Answer Marks Guidance 2 (d) 4 ALLW correct structural R displayed R skeletal formula R mixture of the above (as long as unambiguous) heat with acidified K 2 r 2 7 (aq) heat with 3 and an acid catalyst IGNRE inorganic products if written in, eg 2 for the elimination reactions IGNRE names of compounds heat with an acid catalyst + ALLW in either order Total 11

5 Question Answer Marks Guidance 3 (a) (i) ALLW molecular formulae R correct structural R displayed R skeletal formula R mixture of the above (as long as unambiguous) ALLW correct multiples, including fractions, of this equation IGNRE state symbols D NT ALLW [] (ii) ALLW molecular formulae R correct structural R displayed R skeletal formula R mixture of the above (as long as unambiguous) ALLW correct multiples of this equation IGNRE state symbols D NT ALLW [] (b) (i) 1 nly one carbon atom needs to have the correct partial charge D NT ALLW partial charges on hydrogen atoms + - (ii) Movement of an electron pair 1 ALLW movement of a lone pair R movement of a bond ALLW movement of two electrons (iii) eterolytic 2 MARK INDEPENDENTLY Both electrons (in the bond) go to the same atom R (bond breaks) to make a cation and (a lone pair on the oxygen atom) R bond pair becomes a lone pair on oxygen ALLW one atom gets none of the bonded electrons D NT ALLW both electrons go to a molecule D NT ALLW makes a positive and a negative ion because in this example this is not true (iv) It donates a pair of electrons 1 ALLW donates a lone pair D NT ALLW it donates electrons (v) idea that + ion is used in step 1 AND made in step 4 1 ALLW + ion is used at the start AND made at the end IGNRE overall + is not used up in the mechanism

6 Question Answer Marks Guidance (b) (vi) 1 ALLW correct structural R displayed R skeletal formula R mixture of the above (as long as unambiguous) eg (c) (d) Ethane-1,2-diol has more groups (than ethanol) Stronger hydrogen bonding (between ethane-1,2-diol molecules) ne ester linkage drawn despite the rest of the structure orrect structure for example R ALLW vertical bond to any part of the or 3 group D NT ALLW formula with horizontal R D NT ALLW formula with horizontal 3 R 3 2 ALLW has more hydroxyl groups R has more hydroxy groups R has more alcohol groups Ethane-1,2-diol has two groups is NT sufficient but ALLW ethane-1,2-diol has two groups and ethanol has one D NT ALLW it has hydroxide (ions) ALLW more hydrogen bonds (between ethane-1,2-diol molecules) IGNRE hydrogen bonds with water 2 ALLW correct structural R displayed R skeletal formula R mixture of the above (as long as unambiguous) ALLW ester shown as all the atoms R as R 2 R 2 IGNRE molecular formula

7 Question er Marks Guidance (e) Any two from: 2 Mark incorrect answers first If one incorrect answer maximum of 1 mark If two incorrect answers award 0 marks ALLW instead of ALLW vertical bond to any part of the D NT ALLW formula with horizontal R but ALLW EF if both displayed formulae are drawn this way ALLW one mark if two correct structural R skeletal formula R mixture of the above (as long as unambiguous) are drawn Total 15

8 Question Answer Mark Guidance 4 (a) (i) n 2n ALLW n 2n + 2 (ii) ALLW (b) group of atoms R part of a molecule that give a compound its (characteristic set of) reactions 2 ALLW part of an alcohol IGNRE part of a compound ALLW that determines its chemical properties R that gives the compound its reaction ALLW that determines its homologous series (c) (i) 3 ANNTATE ANSWER WIT TIKS AND RSSES (ii) Alkanes have van der Waals intermolecular forces Alcohols have hydrogen bonds (and van der Waals forces) ydrogen bonds are stronger (than van der Waals forces) R RA Methylpropan-1-ol has weaker van der Waals forces (than butan-1-ol) R RA Methylpropan-1-ol has less surface contact (than butan-1-ol) R RA R Methylpropan-1-ol has more branching (than butan-1-ol) R RA ALLW reference to specific compounds e.g. comparing methane and methanol vdw force is not sufficient here Third marking point is dependent on the correct intermolecular forces being described BUT ALLW hydrogen bonds are stronger than intermolecular forces in alkanes 2 ALLW methylpropan-1-ol has fewer van der Waals forces (than butan-1-ol) IGNRE reference to more surface area / molecules are closer ALLW methylpropan-1-ol is branched and butan-1-ol is not IGNRE methylpropan-1-ol is branched with no comparison

9 Question Answer Mark Guidance (d) (i) 3 + 1½ ALLW for incomplete combustion ALLW 3 + ½ ALLW ½ ALLW correct multiples of these equations IGNRE state symbols (ii) (iii) insufficient supply of oxygen R limited amount of air R poorly ventilated Feedstock (in manufacture of organic compounds) R manufacture of biodiesel R manufacture of esters. 1 1 ALLW manufacture of a named organic compound that can be made from methanol ALLW antifreeze, screenwash (e) 2 ne mark is for the correct structure of the product ne mark is for the equation BUT [] ALLW D NT ALLW 4 8 2, 3 7, 4 7 for the structure mark but ALLW for the equation mark Give credit for the correct structure in the equation e.g [] scores two marks but [] scores one mark [] scores one mark ALLW one mark for: []

10 Question Answer Mark Guidance (f) (i) methylpropan-2-ol R 2-methylpropan-2-ol 2 D NT ALLW methylprop-2-ol ALLW ( 3 ) 3 ALLW vertical bond to any part of the group D NT ALLW horizontal in the formula ALLW (ii) 1 ALLW ALLW Total 18 ALLW vertical bond to any part of the group D NT ALLW horizontal in the formula IGNRE an incorrect name