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0 (1); -3 (1) Nor 3-

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0 (1); -3 (1) Nor 3-

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  • pg 1
									2854                                            Mark Scheme                                  June 2005


                               |        -   alternative              answersfor the same markingpoint
                                                        and acceptable
                               '        =   separates  markingpoints
Abbreviations,                  NOT     =   answerswhich are not worthy of credit
                                ()      =   wordswhichare not essentialtogain credit
annotationsand
                                        =   (underlining) wordswhich must be used to gain credit
                                                          key
conventions used in the                 =
                               ecf          error carriedfonvard
Mark Scheme                    AW       =   alternativewording
                               ora      =   or reverseargument

Mark Scheme                           Unit Code                    Session          Year        Version
Page 1 of 5                             2854                        June            2005          Final


1ai         0 (1);-3 (1) Nor 3-                                                                         2

laii        gain of electrons/oxidation                  goes down (1)
                                       state (of nitrogen)                                              1
            Mark separatelv from 1 a i IGNORE"qainshvdroqen".

laiii                                                                                                   2
                       a a
                         -+
                       [r|r   ' ] .
                      + a

                      H
            [ ' . *                               (1);
                               detailinsidebrackets
            allow four pairshoweverdisplayed.
            plus chargeshown somewhere Mark separately
                                          (1)          and creditif NH4shown
            Bracketsnot essential

1 b i       A 1 0 6 - 1 1 0 ( 1 ) ; B 1 1 8- 1 2 2 ( 1 )                                                2

l bii       CO(NH2)2 HzO --. COz + 2NH3/
                     +                                                                                  2
            CO(NH2)2 HzO --- H2NCOOH+ NHs
                     +
                     side (1); lefthandside (1)
            right-hand

1 c i       rate constant                                                                               1

l cii       Increases                                                                                   1

1 d        acidic(1); nitrogenon rightof PeriodicTable (AW)linp-block/non-metal/                        2
           GroupV(1) Secondmarkdepends first.on

1 e i      phenol                                                                                       1

leii          Oa                                                                                        2
                   _-O- Na*




                   Na* shownat leastonce (1) NOT with covalent
                                                             bond

                      'somerscoresmax. (1
2854                                      Mark Scheme                                   June2005



2a       M, methanol (1); M'.ethanediol (1) (1) if A'.valuescorrect not
                       32                    62                      but                      3
         added, axm   (1)
         masses256(9),a96(g)(subsumes        previousmarks)(canbe rounded I or 2
                                                                         to
         sfl/ ratiostatedof 1:2 or close(1) (Accept1:2)

2b                                                                                            4
                        zor.
                 .\H           H.o+
               ot'
                \u
                               ?
          u/                    zot6-                            'bent'(1);
                        H    H At leastthreewatermoleculesshown
          At leasttwo hydrogenbonds betweenH and O in two differentmolecules
          (1);
          Correct and 6- acrossone hydrogen
                  6+                          bond(1);
          at leasttwo O-H-O straight(1);



                                                                                               A
2ci
                 20
         H-c..
                    H

2 cii             redox
         oxidation/                                                                            1

2 ciii   NaBHa                          Il)
             allowsodiumtetrahydridoborate(l                                                   4
                                                                                                I




2d

          g-O
                 >-<"
          Completely
                         o-H One COOHgroupas partof a molecule
                    correct(1);
                                                             (1);
                                                                                              2



                                   attachments
          Allow OH but not ambiguous




2ei                 -                     "Ca multiplied CzO+"(1);
                                                        by                                    2
               Ko       [Ca'.] [CrOo2-]
                                          completely correct(1)
                                          if [CaC2O4]shownas divisor,can only score
               one.
               K. = [Ca2*llCr1roo2-lscores(1)

2eii     [Ca'*]= [CzO+2-I       statedor implied            =
                                                 (1); [Ca2-] l4o (1); = 4.8 x 10* (1)          3
          Fivefrom:
2f       A g a s ,l i q u i ds o l i d ;
                             ,                                                                5
          B instantaneous         dipole(- induceddipole)/i.d.-i.d.A/an Waalsforces
                                                                    der
         in ethane/     ethanenon-polar;
         C hydrogen                      in
                            bonding ethanediol/ethanedioic    acid;
          D more/stronger         hydrogenbondingin ethanedioic  acid; ignoreattempts
         to quantify
          E diagram this;of
          F relative   strengths imfs; of
         G strongerimf mean highermpUbpt(ora)


                                                                                              22

                                              29
2854                                                                           Mark Scheme                                                                                               June2005


Question   Expected Answers                                                                                                                                                                  Marks
3ai                        (1);        acid/ carboxyl(1) NOT carboxy
           alcohol/hydroxy(l) carboxylic
                                                                                                                                                                                               2
3aii       4 - hydroxy(1);butanoic
                                 acid (1) ignorecommas,     spaces. ALLOW
                                                      dashes,
           other materialbetweenbut-anoic butan-oic
                                          or                                                                                                                                                   2
3bi        ester/lactone
                                                                                                                                                                                                1
3bii       hydrolysis
                                                                                                                                                                                                1
3ci
                                                                                                                                                                                                1




3cii       -OH groups(1); hydrogen bond(1) indication bothgroupshavesame
                                                    that
           shape/fitreceptorsite                                                                                                                                                                3
3ciii      computer(modelling)/          modelling
                                 molecular
                                                                                                                                                                                                1
3civ       (potassium/sodium)                                 (1);
                                              dichromate (sulphuric)                 acid (1);or correct           formulae
           (heat under)refluxif any other marksscored(1)                                                                                                                                        3
3d         Infrared:C=O (1);and no O-H/identify                          C=O as ester(1);therefore                   GBL (1)
           ALLOW GHB/GBHas conclusion first mark scoredand O-H (incorrectly)
                                                                 lF                                                                                                                             o
           identified
           ALLOW nmr marksas followsfor any of these by ecf
                                                GBL                       G H B G H Ba l c o h o l
            idea of different           environments          havingdifferent         shifts(1) allow for other
            substances
                                                                                                                                                                                               2
            idea of heightsor areasin ratio.
                                                 )
            ( a s r i g h to r j u s t i f i e da l l o w1 H ,2 H e t c . 1 : 1 : 1          1:2:2:2.1
            or 1:6:1                            1:2:2
            Correct shifts
            (r 0.2)                                 ,                                                             3 6
                                   1 . 4 , 3 . 72 . 4 9 - 1 5 , . 6 ,1 . 4 , 2 . 4 , 0 . 5 - 4 . 5 0 . 5 - 4 . 5 ,1 ..4 ,
                                                               3
           QWC logical,           threetermsfrom list used correctly                     (2)
                      two termsfrom list used correctly(1)                                                                                                                                             \
           absorption/absorbance,                    wavenumber/cm-1,          bond,proton(NOT in "protonnmr"),
           environment,          shift,peak,(relative)            intensity    (nmr context)
3ei        HA -           H* + A-(or reaction                with waterformingHrO.) products(1);equm(1)
           mark separately                                                                                                                                                                     I


3eii       IHI IA-]/IHAI(2) wrongwayup or no squarebrackets    (1)
                                                          scores
                                                                                                                                                                                               2
3eiii      [H.] = 1.26x 10-3 mol dm-3statedor implied,                    (1);
                                                         unitsnot essential allow
           rounded 1.3
                    to                                                                                                                                                                         4
           lA_l= [H'] statedor implied(1);
                                  = 1.59/1
           K^ = (1.26 x 1O-s12110-1        .58/ 1.6/1 (rounded) 10-5(1); mot dm-3
                                                     .69           x
                            (1)
           markseparately ALLOWecf on K if it is lessthan 0.1
3fi        minimises/  resistschange in (allowmaintains)  pH/pHstaysapproximately
           C n n s . t = n fr r 1 !! _r\ ' rt-r r _vrr lr4 n cr.rrr n .a l l u .m nerr r lrgn t e 1 1 \i ni f U V i iUr { U i nur l U i li V c rl i a d d o d
                                                                             a rrv                            an          af        a \qr                       1 1 \r ni o -a d   fan
                                                                                                                                                                                                (
                                t    r          rr           v      s r                           r I    v                                                      r i    i a U         U

                  pH
           maintain in the body (1); e.g.for enzymereactions/blood
                                                                (1)
                                                                                                                                                                                                4
           QWC: Two sentences;spelling, punctuation
                                                  and grammarcorrect(1 error                                                                                                                       I




           allowed),(1)



                                                                                              30
                           Mark Scheme                               June2005


lHAl= [A-]
Thus = K"(1)
    [H-]
pH= tSi .Se
        t  x10-5 4.8 (1)ignore Ku= 1 x 10-5gives5.0 as PH.ecf from
               =             sf'
K , < 0 . 1i n 3 e i i i


                                 acid/azodyes
fertilizers/ make explosives/nitric
           to

nitrogenALLOW b{ X9fI
             Nr

'uii"",iti6"t Pnzo Q); -
 Pco Pnz3llcua
            eic'epttoroNE of the following,scores(1)
. hydrogennot cubed
.                  shownALLOW squarebracketswith "p"
 . "on""iltt"tions
   wrongway up
 NO CREDITif +

 pCO= K, pCHa  pH2OlpH23 stated implied
                          (1)     or
       qizz-ati'(1i i st mirk separately      someworking answer
                                       provided         if
 ;aO =
 incorrect(1)

 ALLOW ecf from wreng J           in 4c(i) or firstmarkingPoint.

 more(gas)molecules right-hand
                    on          side (1);
 decrealingpressuremovei equilibrium(position) direction more
                                             in         of
            increasepresswelt;SLLOW "movesto right"
 molecules/to                                          lF first marking
 pointscored.
 more hydrogenProduced (1)


                                                       between
  speedup reaction/ flow throughplanvcompromise optimum
                  get                         or


  69+H2o+Co2+H2|eft-handside(1);righthandside(1)equmor

  two from:
  toxic/poisonous/harmful life;
                         to
  causes photochemical  smog
  can be burntas a fuel;
                which are useful; NOT

  positivemust be presentto score,but only scoresif qualified at leastone
                                                             by
  of:

   moreways of arrangi
                                                    -
   products reactants ); (198+ 393)- (186+ 189)= 591 375
           -       (1
         (
   3x 131 1);
         answer
   correct     (+216) othercorrectty
                     or               worked answerwithsign(1)
                                            out




                                  3l
     2854                                      Mark Scheme                             June2005


    5a          C , 1 9( 1 ) ; H , 1 6 ( 1 )
                                                                                                 2
    5b        reflects/does absorb/transmits
                           not                (Nor emits)yellow(1); absorbsall
                                                          -                                      2
              other/complementary  colours/wavelengths )'
                                                    (1
            i "reflects
                      only yellow"scoresboth.

    5ci                 are).not
                               associated one bond/pair atoms(1);spread
                                        with         of
            i !"|":t!?n?                                               over                   2
            i severat atomsNOTwhole  molecule(1)
            I
    5cii    I (all)benzenerings(1); N=N (1); (o atomsof) -oH (1) AW in ail parts.
                                                                                              3
    5ciii       lowerexcitationenergy(Nor "easierto excite"/ first energylevellower (1); E
                = hv.lf                                                                       2
                              decreases
                      .requency        with decreasing disiancebetw6enenergylevels

    5di         cH3cl (1);Alcl3(1);anhydrous/reflux formulae
                                                    (1)         mustbe correct.Names
                permitted.Award last onlv if some other mark scored.                          3

    5 dii       H (on a benzene ring)(1); is repraced/substituted     (1) mark
                                                               byrcr-lg
                separately
                                                                                              2

    Sdiii       electrophilic
                                                                                              1
    5ei         diazonium(salt)
                                                                                              1
    5eii        HO
                                                                                              2




i
                      cHs
            nothingon crucialcarbon(1); rest of structure dependson
                                                         (1)
l                                                                   first
            allowsodiumsalt

    5f      four from
                                                                                             4       (
            hydrogen  bondingin connection with cotton;
            dye cannot break cotton-water bonds/waterbreaks dye-cotton
                                                                       bonds ;
            permanent  dipole-permanentdipolein connectionwiih polyester;
            inslantaneous                                      '--'r
                          dipole-induceddipolein dye;
            Lll ql polyester
                           and dye matchbetter/more betweendye and polyester
                                                     imf
            (Am(1)

                                                                                             24




                                                 a^
                                                 JZ

								
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