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					SULIT                                                              4541/2(PP)


4541/2
CHEMISTRY
Kertas 2
Peraturan Pemarkahan
Sept 2010


            PERSIDANGAN KEBANGSAAN PENGETUA-PENGETUA
                SEKOLAH MENENGAH MALAYSIA (PKPSM)
                        CAWANGAN PAHANG



                  PEPERIKSAAN PERCUBAAN TAHUN 2010

                                TINGKATAN 5



                        PERATURAN PEMARKAHAN




   _________________________________________________________________________
                     Kertas ini mengandungi 11 halaman bercetak




4541/2(PP) @ PKPSM Cawangan Pahang 2010                                 SULIT
SULIT                                                                       4541/2(PP)


No.                                 Mark Scheme                     Sub     Total
                                                                    Mark    Mark
 1      (a)(i)    X : electron
                  Y : nucleus                                         1
          (ii)    Electron // X                                       1       2

        (b)(i)    The number of protons in the nucleus of an atom     1

           (ii)   18                                                  1

          (iii)   2.8.7                                               1

          (iv)                                                                6




                                  Number of shells , 3                1
                                  Number of electrons                 1


          (v)     7                                                   1

        (c ) (i) A and B
            (ii) Because A and B has different number of              1
                 neutrons but same number of protons // has
                 different nucleon number but same proton                     2
                 number
                                                                      1
                                                                    TOTAL     9

No.                                 Mark Scheme                     Sub     Total
                                                                    Mark    Mark
 2      (a) (i)   Carbon dioxide                                     1

           (ii)   Limewater turns cloudy/milkychalky//white                   2
                  precipitate formed                                 1
         (b)      Zinc oxide                                         1        1
         (c)      ZnCO3                 ZnO + CO2
                     1. correct formula for reactant                 1
                     2. correct formula for products                 1        2

        (d) (i)
                   4
                  125     mol // 0.032 mol                           1



4541/2(PP) @ PKPSM Cawangan Pahang 2010                                           SULIT
SULIT                                                                         4541/2(PP)


           (ii)   1. Correct ratio
                     1 mole of ZnCO3 : 1 mole of CO2 //                 1
                      0.032 mole : 0.032 mole
                  2. Correct volume of gas with unit                    1       4
                     0.032 x 24 dm3 // 0.768 dm3 // 768 cm3 .

          (iii)   0.032 x 6.02 x 10 23 molecules // 1.926 x 10   22
                                                                        1
                  molecules.
                                                                      TOTAL     9
No.                                Mark Scheme                         Sub    Total
                                                                       Mark   Mark
 3      (a)       P                                                     1       1
        (b)       R                                                     1       1
        (c) (i)   The electronegativity is increase from Q to V         1

            (ii) Across the period from Q to V , the atomic size        1       3
                 decreases,
                 The attraction force between nucleus and valens        1
                 electrons increases
          (d)    R is more reactive than Q                              1       1
          (e)    Because the element has octet electron
                 arrangement/
                 Because the outermost shell has occupied 8             1       1
                 electrons.
        (f) (i) TU4                                                     1



         (ii)




                                                                                3




4541/2(PP) @ PKPSM Cawangan Pahang 2010                                             SULIT
SULIT                                                                                      4541/2(PP)


                  Corect diagram, label T and U, correct no. of electron             1
                  Correct valens electron each of the atom                           1


                                                                           TOTAL           10 M
No.                                        Mark Scheme                             Sub     Total
                                                                                   Mark    Mark
 4       (a)      1. Strong acid is the acid that is completely                     1
                  dissociated in water
                  2. produce higher concentration of hydrogen
                  ions                                                               1       2

        (b)(i)    HCl + NaOH  NaCl + H2O
                  - Correct formula of reactants                                     1
                  - Correct formula of products                                      1       2

        (b)(ii)   No. of mol of HCl = (20.00 x 0.1)/1000                             1
                                    = 0.002 mol                                      1       2

        (b)(iii) 1. From the eq., 1 mol HCl : 1 mol NaOH
                 2. Molarity of NaOH = 0.002 x 1000 /                                        3

         (c)      Colourless to pink                                                 1       1

                                                                                   TOTAL    10


No.                                         Mark Scheme                            Sub     Total
                                                                                   Mark    Mark
 5      (a)(i)    C4H9OH                                                            1       1

        (a)(ii)   1.




                                                                                    1

                  2.




                                                                                    1        2



4541/2(PP) @ PKPSM Cawangan Pahang 2010                                                          SULIT
SULIT                                                                    4541/2(PP)


        (a)(iii)   Ethyl butanoate                                 1       1

        (b)(i)     Carbon dioxide                                  1       1


        (b)(ii)    C4H10 + 13/2O2  4CO2 + 5H2O //
                   2C4H10 + 13O2  8CO2 + 10H2O
                   - Correct formula of reactants and products     1
                   - Balanced equation                             1       2

          (c)
                                                      Butene
                    Glass wool
                                     Porcelain
                    soaked with
                                     chips
                    butanol




                            Heat

                                                      Water


                   1. Functional diagram                           1
                   2. Labeled diagram                              1       2




          (d)      1. Butene is unsaturated hydrocarbon //
                      has double bond                              1
                   2. Butane is saturated hydrocarbon //
                      Has single bond                              1       2

                                                                 TOTAL    11




4541/2(PP) @ PKPSM Cawangan Pahang 2010                                        SULIT
SULIT                                                                               4541/2(PP)


No.                                      Mark Scheme                        Sub     Total
                                                                            Mark    Mark
    6          (a)      To allow the movement of ions                        1       1

          (b)(i)        Brown colour of bromine water turns colourless       1

          (b)(ii)       Green colour of iron(II) sulphate solution turns
                        brown                                                1          2

          (c)(i)        Br2 + 2e  2Br –                                     1

          (c)(ii)       0 to -1                                              1
          (c)(iii)      Reduction reaction                                   1          3

          (d)(i)        Fe2+  Fe3+ + e                                      1

          (d)(ii)       Potassium iodide solution, KI //
                        Reactive metals, e.g Zinc, Zn                        1          2

               (e)      Br2 + 2Fe2+  2Br - + 2Fe3+
                        - Correct formula of reactants and products          1          1

               (f)      Y  X                                                1          1

               (g)      Bromine water                                        1          1

                                                                           [TOTAL       11



                                               SECTION C

No                                           Mark Scheme                            Sub       Tota
 .                                                                                  Mar         l
                                                                                     k        Mar
                                                                                               k
7       (a)          Solution A: covalent                                           1
                                                                                               2
        (i)          Solution B: ionic                                              1
        (ii)            - In solution A, A exist as molecule // no free moving      1
                            ions
                        - Molecule does not carry the charge and the bulb does      1
                            not light up                                            1
                        - In solution B, ions can move freely                       1
                     Ions carry the charge and the bulb is lighted up                          4




4541/2(PP) @ PKPSM Cawangan Pahang 2010                                                      SULIT
SULIT                                                                              4541/2(PP)


    (b)                 Cell J                           Cell K
    (i)        Gas bubbles are released           Anode becomes thinner            1+
                     Gas oxygen                       Copper (II) ion              1        4
                                                                                   1+
                                                                                   1
    (b)(ii   Cell J : 4OH-  O2 + 2H2O + 4e                                        1        2
    )        Cell K : Mg  Mg2+ + 2e                                               1
    (c)



                                                       Carbon electrodes


             Potassium iodide                          Acidified potassium
             solution                                  manganate (VII) solution



                                                     Dilute sulphuric acid

                -    correct functional diagram                                    1        2
                -    label                                                         1

    (d)
    (i)      - potassium iodide solution : colourless solution turns brown         1
             - acidified potassium manganate (VII) solution : purple
             solution decolourised                                                 1

    (ii)     potassium iodide solution : 2I-  I2 + 2e                             1
             acidified potassium manganate (VII) solution :                                 6
             MnO4- + 8H+ + 5e  Mn2+ + 4H2O                                        1

    (iii)    To allow the flow of ions from both electrolytes // to separate       1
             the reducing agent from the oxidising agent.

     (iv)    Potassium nitrate solution // sodium chloride chloride solution       1
             // potassium sulphate solution [any suitable answer]

                                                                                  TOTAL     20




4541/2(PP) @ PKPSM Cawangan Pahang 2010                                                   SULIT
SULIT                                                                        4541/2(PP)


No.                             Mark Scheme                           Sub    Total
                                                                      Mark   Mark
 8      (a)   [Able to classify the type of food additives in
              given situation correctly]

                   Food          Substance
                  additive
               Colouring        Tartazine                              1      4
               Flavouring       Octyl                                  1
                                ethanoate
               Anti oxidant     Citric acid                            1
               Sweetener//      aspartame
               preservative                                            1


        (b)   Antibiotic                                               1

              1.To make sure all the bacteria are killed               1      5

                Otherwise the patient may becomes ill again            1

                Bacteria become more resistant to the                  1
                antibiotic.

                As a result, the antibiotic is no longer
               effective.// Patients need stronger antibiotic to       1
               fight the same infection

        (c)   Part X – hydrophobic/hydrocarbon                         4      4
              Part Y – hydrophilic/ionic
              Parx X – dissolves in grease
              Part Y – dissolves in water

        (c)   1.The cloth in experiment II is clean                    1
                 whereas the cloth in Experiment I is still dirty.     1
              2.In hard water,soap react with magnesium ion            1
              3.to form scum                                           1
              4.Detergent are more effective in hard water             1      7
              5.Detergent does not form scum                           1
              6.Detergent are better cleansing agen then soap
                to remove oily stain.                                  1

                                                                     TOTAL   20 M




4541/2(PP) @ PKPSM Cawangan Pahang 2010                                              SULIT
SULIT                                                                          4541/2(PP)


No.                                  Mark Scheme                        Sub    Total
                                                                        Mark   Mark
9       (a)       Rate of reaction is the speed at which reactants
                  are converted into products in a chemical             1      1
                  reaction.
        (b)       30      = 0.25 cm3s-1
        (i)       2x 60                                                 1

                  45        = 0.375 / 0.38 cm3s-1
        (ii)      2x 60                                                 1      3

                  15        = 0.125 / 0.13 cm3s-1
          (iii)   2x 60                                                 1

        (c)       CaCO3 + H2SO4  CaSO4 + CO2 + H2 O
        (i)
                  Reactant and product correct                          1
                                                                               2
                  Balance equation                                      1


        (ii)      The number of moles CaCO3 = 0.2/40 + 12 +
                  (16x3)
                                            = 0.002 mol                 1

                  1 mole of CaCO3 releases 1 mole of CO2 . (ratio       1
                  of CaCO3 to CO2 )
                  0.002 mole of CaCO3 releases 0.002 mole of            1      4
                  CO2
                  The maximum volume of CO2 = 0.002 x 22.4
                                              = 0.0448 dm3              1
                                              = 44.8 cm3

        (d)         -     Experiment II has a higher rate of reaction
        (i)               compared to experiment I                      1
                    -     The concentration of sulphuric acid,
                          H2SO4 in experiment II is higher than         1
                          experiment I
                    -     When the concentration of the solution is
                          increase/higher, the number of reactant
                          particles also increase/higher.               1
                    -     The frequency of collision between
                          carbonate ions and hydrogen ions              1          5
                          increases
                    -     The frequency of effective collision also     1
                          increases


4541/2(PP) @ PKPSM Cawangan Pahang 2010                                                SULIT
SULIT                                                                       4541/2(PP)


        (d)       -   Experiment I has a higher rate of reaction
        (ii)          compared to experiment III                    1
                  -   The temperature used in experiment I is
                      higher than in experiment III                 1
                  -   Higher temperature causes particles
                      move faster/higher//kinetic energy is         1
                      increase
                  -   Frequency of collision between carbonate                  5
                      ions and hydrogen ions increase               1
                  -   The frequency of effective collision also
                      increases                                     1

                                                                    TOTAL       20

No.                              Mark Scheme                          Sub   Total
                                                                     Mark   Mark
 10     (a)     Blue solution X = Copper (II) sulphate              1
        (i)     Colurless solution Y = potassium carbonate //
                sodium carbonate // ammonium carbonate              1       2

        (ii)    Double decomposition method                         1       1

        (iii)   CuSO4 + K2CO3  CuCO3 + K2SO4 //

                CuSO4 + Na2CO3  CuCO3 + Na2SO4 //

                CuSO4 + (NH4 )2CO3  CuCO3 + (NH4 )2SO4

                Correct rectants and products                       1
                Balanced equations                                  1       2

        (iv)      -   Add sodium hydroxide solution (until          1
                      excess)                                       1       2
                  - Blue precipitate formed
                      //
                  - Add ammonia aqueous / ammonium
                      hydroxide solution (until excess)
                Blue precipitate soluble in excess
        (b)     Copper (II) oxide                                       1       1
        (i)
        (ii)    Materials : [25 – 100] cm3 of [0.5 – 2.0] moldm-3   1
                copper (II)sulphate solution(any suitable
                answer) [25 – 100] cm3 of [0.5 – 2.0] moldm-3       1
                sodium carbonate solution
                 (any suitable answer) Filter paper                 1
                Apparatus : Filter funnel, beakers, retort stand    1


4541/2(PP) @ PKPSM Cawangan Pahang 2010                                              SULIT
SULIT                                                                        4541/2(PP)


                and clamp, glass rod and 100cm3 measuring
                cylinder.

                Procedures :

                  -   About [25 – 100] cm3 of [0.5 – 2.0] moldm-     1
                      3
                         copper (II) sulphate solution is measured
                      into a beaker.
                  -   About [25 – 100] cm3 of [0.5 – 2.0] moldm-
                      3
                         sodium carbonate solution is measured       1
                      and mixed with the solution in the beaker.
                  -   The mixture is stirred with a glass rod.       1
                  -   The precipitate formed is removed by                   10
                      filtration.                                    1
                  -   The precipitate is rinsed with distilled
                      water.                                         1
                  -   The precipitate is dried between the filter
                      paper                                          1

        (iii)   2AgNO3 + MgCl2  2AgCl + Mg(NO3)2

                No of moles AgNO3 = 50 x 1.0 / 1000 = 0.05               1
                mol
                                                                                  2
                2 mol AgNO3  2 mol AgCl from the reaction
                0.05 mol AgNO3  0.05 mol AgCl

                Mass of AgCl = 0.05 x 143.5                              1
                             = 7.175 g
                                                                     TOTAL    20




4541/2(PP) @ PKPSM Cawangan Pahang 2010                                               SULIT

				
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