SKEMA JAWAPAN KERTAS (454/) PERCUBAAN SPM 06 MARKING SCHEME OF PAPER (454/) SPM TRIAL 06 QUESTION RUBRIC MARKS (a) (i) W and X/X and Y/W and Y (any one answer) (ii) The elements have the same number of electron shells (b) (i) Element Y (ii) The atoms of element Y does not gain, release or share electrons Atomic size of Z is bigger than of W. Z is more reactive than W. (d) (i) V (ii).can be used as a catalyst.have variable oxidation states. 3.Able to form complex ions. (Any one answer) TOTAL 9 QUESTION RUBRIC MARKS (a) To clean the surface of magnesium ribbon from oxides layer (b) (i) Magnesium:0.3g Oxygen:0.g (ii) Moles : Mass/ Relative Atomic Mass Magnesium: 0.3g/4:0.05 mol Oxygen:0.05 mol Ratio of moles of magnesium to oxygen is : (iii) MgO Mg + O MgO (d) TOTAL 9
QUESTION RUBRIC MARKS 3(a) Antioxidant (b) Helps to mix the fats and water during the manufacturing process Flavouring agent It is ester (d) Aspartame (e) (i) M (ii) Skin disease (iii) The extract of its leaves is applied on the affected area (f) (i) May cause bleeding in the stomach (ii) So that all the bacteria that cause disease are killed TOTAL 0 QUESTION RUBRIC MARK 4(a) H H I I H - C - C - OH I I H H (b) Brown colour of bromin water dicolourised Warna perang bromin dilunturkan Susunan radas betul Label : kapas kaca, etanol, serpihan porselin/pasu berliang (d) Polimerisation (e) Have acidic properties (f) Food flavouring / food additives / ester (g) (i) Bacteria in latex produced an acid Ion H + from asid neutralized the negatively charged of protein membrane Membrane protein of latex breaks when collides between
each other Molecules of latex combine and coagulate (mana-mana jawapan yang betul) (ii) Add alkaline solution / ammonium solution TOTAL 0 QUESTION RUBRIC MARK 5 a Lead(II)carbonate b (i) Lead(II)oxide (ii) Brown when hot, yellow when cool c (i) Bubbles of gas or effervescence is present (ii) Lead (II)nitrate (iii) A white precipitate is formed that is soluble in excess sodium hydroxide solution d (i) Lead (II) iodide (ii) Pb + (aq) + I ( aq) PbI TOTAL QUESTION RUBRIC MARK 6 a To allow the transfer of ions b c Colourless to brown Add starch solution, dark blue precipitate is formed d Manganate (VII) ion Manganate (VII) ion receives the electron e (i) MnO 4 - + 8H + + 5e Mn + + 4 H O (ii) Brown solution turns colourless +7 + Total 3
QUESTION RUBRIC MARK 7 (a) (i) X and Y or Y and Z (ii) X and X (b) COMPOUND P Atom Y has an electron arrangement of.8.. Atom Y donates one valence electron to achieve the stable octet electron arrangement and form Y + ion. Atom Z has an electron arrangement of.8.7. Atom Z receives one electron to achieve the stable octet electron arrangement and form Z - ion. Y + and Z - ions are attracted to each other to form the ionic bond. COMPOUND Q Atom U has an electron arrangement of.6. Atom U needs two electrons. to achieve the stable octet electron arrangement. Two U atoms share two pairs of electrons to form a double covalent bond COMPOUND P Can conduct electricity in molten or aqueous state In these forms, the ions in the compounds are free moving which allows it to conduct electricity COMPOUND Q Does not conduct electricity in any form They do not have free moving ions. Neutral molecules cannot conduct electricity. + + TOTAL 0 4
QUESTION RUBRIC MARK 8 (a) (i) Mg + HCl MgCl + H NOM of HCl = 5 x / 000 = 0.05 mol From the equation: mol of HCl = mol of H 0.05 0f HCl = 0.05/ = 0.05 mol Volume of H = 0.05 x 4 = 0.3 dm 3 = 300 cm 3 (b) The time taken for experiment II is shorter. This implies that the reaction for Experiment II is faster. Thus copper (II) sulphate acts as the catalyst If a catalyst is added, the rate of reaction increases. The catalyst provides an alternative route with lower activation energy for the reaction to occur. Hence, the minimum energy required for the reaction is less or more reacting particles possess sufficient energy to overcome the lower activation energy required for effective collisions. As a result, the frequency of effective collision increases and the rate of reaction increases. Energy profile diagram 4 5
The energy level of the reactants is higher than that of the products. This shows that some energy is released or the reaction is an exothermic reaction. This difference in energy between the reactants and the product is known as the heat of reaction. The difference in energy between the energy of the reactants and the minimum energy of the curve is the activation energy. It is the energy barrier that must be overcome for the reaction to occur. When a positive catalyst is used in a chemical reaction, the reaction occurs through an alternative path which required lower activation energy. As a result,more colliding particles are able to overcome this lower activation energy and the rate of reaction increases. TOTAL 0 QUESTION RUBRIC MARK 9(a) Reaction I is Exothemic// release heat to the surroundings Reaction II is Endothermic// absorb heat from the surroundings. The total energy content of mole of silver nitrate and mole of sodium chloride is higher than the total energy content of mole of silver chloride and mole of sodium nitrate in reaction I. The total energy content of mole nitrogen and mole of oxygen is lower than the total energy content of mole of nitrogen dioxide in reaction II. (b) (i) As the number of carbon and hydrogen atoms per molecule increases, the value of heat combustion increases. The higher the number of carbon and hydrogen atoms per molecule, the more carbon dioxide and water molecule as products will be formed. More bonds in the product formed, more heat is released. 6
(ii). Stir the water continuously. Use a windshield 3. Do not use wire gauze 4. Make sure the flame touches the bottom of the metal can (Any three) 3 (i). Zinc/ Magnesium/ Any suitable metal. Copper (II) sulphate solution/ silver nitrate solution [Any suitable solution] 3. Measure [0-00 cm 3 ] of [0.- mol dm -3 ] copper(ii) sulphate/ any suitable solution and pour into copper (II) sulphate solution. 4. Record initial temperature of copper (II) sulphate solution. 5. Add excess zinc/magnesium powder into copper (II) sulphate solution 6. Stir the mixture 7. Record highest temperature Calculation 8. No of mole of CuSO 4 = [0.5 x 0] // 0.0 000 9. H = 0 x C x θ J 0. H = -(0xCxθ) kj mol - // -z kj mol - 0.0 000 0 TOTAL 0 7
QUESTION RUBRIC MARK 0(a) (i) Titration number Trial 3 Initial burette reading/ cm 3 Final burette reading/ cm 3 Volume of sulphuric acid/ cm 3 Average volume of sulphuric acid/ cm 3 3 (ii) The physical state of sodium sulphate is wrong The chemical formula of sodium sulphate is wrong The chemical equation is not balanced Correct chemical equation: H SO 4 (aq) + NaOH(aq) Na SO 4 (aq) + H O(l) (b) (i) 3 (ii) M a V a M b V b = M a 7.50 30.00 0.70 = M a =.40 mol dm 3. Number of mol of NaOH 0.70 400.00 = 000 = 0.8 mol Mass of NaOH = 0.8 (3 + 6 + ) =. g 8
. Weigh 4 g of sodium hydroxide. 3. Dissolve the sodium hydroxide in distilled water in a beaker. 4. Pour the solution into a 500 cm 3 volumetric flask. 5. Using a wash bottle, rinse the weighing bottle, filter funnel and beaker with distilled water and wash down into the volumetric flask. 6. Remove the filter funnel and add distilled water into the volumetric flask until the meniscus level is at the calibration mark. 7. Stopper the volumetric flask and shake gently. TOTAL 0 9