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PEJABAT PELAJARAN DAERAH JOHOR BAHRU_____________________________________________________

PEPERIKSAAN AKHIR TAHUN 2011TINGKATAN EMPAT Chemistry Kertas 3 Peraturan Pemarkahan Oktober 2011

4541/3 (PP)

UNTUK KEGUNAAN PEMERIKSA SAHAJA

AMARAN Peraturan pemarkahan ini SULIT dan Hak Cipta JKD Kimia Daerah Johor Bahru. Kegunaannya khusus untuk pemeriksa yang berkenaan sahaja. Sebarang maklumat dalam peraturan pemarkahan ini tidak boleh dimaklumkan kepada sesiapa. Peraturan pemarkahan ini tidak boleh dikeluarkan dalam apa-apa bentuk media.

___________________________________________________________________________ Peraturan pemarkahan ini mengandungi 9 halaman bercetak

2 Question Rubric Score

3 1 (a) Able to give the observations and relevant inference of the experiment. Sample answer: Observations (i) White fume is released. (ii) (iii) White solid is formed. The mass of crucible and its content increases Inference (i) Magnesium reacts with oxygen. (ii) Magnesium oxide is formed. (iii) Magnesium oxide is formed. 6

The inference must relevant to observation stated. 5 4 3 2 1 0 3

Able to give any five of the observations and relevant inference of the experiment. Able to give any four of the observations and relevant inference of the experiment. Able to give any three of the observations and relevant inference of the experiment. Able to give any two of the observations and relevant inference of the experiment. Able to give any one of the observations of the experiment. No response or wrong response 1(b) Able to record the readings to two decimal places correctly. Sample answer: The mass of crucible and lid = 25.35g The mass of crucible, lid and magnesium ribbon = 27.75g The mass of crucible, lid and magnesium oxide when cooled = 29.35g Able to record any two of the readings to two decimal places correctly. Able to record any one of the readings to two decimal places correctly. No response or wrong response

2 1 0

1(c)

Able to

3

4 calculate the mass of magnesium and oxygen with unit by showing the methods used write the ratio of Mg : O correctly.

Sample answer: (i) The mass of magnesium = (27.75 25.35)g = 2.4g (ii) (iii) The mass of oxygen = (29.35 27.75)g = 1.6g The number of mole of Mg = 2.4 / 24 = 0.1 mol The number of mole of O = 1.6/16 = 0.1 mol Able to calculate any two from 1(c) without unit. Able to calculate any one from 1(c) without unit. No response or wrong response. 1(d) Able to write the empirical formula of magnesium oxide by showing the methods. Sample answer: The ratio of Mg : O = 0.1 : 0.1 =1:1 The empirical formula is MgO. Able to write the empirical formula of magnesium oxide without showing the methods. Sample answer: The empirical formula is MgO. Sample answer: MgO No response or wrong response. 1(e) Able to state three precaution steps correctly. Sample answer: 1. Cover the crucible with its lid when the magnesium ribbon starts to burn. 2. Raise the lid a little, at intervals. 3. Repeat the procee of heating, cooling and weighing until a 1 0 3 2 2 1 0 3

5 constant mass is obtained. Able to state two precaution steps correctly. Able to state one precaution step correctly. No response or wrong response. 2(a) Able to state the observation that shows the change in colour in the experiment correctly. Sample answer: 1. Blue solution is fading in colour. 2. Blue solution becomes light blue. 3. The density of the blue colour is reduced. Able to state the observation at the end of the experiment. Sample answer: 1. Light blue solution is form. 2. The density of the colour is reduced. 3. The colour of solution is faded. 4. The blue colour of solution is reduced. Able to state the correct colour but without intensity. Sample answer: 1. Solution is colourless. 2. Solution is blue. 3. The colour of solution decolourised. No response or wrong response. 2(b) Able to state three variables and the way to control them correctly. Sample answer: Manipulated variable: Pair of metals / Pair of electrode / Negative electrode Responding variable: Reading of voltmeter / Reflexion of voltmeter needle / voltage Controlled variable: - Type of electrolyte / Copper (II) sulphate solution Method to manipulated the variable: Use different pair of metals / Substituting the negative electrode How the variable is responding: The reading / voltage of voltmeter changes/ increases / decreases Method to maintain the controlled variable: - Use the same type of electrolyte 0 6 1 2 2 1 0 3

6 - Concentration of electrolyte / same - Voltmeter - Copper electrode / Positive electrode - Maintain the same concentration of electrolyte - Use the same voltmeter - Maintain the type of positive electrode / Maintain copper electrode as positive electrode 5 4 3 2 1 0 3

Able to state any 5 of the above informations correctly. Able to state any 4 of the above informations correctly. Able to state any 3 of the above informations correctly. Able to state any 2 of the above informations correctly. Able to state any 1 of the above informations correctly. No response or wrong response. 2(c) Able to state the relationship between the manipulated variable and the responding variable correctly and with direction. Sample answer: 1. The further apart / nearer the position of the pair of metals in Electrochemical Series, the higher / lower is the voltage value. Hypothesis can be positive or negative statement. If responding variable is sated before manipulated variable, score 2. If Reactivity Series is stated, score 1.

Able to state the relationship between the manipulated variable and the responding variable correctly and without direction. Sample answer:2. The position of metals in Electrochemical Series affects the

2

voltage value / voltmeter reading . Able to state an idea of the hypothesis. Sample answer: 1. voltage value. 2. 3. in The Electrochemical Series is determined by the Different metals give different voltage value. Voltmeter reading affects the position of metals 1

7 Electrochemical Series. No response or wrong response. 2(d) Able to classify the ions into cation and anion correctly. Sample answer: Cation : Cu2+ , H+ Anion : SO42-, OHAble to classify the ions into cation and anion with minimum 3 ions classified correctly or classify the ions without the title of classification. Sample answer:2. Cation : Cu2+ , H+

0 3

2

Anion : SO422. Cu2+ , H+ SO42-, OHAble to classify the ions into cation and anion with minimum 2 ions classified correctly or only give the title of classification. Sample answer:2. Cation : Cu2+

1

Anion : SO422. Cation No answer) Anion : ( No answer) No response or wrong response. Question 3(a) Rubric Able to give the statement of the problem accurately. Sample answer: How does the reactivity of lithium, sodium and potassium change when they react with water? How does the reactivity of Group 1 metals change when they react with water? Able to give the statement of the problem correctly. Sample answer: How does the reactivity of the three elements change when they react 2 0 Score 3

8 with water? Able to give an idea of statement of the problem correctly Sample answer: To compare the reactivity of these three elements towards water. No response or wrong response 0 1

Question 3(b)

Rubric Able to state all three variables correctly Sample answer: Manipulated variable : Responding variable : Constant variable : Group 1 elements// alkali metals // Li, Na, K Reactivity of metals// speed of movement// intensity of flame Size of metals // water // volume of water

Score 3

Able to state any two variables correctly Able to state any one variables correctly No response or wrong response

2 1 0

Question 3(c)

Rubric Able to state the relationship correctly between the manipulated variable and the responding variable with direction accurately. Sample answer: The lower/ higher the position of metal in Group 1, the more/ less reactive is the metal in reaction with water.// Potassium is more reactive than sodium and lithium. Able to state the relationship between the manipulated variable and the responding variable with direction correctly. Sample answer: The lower/ higher the position of metal in Group 1, the more/ less reactive is the metal.// The reactivity increases/ decreases when going down/ up Group 1.//

Score 3

2

9 The reactivity of metals depends on different type of alkali metals. Able to state any idea of the hypothesis. Sample answer: Reactivity of metal depends on the metal. // Potassium is most reactive metal.// Potassium is more reactive than sodium and lithium. No response or wrong response 0

1

Question 3(d)

Rubric Able to give complete list of substances and apparatus Sample answer: Substances: Lithium, sodium, potassium, water Apparatus: filter paper, small knife, forceps, water trough If beakeris used, score 2

Score 3

Able to list at least 2 substances and 2 apparatus correctly. Able to list at least 1 substances and 1 apparatus correctly. No response or wrong response

2 1 0

Question 3(e)

Rubric Able to state the following five steps correctly 1. 2. 3. 4. Fill the water trough with water. Cut a piece of lithium using a knife and forceps. Dry the oil on the surface of the lithium with filter paper. Place/ Drop/ Put the lithium slowly on the water surface in a trough using forceps. 5. Record the observation in the table. 6. Repeat steps 1-5 using sodium and potassium. Able to list down step 2, 4 and 6. Able to give idea for step 4. No response or wrong response

Score 3

2 1 0

10

Question 3(f) Able to tabulate the data with the 1. Correct titles 2. Complete list of elements Sample answer: Elements Lithium Sodium Potassium Able to c