ujian pengesanan pertengahan tahun 2009_mark scheme chemistry 3

7/31/2019 Ujian Pengesanan Pertengahan Tahun 2009_Mark Scheme Chemistry 3

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SULIT

4541/3

Chemistry

Paper 3

May

1 1/2 hours

JABATAN PELAJARAN MELAKA

____________________________________________________________

UJIAN PENGESANAN PERTENGAHAN TAHUN

SIJIL PELAJARAN MALAYSIA 2009

CHEMISTRY

Paper 3

One hour and thirthy minutes

MARKING SCHEME


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Question Rubric Score

1 (a) (i) Able to record all readings accurately to one decimal pointwith

unit

Sample answer:Set I: 55.0s Set II: 48.0s Set III: 42.0s

Set IV: 37.0s Set V: 33.0s

3

Able to record all readings correctlywithout unit / withoutdecimal point

Sample answer:

Set I: 55.0 / 55s Set II: 48.0 / 48s Set III: 42.0 / 42s

Set IV: 37.0 / 37s Set V: 33.0 / 33s

2

Able to recordthree readings correctly

Sample answer:

Set I: 55 Set II: 45.6 Set III: 42Set IV: 37 Set V: 30.6

1

No response or wrong response 0

1 (a) (ii) Able to construct a table that contain:

1 Correct titles2 Readings and units

Sample answer

Set Temperature / 0C Time taken / s

I 30.0 55.0

II 35.0 48.0

III 40.0 42.0

IV 45.0 37.0

V 50.0 33.0

Note : ecf for the time taken for Set I to Set V

3

Able to construct a less accurate table that contain:

1 Titles

2 Readings without unit 2

2


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Sample answer

Temperature Time taken

Set I 30.0 55.0Set II 35.0 48.0

Set III 40.0 42.0

Set IV 45.0 37.0

Set V 50.0 33.0

Able to construct a table with at leasttwo title

Sample answer

Temperature Time taken30 55

35 48

40 42

45 37

50 33

1


1 (b) Able to give the relationship accurately and state the direction.

Sample answer:

The higher the temperature, the shorter the time taken formagnesium ribbon to completely dissolved.

3

Able to give the relationship correctly without state the direction

Sample answer:

Temperature affects time taken for magnesium ribbon to

completely dissolve.

2

Able to give an idea of the relationship

Sample answer:

Time for magnesium ribbon to dissolve become shorter

1

3


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1 (c) Able to state all three variables correctly

Sample answer:Manipulated variable: Temperature

Responding variable: Time taken

Constant variable: Concentration & volume of

hydrochloric acid // length ofmagnesium ribbon

3

Able to state any two variables correctly 2

Able to state any one variables correctly 1


1 (d) Able to give accurate reading ( 37.0s < X < 42.0s) to onedecimal point with unit

Sample answer:38.0s // 39.0s // 40.0s // 41.0s

3

Able to give correct reading without decimal point / unit

Sample answer:

38s // 39.0 // 40s // 41.0

2

Able to give range of reading without decimal point / unit

Sample answer:

(37.0 < X < 42.0)

1


2 (a) Able to draw a graph of the height of precipitate against volume

of potassium chromate(VI) by showing the following information

i. The axes are labeled correctly with unit

ii. Uniform scale & size of the graph at least 50% of the

3

4


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graph paper

iii. All points are transferred correctly

Able to draw a graph of the height of precipitate against volume


i. The axes are labeled correctly without unit

ii. All points are transferred correctly

2

Able to draw a graph of the height of precipitate against volume


i. The axes are labeled correctly without unit

ii. Curve / straight line on the graph

1


2 (b) Able to state the observation correctly

Sample answer:

The height of the precipitate increases from test tube 1 to test tube4 and become constant from test tube 5 to test tube 7.

3

Able to state the observation incompletely.

Sample answer:The height of the precipitate increases and then become constant

2

Able to state an idea of the observation

Sample answer:

The height of the precipitate increases.

1


2 (c) Able to state the inference correctly

Sample answer:

The reaction has been completed at test tube 5 because the heightof precipitate becomes constant from test tube 5 to test tube 7.

3

Able to state the inference incompletely.

Sample answer:The reaction has been completed when the height of precipitate

becomes constant.

2

5


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Able to state an idea of inference.

Sample answer:

The reaction has been completed at test tube 5

1


2 (d) Able to state the relationship correctly between the manipulated

variable and the responding variable with direction.

Sample answer:

As the volume of potassium chromate(VI) increased, the height ofthe precipitate increase until it achieves a maximum height.

3

Able to state the relationship between the manipulated variableand the responding variable with direction.

Sample answer:When the volume of potassium chromate(VI) increased, the

height of the precipitate also increase.

2

Able to state the idea of hypothesis.

Sample answer:

The height of the precipitate increase.

1


2 (e) Able to state the correct operational definition for continuous

variation method correctly.

Sample answer:

The height of precipitate formed will increased and remainconstant when a fix volume of lead(II) nitrate solution is added

with potassium chromate(VI) solution.

3

Able to state the meaning of continuous variation method

incompletely.

Sample answer:

The height of precipitate formed will increased and remain

constant when lead(II) nitrate solution is added with potassiumchromate(VI) solution.

2

6


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Able to state an idea of continuous variation method.

Sample answer:

Precipitate will formed when lead(II) nitrate solution is addedwith potassium chromate(VI) solution.

1


2 (f) Able to classify all the sixions correctly.

Sample answer:

Positive ion / Cation Negative ion / Anion

Pb2+ NO3-

K+

I-

H+ OH-

3

Able to classify any four ions correctly.

Sample answer:


Pb2+ NO3-

K+ I-

2

Able to classify any two ions correctly.

Sample answer:


Pb2+ I-

NO3+ K-

1


3 (i) Able to give the statement of the problem accurately by relating

the following four information:i. Position / distance

ii. Pair of metals // two metals

iii. Electrochemical series (ECS)

iv. Voltage

Sample answer:

How does position between two metals in the Electrochemical

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Series affect the voltage?

Able to give the statement of the problem correctly by mention

i. position / distance // pair of metal

ii. ECS / Reactivity Seriesiii. Voltage

Sample answer:

Does the position of metals in ECS affect the voltage? //Does the position of electrode in Reactivity Series affect the

voltage? //

Does the distance of metals in ECS affect the voltage

2

Able to give an idea of statement of the problem correctly

Sample answer:Metals/electrode produces voltage.

1


3 (ii) Able to state all three variables correctly

Sample answer:

Manipulated variable: pairs of metals // two electrodesResponding variable: Voltage // voltmeter reading //

potential differenceConstant variable: Electrolyte // volume &

concentration of electrolyte //

metal as the positive / negativeterminal

3

Able to state any two variables correctly 2

Able to state any one variables correctly 1


8


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3 (iii)

Able to state the relationship between the manipulated variableand the responding variable and state the direction

Sample answer:The further / nearer the distance of the two metals in

Electrochemical Series, the bigger / smaller the voltage.

3

Able to state the relationship between the manipulated variableand the responding variable without stating the direction

Sample answer:

The distance between metals in ECS affect the voltmeter reading

2

Able to state the idea of hypothesis correctly

Sample answer:

Different metal produces different voltage

1


3 (iv) Able to give complete list of substances and apparatusi. At least three metal below Ca in ECS

ii. Voltmeter

iii. Electrolyte, beaker, wire, sand paper

Sample answer:

Aluminium, zinc, copper, voltmeter, copper(II) sulphate solution,

beaker, connecting wires, sand paper

3

Able to state the following thingsi. At least two metal below Ca in ECS

ii. Voltmeter

iii. Electrolyte, container

Sample answer:Zinc, copper, voltmeter, copper(II) sulphate solution, beaker,

2

Able to state the following things

i. two metalsii. electrolyte

Sample answer:

1

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Aluminium, zinc, sodium hydroxide solution


3 (v) Able to state the following six steps

1. Add/pour the electrolyte into a container2. Clean the metal strip with sandpaper

3. Dip both metals into the electrolyte

4. Connect the metals to the voltmeter// complete the circuit

5. Record the voltmeter reading6. Repeat step 1-5 by substituting one metal for another

3

Step 1 or 3, 4, 5, 6 2

Step 1 or 3 1


3 (vi) Able to exhibit the tabulation of data that includes the following

information:

1. Heading for manipulated variable

2. Heading for the responding variable with unit3. Examples of two pairs of metals

Sample answer:

Pair of metals Voltage / V

Zinc and copper

Iron and copper

3

Able to exhibit the tabulation of data that includes the following

information:1. Heading for manipulated variable

2. Heading for the responding variable without unit

3. Examples of one pairs of metals

2

10


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Sample answer:

Pair of metals Voltage

Zinc and copper

Able to exhibit the tabulation of data that includes the following

information:

Heading for the (manipulated variable) / (responding

variable without unit)

Sample answer:

Pair of metals

1


END OF MARK SCHEME

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ujian pengesanan pertengahan tahun 2009_mark scheme chemistry 3

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