kesilapan umum kimia kertas 2 bhg c.docx

8/10/2019 kesilapan umum kimia kertas 2 bhg C.docx

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Common Mistakes for SPM Chemistry Paper 2

Section C

Students need to answer any one question from this section C (experimental

essay). The SPM questions in Paper 2 Section C (Question 9 & 10) consist of20 marks in total. The Johor state SPM 2010 trial paper 2 (Section C

Question number 9 and 10) is used in the following discussion.

1) Is it a compulsory to draw experimental diagram?

No. It is not compulsory to draw experimental diagram unless it is stated in

the question.

i.e. By using a suitable diagram, explain a laboratory experiment to

determine

I would recommend that even the question not stated this statement, it is

better for the students to draw the diagram because it will help you in

remembering the important apparatus and material which is being used in

the experiment. Besides that, you need to label (apparatus and material) the

experimental diagram.

2) What are the techniques in writing these procedures?

Each sentence or procedure step must have this combination to form a

sentence.

Subject (material or apparatus) + verb + object (material or apparatus).

3) How to write procedure of the experiment?

Students are always confused with whether to use active formed sentence or

passive formed sentence. The answer is no penalty but students can choose

only one form. It is different from the PEKA experiments procedure which

must be in passive form sentence. So I would usually recommend my students

to write passive form sentence (past perfect tense) in PEKA experiments and

experimental essay (Section C).

Example 1

Using a suitable example, describe a laboratory experiment to determine the

empirical formula of an oxide of a reactive metal. Your explanation should

include: procedure of the experiment (Dengan menggunakan contoh yang


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sesuai, huraikan suatu experimen di makmal untuk menentukan formula

empiric bagi suatu oksida logam reaktif. Penerangan anda mestilah meliputi:

prosedur bagi eksperimen) Q9 (c) (iii)

Correct answer candidate A (passive formpast perfect tense):

1.5 cm of magnesium ribbon was cleaned with sandpaper to remove the oxide

layer.

2.

An empty crucible and its lid were weighed using electronic balance and its

mass was recorded.

3.The coiled magnesium ribbon was placed in the crucible.

4.The crucible, crucible lid and magnesium ribbon were weighed and its mass

was recorded.

5.

Correct answer candidate B (passive formpresent perfect tense):

1.5 cm of magnesium ribbon is cleaned with sandpaper to remove the oxide

layer.

2.An empty crucible and its lid are weighed using electronic balance and its

mass was recorded.

3.The coiled magnesium ribbon is placed in the crucible.

4.The crucible, crucible lid and magnesium ribbon are weighed and its mass

is recorded

5.

But for those students who are very weak in English language, I would

recommend you to write in active form sentence (present tense).

Correct answer candidate C (active form):

1.Clean 5 cm magnesium ribbon with sandpaper.

2.

Coil magnesium ribbon.

3.Weigh an empty crucible with its lid.

4.Record the reading.

5.

Place the magnesium in the crucible and weigh again.6.

Record the reading.

4) Is it a compulsory to give example for the experiment?

Yes. Students need to give an example of the material.

Example 2


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Using a suitable example, describe a laboratory experiment to determine the

empirical formula of an oxide of a reactive metal. (Dengan menggunakan

contoh yang sesuai, huraikan suatu experimen di makmal untuk menentukan

formula empiric bagi suatu oksida logam reaktif.)

Procedure of the experiment (Prosedur bagi eksperimen) Tabulation of data (Penjadualan data) Q9 (c) (iii)

Wrong answer:

1.5cm metal ribbon was cleaned with sandpaper.

2.

Description Mass (g)

Crucible + lid

Crucible + lid + metal

Crucible + lid + metal oxideCorrect answer:

1.5 cm of magnesium ribbon was cleaned with sandpaper.

2.

Description Mass (g)

Crucible + lid

Crucible + lid + magnesium

Crucible + lid + magnesium oxide

(Students do not need to include the value of mass unless it is given in the

question.)

kesilapan umum kimia kertas 2 bhg c.docx

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