STPM Chemistry 2011 – Extra Tips and Predictions for Paper 962/2: Answering Techniques (Part 1)

by BerryBerryTeacher

in Berry Super Tips *SPM/STPM

STPM chemistry extra answering techniques from Berry Berry Easy for paper 2 (Paper 962/2) is out. Here, we have a 4-part series with this Part 1 all about concepts, emerging trends, questions relating to experiment laboratory and numerical questions answers. For the numerical answers, Berry Readers will be briefed on data from questions, decimal points, data from questions, concept, significant figures and units.

STPM Chemistry 2011 – Extra Tips and Predictions for Paper 962/2: Answering Techniques (Part 1)

Berry Berry Teacher attended a talk – Form 6 Answering Techniques for STPM (Ceramah Teknik Menjawab Soalan STPM Kimia) gave by Hjh. Zainah binti Zainal from Majlis Peperiksaan Malaysia (MPM) on 23rd of October 2011 (Sunday) at Tingkat 6 Bangunan Baru Jabatan Pelajaran Negeri Johor (JPNJ). It was a two hours talk attended by 8 Form 6 teachers and 30 students from Johor Bahru, Segamat, Pasir Gudang, Muar and Batu Pahat district in Johor state.

It has started with the Johor State Chemistry Achievement in STPM analysis from 2006 until 2010.

Year A A- B+ B B- C+ C Lulus Penuh Gagal Bil. Hadir
2006 42 78 96 138 173 243 355 1125 (71.98%) 93 1563
2007 62 87 138 138 231 261 321 1238 (72.57%) 152 1706
2008 34 40 109 125 145 174 194 821

(74.84%)

82 1097
2009 60 52 89 1265 171 159 202 859 (73.42%) 83 1170
2010 81 85 106 159 157 192 201 981 (78.17%) 89 1255

Puan Hjh. Zainah binti Zainal has also given a clear clarification of the STPM examination procedure and marking scheme. STPM papers are marked by mostly veteran Form 6 teachers from various states and there is a bench-marking system in STPM examination.

Concept

1. Electronic configuration

  • Answer: 1s2 2s2 2p5
  • Wrong response: 2.7 (this is for Form 5 only)

2. Electrochemistry

  • Answer: Redox of H2O (aqueous electrochemistry – Data Booklet)
  • Wrong response: H+ and OH-

3. Answer should be in point form or essay?

  • Answer: Essay (must be in a complete sentence). Students can use table but make sure every sentence must be in a complete sentence.
  • Wrong response: Point form

4. Can students use Bahasa Melayu or English and Bahasa Melayu to answer STPM Chemistry?

  • Recommended answer: English
  • Answer: Examiners accept Bahasa Melayu answer or English combine with Bahasa Melayu answer.

5. Students must use correct term. Example: Which one is correct: half-full (d5) and partially-occupied (d3)?

  • Answer: All wrong. Correct answer: half-filled (d5) and partially-filled (d3)

6. Can students answer more than 4 questions in Section B (962/2)?

  • Answer: Yes. Examiner will choose the best 4 answer (But not recommended because students have limited time).

Emerging Trends

Student must follow IUPAC nomenclature for all the inorganic compound, transition metal complexes and organic compound.

Reaction mechanism: Free radical substitution (alkanes), electrophilic addition (alkenes), electophilic substitution (aromatics), SN1 and SN2, polymerisation (free-radical, cationic, anionic). Students must show the movement of electrons with arrows.

Questions relate to experiment laboratory

Multistep synthesis

Answering numerical questions

  • Data / information from question
  • Significant figure / decimal point
  • Unit

Example: STPM 2008 Q6 (a)

Ammonia is a nitrogen fertiliser which is very soluble in water. It is prepared commercially by the Haber process. 1.00 mol of nitrogen gas and 1.00 mol of hydrogen gas are introduced into a 2.0 dm3 volumetric flask at 450˚C. The amount of hydrogen gas is 0.40 mol at equilibrium. Calculate the equilibrium constant for the reaction involved at this temperature. (7 marks)

Model Answer:

Information from the question: Balanced equation and must use equilibrium arrow (reversible arrow)

N2 + 3H2 <—-> 2NH3

Data from question

Balanced equation N2 + 3H2 <—-> 2NH3
Mol at equilibrium (1.00x) (1.00 – 3x) 2x

Students must use 1.00 mol (data from question) and NOT 1 mol.

Decimal point

1.00 – 3x = 0.40

x = 0.20 mol

Data from question

Balanced equation N2 + 3H2 <—-> 2NH3
Concentration at equilibrium 0.80/2.0 0.40/2.0 0.04/2.0
= 0.40 = 0.20 = 0.20

Kc = [NH3]2 / [N2] [H2]3

Kc = 12 or 13 dm6 mol-2

Concept

Students cannot use other ‘bracket’ for concentration

  • Correct: [NH3]
  • Wrong response: {NH3} or (NH3)

Significant figure

Final answer: Students need to choose the lowest significant figure from the question (data from question)

Example:  … 1.00 mol of nitrogen gas and 1.00 mol of hydrogen gas … 2.0 dm3 volumetric … hydrogen gas is 0.40 mol at equilibrium.

  • Answer: 2 significant figure

Unit

  • Correct unit: dm6 mol-2 or mol-2 dm6
  • Wrong unit: dm6 M-2 or M-2 dm6 or dm6 moles-2 or moles-2 dm6

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Berry Berry Easy wishes all STPM Chemistry candidates good luck. Please share this tips with your friends and return credits (with links) to Berry Berry Easy if you wish to share them in your blogs. :-)

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