Public Assessment of the HKDSE Chemistry Examination

1.PublicAssessmentThe public assessment of the Hong Kong Diploma of Secondary Education (HKDSE) Chemistry Exam consists of a public examination component and a school-based assessment component.

A. PublicExaminationcomponentIn Chemistry, the mark of the public examination component contributes 80% of the final subject mark.

Paper Section Question types Weighing Duration Curriculum

Paper 1Section A Multiple-choice Questions 18%

2 hours 30 minutes Compulsory PartSection B Short Questions and Structured / Essay-type Questions 42%

Paper 2 Structured Questions 20% 1 hour Elective Part (2 out of 3)

B. School-basedAssessmentcomponentIn Chemistry, students are assessed by their teachers on their performance of a wide range of skills involved in practical and non-practical related tasks throughout S.5 and S.6. The mark of the school-based assessment component contributes 20% of the final subject mark.

Year of examination Assessment types Weighing2012 and 2013 Practical related component 20%

Starting from 2014Practical related component 16%

Non-practical related component 4%

2.Standards-referencedReportingThe HKDSE makes use of standards-referenced reporting, which means candidates levels of performance will be reported with reference to a set of standards as defined by cut scores on the variable or scale for a given subject. The following diagram represents the set of standards for a given subject:

Cut scores

U 1 2 3 4 5

Variable/scale

Within the context of the HKDSE there will be five cut scores, which will be used to distinguish five levels of performance (15), with 5 being the highest. The Level 5 candidates with the best performance will have their results annotated with the symbols and the next top group with the symbol . A performance below the threshold cut score for Level 1 will be labelled as Unclassified (U).

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Exam StrategiesA. TimeAllocation

Paper1(CompulsoryPart)2hours30minutes

Section Suggested Time Allocation Approximate Time per Question

A 45 minutes 1 1.5 minutes

B 105 minutes 5 10 minutes

Allow 5 minutes for final checking.

Paper2(ElectivePart)1hour

Time Allowed Approximate Time per Question

60 minutes (answering 2 out of 3 questions) 25 30 minutes

Allow 5 minutes for final checking.

B. AnsweringSkills

Paper1A Multiple-choiceQuestions

Make your draft next to each question so that the draft can be referenced during final checking. Mark only ONE answer for each question. The statements in the options may be misleading. DO NOT spend too much time in reading the options. DO NOT leave any questions unanswered even if you do not know the answer. Eliminate the incorrect

options to choose the answer or even use wild guessing, if and only if you have no idea about the answer.

Paper1BandPaper2 ShortQuestionsandStructured/Essay-typeQuestions

Skip the questions that you do not have confidence on. Go back to those questions after you have finished the others.

The chemical equations written should be balanced. The state of the substances should also be written if possible.

In answering questions involving calculations, show your steps rather than just writing down the answers. In case you do not get the correct answer, you can get marks for the correct methods used.

Pay attention to the units in calculation, especially in the calculation of molarity and concentration. In answering questions involving drawing:

Always use a pencil. Draw exact and precise figures with tools like rulers and protractors. Choose an appropriate scale. Label significant items like the chemicals and apparatus used.

Pay attention to the question commands: Write you are supposed to write down the answer only without reasoning. Explain you should answer the question in detail.

In answering an essay-type question: The answer must be in paragraph form. State the key points of the answer clearly with specific terminology. Draw diagrams to help the explanation if necessary.

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Common Mistake Analysis1. Thechemicalequationisnotbalanced.

E.g.: Write the chemical equation for the reaction between copper and acidified potassium permanganate.

Wrong answer: Cu(s) + KMnO4(aq) + H

+(aq) Cu2+(aq) + Mn2+(aq) + K+(aq) + H2O(l)Correct answer: 5Cu(s) + 2KMnO4(aq) + 16H

+(aq) 5Cu2+(aq) + 2Mn2+(aq) + 2K+(aq) + 8H2O(l)

2. Inansweringaquestioninvolvecalculation,theunitoftheanswerisnotgiven.E.g.: 58.5 g of sodium chloride is dissolved into 1 dm3 of water. Calculate the concentration of the

solution.

Wrong answer:

Concentration of the solution =

58 523 0 35 5

1

.. .+ = 1

Correct answer:

Concentration of the solution =

58 523 0 35 5

1

.. .+ = 1 M

3. Theconceptsofthestructureandtherepeatingunitofapolymeraremixedup.E.g.: Draw the repeating unit of polyethene.

Wrong answer:

Correct answer:

4. InChemicalReactionsandEnergy,the-signismissingfortheenthalpychangeofanexothermicreaction.E.g.: When 1 mole of carbon is completely burnt in air, 393.5 kJ mol-1 of heat is evolved. Which of the

following may be the standard enthalpy change of formation of carbon dioxide?A. 393.5 kJ mol-1

B. 787.0 kJ mol-1

C. -393.5 kJ mol-1

D. -787.0 kJ mol-1

Wrong answer: ACorrect answer: C

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2012 HKDSE Exam and Mock Exam Questions DistributionPaper1(CompulsoryPart)

Paper 1A consists of Part I (24 MC questions) and Part II (12 MC questions).

Paper 1B consists of Part I (56 marks) and Part II (28 marks).

Distribution of Exam Questions:

Topics2012 HKDSE Mock 1 Mock 2 Mock 3 Mock 4 Mock 5 Revision Test

Section A Section B Section A Section B Section A Section B Section A Section B Section A Section B Section A Section B Section A Section B

I. Planet earth 2 1, 15 1

II. Microscopic world I 1, 8, 15 1 8, 16 2 5, 6, 10, 15 8 2, 9, 17 2 1, 2, 9 6 1, 3, 9, 13, 19, 23

2 8, 13, 30, 31 4, 7

III. Metals 3, 9, 16, 23 7, 9 5, 10, 13, 18, 23

3 4, 12, 18, 19 3 3, 6, 8 1 6, 8, 23, 24 3 4, 7, 8 1 10, 16, 18, 22, 23, 36

5

IV. Acids and bases 2, 4, 10, 19, 20

6 4, 9, 15, 20, 21

4, 7 3, 7, 8, 16, 22

2, 7 1, 4, 15, 16, 22, 24

4, 7, 10 10, 15, 19, 21, 22

1, 8 5, 6, 18, 24 9 4, 9, 11, 12, 19, 20

6, 9

V. Fossil fuels and carbon compounds

11, 17, 21, 24 2, 10 2, 7, 19, 22, 24

6 1, 9, 11, 17 1 10, 11, 19, 21, 23

8, 11 3, 5, 12, 16, 17

7, 10 14, 15, 20, 22

4, 6, 8 2, 7, 26, 34 2, 10, 12

VI. Microscopic world II 5, 12 4 11 1 20 5 7 3 11 2 2 5 5, 35 3

VII. Redox reaction, chemical cells and electrolysis

6, 13, 18, 22 3, 5 1, 3, 12, 17 5, 8 13, 14, 21, 24

4, 9 5, 12, 14, 20 6, 9 4, 7, 18, 20 5 11, 12, 17, 21

7 3, 17, 21, 25, 28, 33

8, 11

VIII. Chemical reactions and energy

7, 14 8 6, 14 9 23 6 13, 18 5 13, 14 4, 9 10, 16 3, 10 6, 14 13

IX. Rate of reaction 25 11 26, 33, 35 10 26, 31 14 28 12 29, 32 12 26, 33, 34 12 24, 27 14

X. Chemical equilibrium 26, 27, 35 13 29, 31 15 28, 30, 32 10 25, 26, 29, 35

17 31, 33, 36 13 29, 35 14 29, 32 15

XI. Chemistry of carbon compounds

28, 29, 32, 33, 34, 36

12, 14, 15 25, 28, 30, 32, 34, 36

12, 13, 14 25, 27, 29, 33, 34, 35

11, 12, 13 27, 30, 31, 32, 34, 36

13, 14 25, 26, 28, 30, 34, 35

11, 14, 15 25, 27, 28, 30, 31, 36

11, 15, 16

XII. Patterns in the chemical world

30, 31 16 27 11 36 15 33 15, 16 27 16 32 13

About 70% of the questions are set at the former HKCE Examination level. The rest (30% of the questions) are

set at the former HKAL Examination level.

Paper2(ElectivePart)

Paper 2 consists of three questions (20 marks each). Candidates should answer two questions.

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Useful FormulaeMicroscopicWorld:Atomic number = Number of protonsMass number = Number of protons + Number of neutrons

Relative atomic mass = Average relative isotopic mass of the element12

Mass of an atom of carbon-12

Moleandconcentration:

Number of moles = Mass of the substance in g

Molar mass in g mol-1 =

Number of particlesAvogadros number

Percentage by mass of an element in a compound

= Atomic number of an element Number of an element in the compound

Formula mass of the compound 100%

Concentration (g dm-3) = Mass of solute in g

Volume of solution in dm3

Concentration (M or mol dm-3) = Number of moles of solute

Volume of solution in ddm3

Rateofreaction:

Rate of reaction = D[reactant]

Dt or

D[product]Dt

Under the same temperature and pressure, Number of moles of gas = Volume of gas

Molar volume of gas

ChemicalEquilibrium:

For a reversible reaction aA + bB cC + dD, Kc = [C] [D]

[A] [B]

eqmc

eqmd

eqma

eqmb

.

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135 2012 Hong Kong Educational Publishing Co.

4.

Which of the following combinations would produce the largest current flowing from metal P to metal Q in the external circuit?

Metal P Metal Q

A Mg Ag

B. Ag Na

C. Ag Zn

D. Zn Cu

5. Which of the following statements concerning propene is/are correct?

(1) It can be oxidized by K2Cr2O7/H+ solution.

(2) It can undergo addition polymerization.(3) It can be prepared by the catalytic cracking of a saturated hydrocarbon.

A. (1) only

B. (3) only

C. (2) and (3) only

D. (1), (2) and (3)

6. The experiment is carried out to find the order of m