chemistry and combined science (chemistry part) briefing session

HHoonngg KKoonngg DDiipplloommaa ooff SSeeccoonnddaarryy EEdduuccaattiioonn

CChheemmiissttrryy && CCoommbbiinneedd SScciieennccee ((CChheemmiissttrryy ppaarrtt))

DDeecceemmbbeerr 22000088

Programme

Registration

Introduction

Contents

T M Li

Speakers Duration (min.)

20

10

Sample Papers Structure T M Li 20

Sample Questions for Electives W H Fong 15

SRR Exemplars

BREAK

SRR Level Descriptors

K C Pun

T M Li

15

20

10

SBA Requirements T M Li 25

Q & A ALL 45

2

3

Papers Sections Parts Topics

examined Questions Questions Sections Papers

Paper 1 (2.5

hours)

Section A

(18%)

Part I Topics 1-8 24 M.C.

24 M.C. Section A (12%)

One paper only (100 mins)

Part II Topics 1-12* 12 M.C.

Section B

(42%)

Part I Topics 1-8

structured questions

(47 marks) essay (9 marks)


(47 marks) essay (9 marks)

Section B (28%)

Part II Topics 1-12* structured questions

(28 marks)

Paper 2 (1 hour)

20% Topics 13-15#


20 marks per elective (40 marks)

SBA 20% 10% SBA

Total 100% 50% Total

Chemistry Combined Science (Chemistry Part)

NSS Chemistry Public AssessmentNSS Chemistry Public Assessment

* Emphasis would be put on Topics 912

# May include contents of Topics 112

CChheemmiissttrryy

Papers Sections Parts Topics

examined Questions

Section A Part I Topics 1-8 24 M.C.

Paper 1 (18%) Part II Topics 1-12* 12 M.C.

(2.5 hours)

Section B Part I Topics 1-8

structured questions (47 marks)

essay (9 marks)(42%)

Part II Topics 1-12* structured questions

(28 marks)

Paper 2 (1 hour)

20% Topics 13-15# structured questions

20 marks per elective (40 marks)

SBA 20%

Total 100%

* Emphasis would be put on Topics 912

# May include contents of Topics 112 4

CCoommbbiinneedd SScciieennccee ((CChheemmiissttrryy PPaarrtt))

Papers Sections Questions

One paper only (100 mins)

Section A (12%) 24 M.C.

Section B (28%)

structured questions (47 marks)

essay (9 marks)

SBA 10%

Total 50%

5

6

Sample Papers Structure

Multiple Choice

1. All MC items appear in Comb Sci (Chem) also appear in Chemistry 2. 23 MC items of Comb Sci (Chem) come from Part I of Chemistry, and

1 MC item of Comb Sci (Chem) comes from Part II of Chemistry (i.e. Q.19 of Comb Sci (Chem) = Q.27 of Chemistry)

Conventional Question

1. 52 out of 56 marks of Comb Sci (Chem) come from Chemistry 2. Only 4 marks (Q.5) in Comb Sci (Chem) do not come from Chemistry 3. The same paragraph-length/ essay question is asked in

Comb Sci (Chem) and Chemistry

Questions for the Combined Science (Chemistry part) will be, as far as possible,

extracted from those of the Chemistry

Chemistry-Paper 2 (Electives)

One question is set for each of the three electives, candidates are required to answer any 2 out of them.

7

Industrial Chemistry

1(c) The reaction for the production of methylpropene from 2-bromo-2-methylpropane is represented by the following equation :

CH3 CH3

H3C C CH3 + C2H5ONa → H3C C CH2 + C2H5OH + NaBr

Br

(i) With reference to green ceconomy of the reaction.

hemistry, calculate the atom

Answer: Atom economy

= molar mass of desirable product / sum of molar masses of all products = molar mass of methylpropene /(MM of methylpropene+ethanol+sodium bromide) = 56/(56+46+102.9) x 100% = 27.3% (2 marks)

8

9

Industrial Chemistry

(ii) Apart from atom economy, suggest TWO other factors that scientists should consider in order to conduct a green production process.

Answer:

Examples of other factors (Any TWO):

Waste Minimisation at Source

Use of Catalysts in place of Reagents

Use of Non-Toxic Reagents

Use of Renewable Resources

Use of Solvent Free or Recyclable Environmentally Benign Solvent systems (2 marks)

10

2(a) The structure of compound A , which exhibits liquid-crystalline behaviour, is shown below :

O

O

(i) Compound A can be formed by condensation of benzoic acid with cholesterol. Draw the structure of cholesterol.

Materials Chemistry

OH

Answer:

(2 marks)

Materials Chemistry

(ii) What is the difference between ‘true liquid’ and ‘liquid crystal’ ?

Answer: Molecules in ‘true liquid’ have no intrinsic order.

Molecules in liquid crystal possess some degree of translational freedom with certain orientation preference in one or two direction(s).

(2 marks)

(iii) Describe briefly the arrangement of the molecules in cholesteric phase liquid crystals.

Answer: The molecules line up in positions that they are slightly twisted from the molecules next to them giving rise to a helical-like arrangement.

(2 marks)

11

Materials Chemistry

(iv) Outline the working principle of cholesteric phase liquid crystals in Liquid Crystal Display (LCD).

Answer: In LCD, liquid crystals are packed between a polariser and an analyser.

When light passes through the polarizer, it will be polarised in the direction allowed by the polariser.

The polarised light will be guided by the molecules in each layer of the liquid crystals.

The polarised light is rotated by the desired angle and hence can pass through the analyser to give rise to bright region on the LCD.

(4 marks)

12

100

50

Analytical Chemistry 3(a) Compound G , with relative molecular mass of 58, has the following

composition by mass : C : 62.1% H : 10.3% O : 27.6% The infrared and mass spectra of compound G are given below.

100

80

4000 3000 2000 1500 1000 500 Wavenumber / cm–1

10 20 30 40 50 60 70

Rel

ativ

e In

tens

ity

60

40

20

00

Characteristic Infra-red Absorption Wavenumber Ranges (Stretching modes)

Bond Compound type Wavenumber range /cm–1

C=C Alkenes 1610 to 1680

C=O Aldehydes, ketones, carboxylic acids and derivatives 1680 to 1800

C≡C Alkynes 2070 to 2250

C≡N Nitriles 2200 to 2280

O–H Acids (hydrogen-bonded) 2500 to 3300

C–H Alkanes, alkenes, arenes 2840 to 3095

O–H Alcohols, phenols (hydrogen-bonded) 3230 to 3670

N–H Amines 3350 to 3500 13

Analytical Chemistry

(i) Deduce the molecular formula of compound G .

Answer: number of carbon atoms = 0.621(58)/12 = 3 number of H atoms = 0.103 (58)/1 = 6 number of O atoms = 0.276 (58) / 16 = 1 Molecular formula of G is C3H6O. (2 marks)

(ii) From the given spectral information and the molecular formula obtained in (i), deduce the structural formula of compound G.

Answer: From the IR spectrum, the presence of a sharp absorption peak at 1740 cm–1 indicates the presence of a carbonyl group.

From the mass spectrum, the peaks at m/e 29 corresponds to C2H5+ and

the peak at m/e 58 corresponds to CH3CH2CHO+.

The structural formula of G should be CH3CH2CHO. (4 marks) 14

Analytical Chemistry

(iii) Suggest an experiment, with detailed procedures, to support the structure of compound G you have deduced in (ii).

Answer: Add 2,4-dinitrophenylhydrazine to G to prepare the corresponding 2,4-dinitrophenylhydrazone.

Recrystallize the 2,4-dinitrophenylhydrazone.

Measure its melting point using a melting point apparatus.

A sharp melting point which is the same as that quoted in the literature will support the deduction of G.

(4 marks)

15

SSttaannddaarrddss RReeffeerreenncceedd RReeppoorrttiinngg ((SSRRRR))

� The standards are held constant � The percentage of students awarded a

given level may vary from year to year � The standards are more informative � Level descriptors together with exemplars

can better reflect the standards

16

SSttaannddaardrdss sseettttiinngg • Based on examination results, candidates are awarded

with a total score • To determine the minimum scores (also known as cut

scores) a candidate must obtain for meeting various standards (Levels 1-5)

17

18

Level DescriptorsLevel Descriptors The typical performance of candidates atThe typical performance of candidates at LevelLevel 55 :

DRAFT

� demonstrate comprehensive knowledge and understanding of facts, concepts and principles in chemistry

� apply the concepts of chemistry to a wide range of unfamiliar situations

� analyse, synthesise and critically evaluate information from multiple perspectives and in an in-depth manner

� effectively and consistently communicate ideas in a succinct, logical and coherent manner with accurate use of scientific terminology and appropriate formats

� design and conduct scientific investigations, evaluate procedures, handle and analyse data collected, and draw valid conclusions

19


DRAFT

� demonstrate sound knowledge and understanding of facts, concepts and principles in chemistry

� apply the concepts of chemistry to unfamiliar situations

� analyse, synthesise and evaluate information from several perspectives

� communicate ideas in a logical and coherent manner using scientific terminology and appropriate formats

� design and conduct scientific investigations, handle and interpret data collected, and draw conclusions

20


DRAFT

� demonstrate adequate knowledge and understanding of facts, concepts and principles in chemistry

� apply the concepts of chemistry to unfamiliar situations with guidance

� construct relationships and analyse information

� communicate ideas in a clear, structured manner using scientific terminology and appropriate formats

� design and conduct scientific investigations, handle and interpret data collected, and draw conclusions with guidance

21


DRAFT

� demonstrate basic knowledge and understanding of facts, concepts and principles in chemistry

� apply the concepts of chemistry to familiar situations

� describe relationships and handle information

� communicate ideas using appropriate scientific terms

� conduct practical work by following instructions, handle and interpret data collected, and draw simple conclusions

22


DRAFT

� recall elementary facts and principles in chemistry

� apply the concepts of chemistry to simple and familiar situations

� handle simple information presented in a straightforward manner

� communicate straightforward ideas using scientific terms

� conduct simple practical work by following instructions and collect the required data

TThhee 55 LLeevveellss ooff SSRRRR

• A panel of judges (experienced teachers, markers, examiners and university colleagues, etc.) determines the boundaries between levels with reference to 1. Level descriptors 2. Previous CE & AL results

• Annotated exemplars were selected to illustrate typical performance at each level.

23

24

Level 5 Exemplar DRAFT

9.

25


Comments:

• Showing extensive knowledge and clear understanding on qualitative analysis by the use of appropriate reagents with accurate observations

• Showing excellent ability in logical and accurate presentation of chemical tests in a systematic way • Demonstrating effective communication skills using correct scientific terminologies such as flame

test and precipitate

26


27


Comments:

• Showing sound knowledge and clear understanding on drawing three-dimensional diagrams for diamond, and caesium chloride

• Showing ability in accurate explaining the electrical conduction of substances in terms of the availability of mobile ions and delocalized electrons

• Demonstrating effective communication skills such as using labeled diagrams

28


29


Comments:

• Showing adequate knowledge and understanding on three-dimensional structures of diamond and graphite • Communicating ideas with clear written expression on concepts related to electrical conductivity using

correct terminology such as ‘delocalization of electrons’ and ‘ions are not mobile’ • Showing some errors in using chemical terms such as ‘ionized electrons’ and was unable to draw three-

dimensional diagram in a careful manner

30


Comments:

• Showing basic knowledge on simple chemical reactions and the related observable changes such as the evolution of gas and the formation of precipitate

• Expressing simple chemical reactions by correct use of chemical formulae as exemplified by the reaction between zinc and dilute hydrochloric acid

• Showing some errors in balancing simple chemical equation as exemplified by the reaction between sodium hydroxide solution and iron(II) sulphate solution

31


Comments:

• Showing elementary knowledge and understanding on reaction between metal and dilute acid by giving an accurate observation

• Showing errors in balancing chemical equations

32

BREAK

33

SBA

NNSSSS CChheemmiissttrryy SScchhooooll--bbaasseedd AAsssseessssmmeenntt

SBA TASKS

Weighting 20% of Public Assessment

Mode Practical Related Non-practical

Related

Task type

Basic Chemical Analysis

Experiment Investigative

Study Assignment

Task code

BCA EXPT IS ASSN

34

SSBBAA rreeqquuiirreemmeennttss

Number of assessments on SBA tasks

BCA EXPT IS ASSN

S6

≥1 ≥3 1 ≥1 S5

S4

35

SSBBAA rreeqquuiirreemmeennttss

Number of Experiments (including BCA & EXPT, but excluding IS)

S6

≥8 S5

36

NNSSSS CCoommbbiinneedd SScciieennccee ((CChheemmiissttrryy PPaarrtt)) SScchhooooll ––bbaasseedd AAsssseessssmmeenntt

SBA REQUIREMENTS Number of assessments on SBA tasks

Number of Experiments (including VA & EXPT)VA EXPT ASSN

S6 ≥1 ≥2 ≥1 ≥4

S5

37

Year of

examination Implementation of SBA

2012 and 2013

Schools are required to submit SBA marks for the practical related component only. The mark of this component will contribute to 20% of the final subject mark of CHEMISTRY and 10% of the final subject mark of COMBINEDSCIENCE respectively.

Note: In order to further alleviate the workload, marks of ‘Investigative Study’ of CHEMISTRY are NOT required in this stage.

2014 and thereafter

Schools have to submit SBA marks for both the practical and non-practical related components. The marks of both components will contribute to 20% of the final subject mark of CHEMISTRY and 10% of the final subject mark of COMBINED SCIENCE respectively.

38

Minimum number of assessments required for CHEMISTRY

Practical related task Non-practical related task

Basic Chemical Analysis (BCA)

Experiment

(EXPT)

Investigative Study

(IS)

Assignment

(ASSN)

2012 & 2013 exam

S5 1(8%) 1(4%) -- --

S6 -- 2(8%) -- --

2014 exam and thereafter

S5 1(4%) 2(4%) -- 1(4%)

S6 -- 1(2%) 1(6%) --

39

Minimum number of assessments required for COMBINED SCIENCE(CHEMISTRY part)

Practical related task Non-practical related task

Volumetric Analysis (VA)

Experiment (EXPT)

Assignment (ASSN)

2012 & 2013 exam

S5 1(4%) 1(3%) --

S6 -- 1(3%) --

2014 exam and thereafter

S5 1(3%) 1(2%) --

S6 -- 1(2%) 1(3%)

40

41

Teachers will be asked to submit a list of tasks done in S5 to S6, showing the coverage of the different types of work.

School repeaters / transfer candidates have to meet the respective minimum requirements for SBA in S6 as follows:

Year of examination

Minimum number of assessments required for CHEMISTRY

2013 2 EXPT (20%)

2014 and thereafter

1 EXPT (5%) and 1 IS (15%)

Year of examination

Minimum number of assessments required for COMBINED SCIENCE(CHEMISTRY part)

2013 1 EXPT (10%)

2014 and thereafter

1 EXPT (5%) and 1 ASSN (5%)

42

Switching of courses

Students who follow a science course with a Chemistry component (including Chemistry, Combined Science (Chemistry part) and Integrated Science) at S5 are allowed to switch to another one with a Chemistry component in their S6 year of study, provided that the school concerned is permitted to present candidates for the examination of the subject to be entered by the candidates. Such switching of courses is also allowed for school repeaters.

They are required to fulfill the same SBA requirements as those for school repeaters and transfer candidates

(i.e. S6 requirement)

43

Private Candidates

Private candidates will NOT need to complete the SBA component. Their subject mark will be based entirely on their public examination results and adjusted accordingly.

Private candidates who have SBA marks obtained in previous examinations are NOT allowed to carry these marks to the current examination.

44

HHooww ccaann sscchhoooollss ppllaann ffoorr SSBBAA IImmpplleemmeennttaattiioonn

� Conduct SBA as an integral part of teaching and learning and not treat it as an “add-on”

� Set up school’s own assessment plan, specify the no of assessment activities to be conducted for individual subjects

� Coordinate the conduct of the SBA across subjects so that students’ work will not be concentrated into one or two critical months

� Incorporate SBA as a part of schools’ internal assessment program and replace some of the current assessment activities, e.g. assignments, tests etc

45

PPrrooppoosseedd SSBBAA MMaarrkk SSuubbmmiissssiioonn CCoooorrddiinnaattiioonn aaccrroossss ssuubbjjeeccttss iinn 22001122 HHKKDDSSEE aanndd HHKKAALLEE ((DDrraafftt aass ooff OOcctt 0088))

1. 2011 (S5 for HKDSE and S6 for HKALE)

HKDSE HKALE

Mid May Early June Mid June Late June Early July Mid July Late June Early July

LS – Stage 1 DAT

ICT

Biology

Chemistry

Chi Lang

Integrated Science

History

Visual Arts

Chi History

Eng Lang

Chemistry Chinese Lang &

Culture

Physics

Combined Science

Chi Lit

2. 2012 (S6 for HKDSE and S7 for HKALE)

HKDSE HKALE

Mid Oct Mid Jan Early Feb Mid Feb Late Feb Early Mar Late Mar Early Mar Mid Mar Late Mar

LS – Stage 2 LS – Stage 3 History Physics ICT Chi Lang Eng Lang LS Physics Visual Arts

DAT

Visual Arts

Chemistry

Biology

Chi History

Integrated

Electronics

Computer

Chemistry

Biology

Chi Lang &

Culture

Combined

Science

Science Applications

Computer

GPA Chi Lit

Studies

46

PPrrooppoosseedd SSBBAA MMaarrkk SSuubbmmiissssiioonn CCoooorrddiinnaattiioonn aaccrroossss ssuubbjjeeccttss iinn 22001122 HHKKDDSSEE aanndd HHKKAALLEE ((DDrraafftt aass ooff OOcctt 0088))

2011

HKDSE HKALE

Mid June Chem (S5), Comb Sci (S5)

Late June Chem (S6)

HKDSE HKALE

2012 Mid February Chem (S6), Comb Sci (S6)

Mid March Chem (S7)

47

CCoommiinngg NNSSSS ddooccuummeennttss ((TTeennttaattiivvee))

1. SRR booklets with sample papers

Jun 09

2. SBA handbook Jun 09

3. SBA sample tasks and assessment criteria

Jun – Sep 09

48

chemistry and combined science (chemistry part) briefing session

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