Perkongsian Amalan Teknik Menjawab Soalan Chemistry Paper 3 SPM (4541 / 3)

Format of Paper 4541 / 3Time; 1hr 30 minutes Marks; 50 marks

(i) Construct Tested;

Science Process Skills (16 aspects)Task; answer all 2 or 3 questions in 1hr 30 minLevel of Difficulty L : M : H = 5:3:2

(1) Structured questions (45 minutes)

Making observation, inferencing, identifying and controlling the variables, hypothesising, classifying, making operational definition, reading instruments / measurements, constructing table, plotting graph, predicting, interpreting data.

(2) Extended Response Item (45 minutes)

Stating aim / problem statement (always a question !), hypothesis, listing the variables, materials & apparatus, writing the procedure, tabulation of data.(A diagram usually helps in this question though there is no specific allocation of marks for diagram, because certain steps left out in the procedure write-up may be able to be inferred from the diagram))

(ii) Scoring for item :

3 marks Excellent : The best response 2 marks Satisfactory : An average response 1 mark Weak : An inaccurate response 0 mark No response or Wrong response

(B) Guide on Answering

(i) Answering the Structured Questions:Quite similar to the structured questions in Section A of Chemistry Paper 2, but emphasises on the process skills:

Recall the topic / sub-topic and application of the concepts and theories related to the question;

(ii) Answering the Extended Response Item (Designing / Planning of experiment)

No need to give complete report ( as the PEKA report) as this is only the planning stage.Procedure is preferably written in the active form (although the passive form is also accepted)

Normally the question requires :

Problem Statement / AimAll the variablesHypothesisList of materials and apparatusProcedureTabulation of data

(C) GUIDE TO MARKING PAPER 4541/3 :

Bilingual answer / Mixed language is accepted. ( BM or BI only )Grammatical errors are ignored.Avoid use of American spelling system. (e.g. color, oxidize)Wrong spelling often ignored unless for technical terms e.g. alkane, covalent bonding, chlorine atom.Avoid using abbreviation. List of substances and apparatus.

7. Case when more than one answer is given. e.g. a student gives 2 answers for hypothesis, then the score awarded depends on the accuracy of both answers

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8. Making observation In Paper 3, observation is drawn from sight only ! (NOT from all 5 senses like in Paper 2 !!) e.g. reject beaker feels warm accept temperature rises 9. Graph sketching / plottingShould show axes with arrowhead with correct labels, correct units & correct shape (curve or line)10. Diagrams for the set-up of apparatus not required but encouraged

11. Constructing a table :title of heading be based on the terms used in question : (e.g. question use Initial temperature , students cannot change it to starting / beginning temp )12. Stating volume of a liquid and mass of a solid the use of the words amount and quantity is rejected. (e.g. Constant Variable : amount of HCL is the same wrong ! Must say the volume & concentration of HCL is the same. Rate of reaction is the same because the quantity of reactants used is the same REJECT !! )

13. Accuracy in taking measurementsDegree of accuracy depends on the type and calibration of instrument usedAble to give accuracy to at least one decimal place is expected for score 3;

14. CalculationsFormula should use commonly used symbols, e.g. : H = mcCorrect units must be statedSteps must be shown clearly

(D) Some Terms Markers Use

wrong cancel right (wcr)benefit of doubt (bod)error carried forward (ecf)avoid double penalty (adp)Reject (r) and Accept (a)

(E) Popular topics in Paper 3 :

questions are based on activities and experiment;

Applications of theories and concepts rather than memorisation;

Determination of empirical formula of metal oxide. (Q1 2004)Change of state of matter : e.g. boiling point / freezing point of naphthalene (Q1 2005)(a) Construction of reactivity series of metals towards oxygen(b) Reaction of Group 1 and Group 17 of PTE. (Q2 2004,2008)

Electrochemistry (a) Construction of ECS : Q2 2005

(b) Chemical cell / Factor affecting voltage: Q2 2007

(c) Electrolysis cell / Application of electrolysis ( extraction of reactive metals, electroplating & purification of metal factors ) and factors affecting selective discharge of ions.

Comparing physical or chemical properties of :

(i) an alloy-pure metal, (Q3 2003, Q3a 2005)(ii) vulcanized rubber natural rubber, (Q2 2006)(iii) hydrocarbons relating RMM and physical properties.

Acids & Bases And Salts

(a) role of water in showing acidity & alkalinity

(b) titration

(c) qualitative analysis of cations & anions

Preparation of

(a) soluble salts of potassium, sodium and ammonium.(b) other soluble salts.(c) insoluble salts.(d) continuous variation method (Q2 2003)

Rates of reactions determination from graph and calculation

Effect of concentration: (Q3b 2005)Effect of temperature; (Q1 2003)Effect of total surface area:Effect of catalyst:

Preparation & properties of esters (esterification). (Q3 2004)

Redox rusting : Q3a 2003Effect of another metal an rustingConversion of iron(II) and iron(III) ions, redox cell

(a) Thermochemistry : Q1 2007

(b) Heats of reaction :(i) precipitation(ii) displacement(iii) neutralisation Q1 2006(iv) combustion

12. (a) Preparation of soap12.(b) Comparing effectiveness of different detergents

Paper 3All questions are based on what the students have studied in the syllabus

Decimal place Burette 2 decimal places 25.00 cm3 / 0.00 cm3Thermometer / stopwatch one decimal place 25.0 oC / 3.5 s

Variables :State only one variable for controlled / fixed variableIf state more than one variables, one of the answers is wrong, then the wrong will cancel the right (wcr effect !)

Skills that will be evaluated in Paper 3 (Structure)ObservationClassifyingMeasuring and Using NumbersMaking inferenceCommunicatingUsing Space and Time RelationshipInterpreting DataDefining OperationallyControlling VariablesMaking hypothesisPredicting

Plan / Design an experimentProblem statement (always a ? Statement)Hypothesis (can be a positive or negative hypothesis)Identifying and controlling variables. Suitable apparatus and materialProceduresResult (Tabulating data) Dont fill in any data because u are planning an experiment