This post is relevant to students taking the GCE O-Level Pure Chemistry (syllabus code: 6092) examination currently.
Paper 2 Written Paper this year is considered quite do-able by most students. Even though it is not the most difficult written paper we have seen in the last 10 years, there are still couple of “weird” questions which some students will find it hard to apply to.
In fact, i am hearing more students telling me that they are not very confident of doing well for Paper 2 Written Exam. Many commented that this year’s questions are unusual as compared to the last 10 years when they compared it to questions found in the Pure Chemistry Ten Years Series books. They found that many of the major topics/concepts which are usually tested in Paper 2 did not appear this year! They also complained that the space/lines given for them to write the answers for quite a number question in the exam script is insufficient also.
At Winners Education, we are quite “lucky” this year. Many of the fundamental questions and application questions that were discussed in our Sec 4 Saturday and Sunday weekly tuition classes as well as my Sec 4 Friday Revision Class came out. I hope our students revised those concepts and questions which we have discussed previously and performed well for this Paper 2.
Post Mortem (Topical Analysis) of Paper 2 Written Paper:
Here is the list of topics and concepts that are being tested in the recent Pure Chemistry Paper 2 Written Paper:
Question A1 is on Organic Chemistry – Macromolecules. [I mentioned to our students that one of these years, Cambridge Examiners are going to go heavy on Macromolecules because they know students are quite weak in this topic]
Question A2 is on Atomic Structure – Isotopes as well as on Chemical Bonding – Physical Properties of Substances. [glad we emphasised on the importance of the definition of Isotopes during the revision phase]
Question A3 is on Solubility of Salts as well as on Qualitative Analysis (QA) – Test for Cations using aqueous ammonia and sodium hydroxide solution & test for nitrate anion. [Also told my students that QA was not really being tested in Paper 3 Practical Exam, so it should come out in Paper 2 Written Exam and Paper 1 MCQ].
Question A4 is on Kinetic Particle Theory – Diffusion of Gases which depends on molecular mass of gases as well as the surrounding temperature. [glad we covered this basic topic during revision phase and not skipped it like most tuition centres as well as schools]
Question A5 is on Acids & Bases – specifically on Types of Oxides and how their solutions affect the litmus paper (indicator). Students are also tested on Chemical Bonding – Dot-and-cross diagram for Na2O (an ionic compound) as well as on Mole Calculations – to calculate the Theoretical yield and then % Yield. [Types of Oxides as well as Indicators are important concepts which we emphasised greatly during the revision phase].
Question A6 is on the application of Metals & Reactivity Series – Sacrificial Protection and Barrier Protection of steel underground pipes. [this is an important concept and we covered at great length on its application].
Question A7 is on Electrolysis – How the use of different metal electrodes in Simple Cells produces different voltages. [glad we covered both Electrolytic Cells as well as Simple Cells. It comes to a shock to many students in Singapore that Electrolytic Cells did not come out at all. Nobody expected Cambridge Examiner to test on the “less discussed” Simple Cells].
Question B8 is a Data Source Question on Bleach. Students are tested on several concepts:
- Chemical Bonding on Dot-And-Cross Diagram
- Redox Reactions on Oxidation States [i repeated the concepts and application of Oxidation States at least twice during revision phase]
- Mole Calculations – Calculate and show how the % by mass of chlorate (I) ion in calcium chlorate (I) is higher than sodium chlorate (I)
- Solve questions by sourcing from the data / info given
Question B9 is on Rate of Reaction – Effect of Catalyst
- First part of the question is actually based on the concept on Heterogenous Catalyst in GCE A-Level H2 Chemistry. Considered a fair question still, since diagram is given which clearly show what happens during the catalytic process. Students just need to follow each stage of the diagram closely and describe what they see. [as expected, Cambridge Examiners want students to follow the question and apply].
- Students are then asked to complete and label two energy profile diagrams, one with and one without the catalyst. So this is another basic question which student should score well.
- As usual, students are finally asked on how catalyst increases the rate of reaction based on Collision Theory.
Question B10 Either is on Organic Chemistry
- This question is about the oxidation of ethanol to ethanal (not in GCE O-Level Pure Chemistry syllabus) to ethanoic acid.
- It starts by asking students to name two substances that can oxidise ethanol to ethanoic acid. The two substances are obviously oxidising agents.
- It then asks to name and give the formula for the third member of the alcohol and carboxylic acid homologous series.
- The structural formula of ethanal is given in the question and ethanal is stated as the second member of the aldehydes homologous series (not in GCE O-Level Pure Chemistry syllabus once again). Students are then asked to draw out the structural formula of the first member of the aldehydes homologous series.
- Next part of the question gave 3 equations and students are asked to write out the overall equation. They are also being asked to identify the catalyst in the multiple step reactions [which I have discussed with our students and have told them it is very common when it comes to GCE A-Level H2 Chemistry Exam and the Cambridge Examiners may just test them in GCE O-Level Pure Chemistry Exam anytime].
Question B10 OR is also on Organic Chemistry
- Question starts by giving three isomers (two carboxylic acids and one ester).
- Students are first being asked to describe and explain the effect on the Universal Indicator on each of the isomers.
- Students are then asked to determine the carboxylic acid and alcohol which will give the ester isomer.
- Students are then finally being asked to determine the empirical formula and molecular formula of another isomer (Mole Calculation).
- [glad we covered extensively on Organic Chemistry during the revision phase].
So that is Paper 2 SQ which has a weightage of 50%. I will not be sharing the suggested answers over here since I don’t want to create any panic for students currently taking the examination now (in case you didn’t get the correct answer). I will be sharing my suggested answers in 2020 edition of GCE O-Level Pure Chemistry Ten Years Series books by SAP Publishers. The books should hit Popular Bookstores and school book shops in February 2020 and will serve as a very good reference guide for students taking GCE O-Level Exam in 2020.
Note that this is not the final exam for Pure Chemistry. There is still the last paper which will determine the final grade of your Pure Chemistry.
Fast forward, students will finish up their GCE O-Level Examination with their last paper – Pure Chemistry Paper 1 MCQ which has a weightage of 30%.
Students must really treasure this paper. Doing well in it will definitely pull up their overall Pure Chemistry grade.
In view that this is the last paper of the whole GCE O-Level Examination, many students would have gotten complacent. This is the best time for you to catch up, simply by revising well and aim to score full marks (40/40)for it! It is possible. Every year, our students report back to say that they manage to Score 100% for O-Level Pure Chemistry Paper 1 MCQ. This is as good as saying they have secured 30%!
Now, let’s take a look at what are the possible topics or concepts which might be tested for Paper 1 MCQ on 15th November 2019.
Usually, the same concepts will not be tested twice in the same year. So, for those concepts already tested in Paper 2 Written Paper, we most likely won’t see them again in Paper 1 MCQ. This also means, those topics/concepts not tested in Paper 2 Written Paper will have a very high chance to be tested in Paper 1 MCQ.
Following are the topics/concepts which may come out in Paper 1 MCQ:
1. Kinetic Particle Theory
- Changes of states of matter
2. Measurement and Experimental Techniques
- Appropriate apparatus for measuring mass, time, temperature and volume of liquids and gases
- Selecting appropriate apparatus for collecting a sample of gas (displacement of water, downward delivery, upward delivery techniques).
- Drying of gas using concentrated sulfuric acid, quicklime (calcium oxide) and fused calcium chloride.
3. Separation and Purification Techniques
- Methods of separating and purifying mixtures of different states of matter using techniques such as filtration, evaporation to dryness, crystallisation, magnetic separation, sublimation, simple distillation, fractional distillation, use of separating funnel as well as chromatography.
- Methods of determining the purity of substances such as melting point, boiling point and chromatography.
4. Elements, Compounds and Mixtures
Identifying whether a substance is an element, compound or mixture
Differences between compounds and mixtures
5. Atomic Structure
- Electrons, protons and nucleus in an atom
- Atomic number (proton number) and atomic mass (nucleon number)
- Similarity and difference in isotopes
6. Chemical Bondings
- Differences in the ionic bonding, chemical bonding and metallic bonding
- Structure and physical properties of ionic substances, covalent substances and metallic substances
- Differences in the physical and chemical properties of simple molecular structures versus giant molecular structures
- Differences in the physical and chemical properties of diamond versus graphite
7. Writing Equations
- Determine the balanced chemical equation or ionic equation for a specific chemical reaction
8. Mole Concept and Chemical Calculations (also known as Mole Calculations)
- Relative atomic mass, relative molecular mass and relative formula mass
- Mole and molar mass
- Empirical and molecular formulae
- Percentage composition of compounds
- Molar volume of gases
- Avogadro’s Constant
- Concentration of solutions
- Molar ratio comparison using a balanced chemical equation
- Limiting and excess reactants
- Volumetric analysis
- Percentage yield and percentage purity
9. Acids and Bases
- Physical and chemical properties of acids
- Physical and chemical properties of alkalis
- Strength of acids and alkalis
- Basicity of acids
- Role of water in acidity
- Strength versus concentration
- The pH Scale
- Indicators such as litmus and universal indicators
- How to control the acidity of soil by using quicklime and slaked lime
- Types of oxides (acidic, basic, neutral and amphoteric oxides) and their properties
- Solubility of salts
- Water of crystallisation
- Anhydrous and hydrated salts
- Methods of preparation of salts (titration, acid with excess substances, ionic precipitation)
11. Qualitative Analysis (QA)
- Tests to identify aqueous cations
- Tests to identify anions
- Tests to identify gases
12. Redox Reaction (Oxidation and Reduction)
- Oxidation / reduction in terms of gain / lose of oxygen atoms
- Oxidation / reduction in terms of gain / loss of hydrogen atoms
- Oxidation / reduction in terms of gain / loss of electrons
- Oxidation / reduction in terms of increase / decrease of oxidation states (numbers)
- Test of oxidising agents using acidified potassium manganate (VII)
- Test of reducing agents using aqueous potassium iodide
13. Metals and Reactivity Series
- Properties of pure metals versus alloys
- Determining the order of reactivity of metals using The Reactivity Series
- Reaction of metals with H2O
- Reaction of metals with dilute acid solutions
- Metal displacement reactions
- Reduction of metal oxides with hydrogen / carbon
- Thermal decomposition of Metal Carbonates
- Methods of extraction of metals
- Blast Furnace – extraction of iron from haematite
- Properties and used of the 3 types of steels (mild steel, high carbon steel and stainless steel)
- Conditions for rusting to occur
- Rust prevention using barrier method or sacrificial method
- Advantages and disadvantages of recycling metals
- Electrolytic cells using aqueous or molten electrolytes and use of inert or reactive electrodes
- Purification of copper
- Simple cells
15. The Periodic Table
- Elements are arranged in the order of atomic number (number of protons)
- Group versus period
- Metals versus non-metals
- Properties of Group I elements (Alkali Metals) and their trends down the group
- Properties of Group VII elements (Halogens) and their trends down the group
- Properties of transition metals
- Properties of Group 0 elements (Noble Gases)
16. Energy Changes
- Exothermic Changes versus Endothermic changes
- Energy level diagram
- Energy profile diagram and activation energy
- Bond-breaking and bond-making
- Combustion of fuels
- Hydrogen-oxygen fuel cell
- Advantages and disadvantages of using hydrogen as a fuel
17. Speed of Reaction (also known as Rate of Reaction)
- Factors affecting the speed of reaction (temperature, concentration of solutions, pressure of gases, surface area of solids and the use of catalysts)
- Rate graphs
- Characteristics of a catalyst
- Catalysts and activation energies
- Enzymes – biological catalysts
- Reversible reactions
- How the changes in conditions (temperature, pressure and use of suitable catalyst) will affect the yield and rate of production of ammonia
- Optimal conditions of the Haber Process – manufacturing of ammonia industrially
- Displacement of ammonia from ammonium salts
19. Air and The Atmosphere
- Composition of unpolluted air
- Air pollutants (sources, adverse effects and how to reduce them)
- Acid rain (formation, adverse effects and how to reduce them)
- Catalytic converters
- Flue gas desulfurisation
- Depletion of the Ozone Layer
- Global warming due to greenhouse gases like carbon dioxide and methane
- Effects of global warming
20. Organic Chemistry
- Characteristics of a homologous series
- Fractional distillation of petroleum (also known as crude oil)
- Uses of the different fractions of crude oil
- Physical and chemical properties of alkanes
- Physical and chemical properties of alkenes
- Production of alkenes by cracking
- Physical and chemical properties of alcohols
- Physical and chemical properties of carboxylic acids
- Oxidation of alcohols to respective carboxylic acids
- Uses of ethanol
- Uses of esters
- Addition and condensation polymerisations
There you go. All the possible topics/concepts you might be tested for Paper 1 MCQ on 15th November 2019. Do study hard for it and aim to score 100% for it.
Now, if you do not know how (or simply too lazy or unmotivated) to revise and prepare for this final MCQ paper, we welcome you to join us in the upcoming annual Score 100% MCQ Workshop. This is the 11th year we are conducting this signature workshop to help students to ace their Chemistry. Let me help you.
Click the image below for more information and sign-up. Seats are extremely limited (5 seats left at the point of writing this blog post). So do take the necessary actions fast!
To Your Chemistry Success,
Sean Chua | Winners Education
PS: A quick note that we will be conducting our Score 100% O-Level Pure Chemistry MCQ Workshop on 9th November 2019 to help students to score full marks for their Paper 1 (MCQ Paper) with 30% weightage. We have consistently received positive feedbacks and glowing reviews for this annual workshop and this will be the 11th consecutive year that we are conducting it. Join us if you are committed to UP your overall Chemistry grade.
“This programme tells me the topics that I am weak in and it emphasises the importance of getting full marks for Chemistry MCQ. I have learnt to manage my time wisely, which is crucial in doing Paper 1 as I usually could not finish the paper. I learnt more about the strategies of doing MCQ and revise on key concepts. I hope I am able to get full marks and I will recommend this to anyone taking O-Levels.” Cher Yi Jia, Nan Hua High School