JC/A level/H2/H1/O level Chemistry Tuition@Kovan

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TO Master to PERFECTION before A’levels – Part 3

4. Electrochemistry
• Predict qualitatively how the value of an electrode potential varies with the concentration of the aqueous ion
*Could be a disguised change e.g.adding NaOH (aq) to ppt. Mn+.

Refer to our consolidated list last term

5. Chem Eqm
• Apply LCP to deduce qualitatively (from appropriate information)
the effects of changes in concentration, pressure or temperature, on a system at equilibrium.
• Deduce whether changes in concentration, pressure or temperature or the presence of a catalyst affect the value of the equilibrium constant for a reaction

E.g. Given Kc ↑ when temp ↓, predict if reaction is exo/endo.
6. Ionic Eqm
• Explain the choice of suitable indicators for acid-base titrations,given appropriate data
• Explain how buffer solutions (i)control pH (ii) describe and explain
their uses, including the role of H2CO3/HCO3– in controlling pH in
blood

3 main points.
With equations with SINGLEHEADED arrows

For exam based questions with solutions please contact @9863 9633

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Glossary of Terms

1. State
A concise answer with little or no supporting argument, e.g. a numerical answer that can be obtained ‘by inspection’ is required.

2. List
A number of points, generally each of one word, with no elaboration is required. Where a given number of points is specified, this should not be exceeded

3. Explain
Reasoning or some reference to theory is required (depending on the context)

4. Describe
State in words (using diagrams where appropriate) the main points of the topic. It is often used with reference either to particular phenomena (where answers should include reference to observations associated) or to particular experiments.

5. Discuss
A critical account of the points involved in the topic should be provided.

6. Outline
Be concise i.e. restrict the answer to giving the essentials only.

7. Predict
Make a logical connection between other pieces of information. Such information may be wholly given in the
question or may depend on answers extracted in an early part of the question.

8. Deduce
Used in a similar way as predict except that some supporting statement is required, e.g. reference to a law/principle, or the necessary reasoning is to be included in the answer

9. Comment
It is an open-ended instruction, inviting one to recall or infer points of interest relevant to the context of the question, taking account of the number of marks available.

10. Suggest
It is used in two contexts, i.e either to imply that there is no unique answer (e.g. in chemistry, two or more substances may satisfy the given conditions describing an ‘unknown’), or to imply that candidates are
expected to apply their general knowledge to a ‘novel’ situation, one that may be formally ‘not in syllabus’.

11. Find
Can be interpreted as calculate, measure, determine etc

12. Calculate
A numerical answer is required. In general working should be shown.
Note:The misuse of units and/or significant figures is liable to penalty.

13. Determine
It implies that the quantity cannot be measured directly but is obtained by calculation, substituting measured and known values of other quantities into a standard formula.

14. Sketch
When applied to graph work, the shapes and/or position o the curve need only be qualitatively correct but some quantitative aspects (e.g. passing through the origin, having an intercept at a particular value) may be looked for.

In diagrams, a simple and freehand drawing is acceptable but care should be taken over proportions and the clear exposition of important details.

15. Construct
Often used in relation to chemical equations where one is expected to write a balanced chemical equation,not by factual recall but by analogy or by using information in the question.

16. Compare
Both similarities and differences between things or concepts should be provided.

17. Classify
Group things based on common characteristics.

18. Recognise
Often used to identify facts, characteristics or concepts that are critical (relevant/appropriate) o the understanding of the situation, event, process or phenomenon.

For exam based questions with solutions please contact @9863 9633

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O Level Chemistry Tuition Singapore/Chemistry O Level Tuition/Tutor

2014 Secondary 4 Preparatory Course

11-Nov Mon 10.30am to 12pm 1.5 hrs Chemical Bonding 1

12-Nov Tue 10.30am to 12pm 1.5 hrs Chemical Bonding 2

13-Nov Wed 10.30am to 12pm 1.5 hrs The Mole 1

14-Nov Thu 10.30am to 12pm 1.5 hrs The Mole 2

15-Nov Fri 10.30am to 12pm 1.5 hrs Chemical Calculation 1

18-Nov Mon 10.30am to 12pm 1.5 hrs Chemical Calculation 2

19-Nov Tue 10.30am to 12pm 1.5 hrs Acids and Bases 1

20-Nov Wed 10.30am to 12pm 1.5 hrs Acids and Bases 2

21-Nov Thu 10.30am to 12pm 1.5 hrs Salts 1

22-Nov Fri 10.30am to 12pm 1.5 hrs Salts 2

If you need help in the above topics, please contact Angie @96790479 or Mr Ong 98639633

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O Level Chemistry Tuition Singapore/Chemistry O Level Tuition/Tutor

Power Revision

O Level Chemistry – 2 hrs Each Lesson

1. Atomic Structure/Ionic, Covalent and Metallic Bonding – 2 lessons
2. Formulae & Equation Writing – 1 lesson
3. Mole & Chemical Calculations – 2 lessons
4. Acids and Bases – 1 lesson
5. Salts – 1 lesson
6. Chemical Analysis – 1 lesson
7. Metals – 2 lessons
8. Periodic Table – 2 lessons

If you need help in the above topics, please contact Angie @96790479 or Mr Ong 98639633

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Speed of Reaction – Important definitions

1. the speed of reaction is the amount of reactant used up or the amount of product obtained per unit time.

2. Activation energy is the minimum energy that the reacting particles must possess for a reaction to occur.

3. An effective collision is a collision that successful in producing a chemical reaction.

4. A catalyst is a substance that increases the speed of a chemical reaction.

5. An enzyme is a substance that catalyses biochemical reactions.

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Ammonia – Important Definitions

1. A reversible reaction is a chemical reaction that can proceed in both the forward and reverse directions.

2. Haber process is an industrial process for making ammonia from nitrogen and hydrogen.

Operating conditions in the Haber process
Temperature – 450 deg C
Pressure – 200 – 300 atm
catalyst – Finely divided iron

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The Atmosphere and Environment – Important Definitions

1. Air pollution is the condition in which air contains substances that are harmful to living things or the environment. These substances are known as air pollutants.

2. A photochemical reaction is a chemical reaction caused by light or ultraviolet radiation.

3. Acid rain is rainwater with pH 4 or less than 4

4. Flue gases are waste gases produced when fossil fuels undergo commutation.

5. Chlorofluorocarbons CFCs are compounds containing the elements carbon, fluorine and chlorine.

6. The carbon cycle is the movement of carbon from carbon dioxide in the in the air through living things and back to the air again.

7. Greenhouse effect is the absorption of infrared radiation by some gases in the air which leads to atmospheric warming.

8. Global warming is the gradual warming of the Earth’s atmosphere due to the increased concentration of greenhouse gases in the atmosphere.

If you need help in the above topic, please contact Angie @96790479 or Mr Ong 98639633

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Petroleum

1. Petroleum is a non-renewable resource and there is only a limited amount of petroleum in the Earth.

2. Moet petroleum is used as fuel. Only a small amount is used as feedstock to make useful petrochemicals.

3. Gasohol is an alternative energy sources used as a fuel in motor vehicles.

4. Biogas is also used as an alternative energy source. It contain about 50% ethane.

5. Hydrogen can also be used as a fuel for cars.

If you need help in the Organic Chemistry, please contact Angie @96790479 or Mr Ong 98639633

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Important Definitions – Alkanes & Alkenes

1. Saturated hydrocarbon are compounds containing only carbon and hydrogen and having single bonds between carbon atoms.

2. Unsaturated hydrocarbon are compounds containing only carbon and hydrogen and having double bonds between carbon atoms.

3. Alkane series has a general formula CnH2n+2

4. Alkenes series has a general formula CnH2n

5. Structural formula is the chemical formula that shows how the atoms are joined together in a molecue.

If you need help in the Organic Chemistry, please contact Angie @96790479 or Mr Ong 98639633

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Important Definitions – Alkanes & Alkenes

6. Isomerism is the existence of two or more organic compounds with the same molecular formula but different structural formulae. These different compound called isomers.

7. A substitution reaction is a reaction in which an atom (or a group of atoms) in an organic molecule is replaced by another atom ( or group of atoms)

8. An addition reaction is a reaction in which an unsaturated organic compound combines with another substance to form a single product.

9. Cracking is a process in which a large hydrocarbon molecules are broken down into smaller molecules.

10. Polyunsaturated compounds are organic molecules that contain more than c=c bond.

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Alkanes

1. Saturated hydrocarbon are hydrocarbons with only single bonds between carbon atoms.

2. Unsaturated hydrocarbons are hydrocarbons with one or more double bond or triple bond between carbon atoms.

3. The alkanes are saturated hydrocarbons with the general molecular formula CnH2n+1 where n = 1, 2, 3, ……

4. Alkanes contain only single bonds between carbon atoms. Each carbon atom in an alkane molecule uses all its valence electrons in forming single bonds with four other atoms.

5. First four members of the alkane
Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10

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Alkenes

1. Alkenes are unsaturated hydrocarbons that contain one or more carbon-carbon double bond

2. The general formula of alkenes with one double bond is CnH2n

3. Naming of alkenes
Ethene C2H4
Propene C3H6
Butene C4H8

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Isomerism

1. Isomerism is where two or more organic molecules have the same molecular formula but different structural formula. These different molecule are called isomers.

2. Isomers have different melting and boiling points

3. Methane, ethane and propane do not have isomers.

4. Butane has two isomers
– Butane
– Methylpropane

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Chemical Properties of Alkenes Part 1

1. The functional group of alkenes is the carbon-carbon double bond (C=C).

2. Alkenes are more reactive than alkanes because of the presence of the double bond.

3. The combustion of alkenes produces carbon dioxide and water

4. Alkenes produce more soot than alkanes when they burn in air because a relatively higher percentage of carbon than the alkanes with the same number of carbon atoms.

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The Manufacture of Alkenes by Cracking

1. Alkenes are obtained by the cracking of petroleum fractions, such as the naphtha fraction.

2. Cracking is the process in which large hydrocarbon molecules are broken down into smaller molecules.

3. When an alkane molecule is cracked, a mixture of short-chain alkanes, alkenes and hydrogen are formed.
Example:
When the alkane C13H28 in naphtha is cracked, it is broken up into smaller alkane and alkene molecules

3. When an alkane molecule is cracked, a mixture of short-chain alkanes, alkenes and hydrogen
are formed.

Example:
When the alkane C13H28 in naphtha is cracked, it is broken up into smaller alkane and alkene molecules

4. The conditions used for cracking
(a) In industries, cracking is carried out by passing the petroleum fraction over the catalyst at high temperature. The process is called catalytic cracking.
(b) The conditions for catalytic cracking are:
• Temperature: 600°C
• Catalyst: Silicon(IV) oxide, SiO2, or aluminium oxide, A/203

5. In the school laboratory, catalytic cracking can be carried out using the apparatus as shown in the following diagram.

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