2010

Happy New Year 2010.

Enjoying my holiday at the moment.

Tar college Open day

If you want an affordable and quality education, come and find out more at Tar College Open Day.

Yew Shy Gin

On 2nd November 2009, three Utar students drowned after they were swept away by strong current during an outing to Batu Berangkai Waterfall, Kampar. (my hometown). One of them is Yew Shy Gin.
I used to go to this waterfall when I was a student. Well, this place is quite dangerous especially after it rains as there will be a water gush from the top.

By the way, Shy Gin did her A-level in Tar College.
She was my former student from the class of SN7c.

Rest In Peace

My condolences to her family.

Trial Exam Sept 2009 Paper 1 and 2

Sorry, for the long silence. Take me some time to look for the soft copy.
Paper 1
Ans for Paper 1
Paper 2
Ans for Paper 2

Trial Exam Sept 2009 Paper 4 and Paper 5

Trial Paper 4 2009

Marking Scheme Paper 4

Trial Paper 5 2009

Marking Scheme Paper 5

A2 Quick Revision Notes

Quick revision downloaded from lanther.co.uk

http://www.4shared.com/file/123745687/3d38ace0/A2_notes.html

Video on Nanotechnology

For those who want to watch again the video on nanotechnology which I had shown in my previous class , please click the link below:

http://www.youtube.com/watch?v=JqMh5NYsRck
http://www.youtube.com/watch?v=8Kg_Lyg_qcM&feature=related

Symbols in marking scheme and guide to writing a good answer

Symbols used in marking scheme:

/ - means that the responses are alternatives and either answer should receive full credit.
( ) - means that a phrase/word is not essential for the award of the mark, but helps the
examiner to get the sense of the expected answer.
Phrases/words in bold - means that the phrase or the actual word is essential to the answer.
Ecf (error carried forward)- means that a wrong answer given in an earlier part of a question is
used correctly in answer to a later part of the same question.

Guide to writing a good answer

1) Make the meaning of your answer clear to the examiner.
2) Make sure that the answer makes sense.
3) Answers must be in the correct context. In other words, your answers must answer the
questions.
4) Write legibly – the examiner must be able to read your handwriting and the font of your
handwriting should be big enough for them to read easily. Don’t forget, most examiners are
40s or 50s something and many of them are short-sighted.
5) Your words or sentences should have the accurate use of spelling, grammar and punctuation
in order to make the meaning clear.
6) Organise information clearly and coherently.
7) Use specialist vocabulary when appropriate.

Change of ph to f

CIE has changed the following terms:
New term for sulphate is sulfate
thiosulphate is thiosulfate
sulphite is sulfite
sulphur is sulfur
disulphide to disulfide

Xtreme link

Change of Xtremepaper link

http://www.planet-master.com/

Many thanks to you, Leong Seek for your information

Important Notice

To all students taking AS and A2 Examinations:

You are reminded again that you are not allowed to discuss anything about the question papers in the forum or blog within 24 hours after your paper. Don't forget some of the candidates in other parts of the world have not sat for the papers due to the different time zones. Failure to observe this rule means you are in trouble. Good luck

Paper 1 Question and Answer April 2008

Paper 1 April 2008

Answer Paper 1 April 2008

Think before you use

Waste decomposition Rate

Styrofoam is not composed
Plastic bottle takes at least 1 million years
Disposable diaper 500 to 600 years
Aluminium tin 200 to 500 years
Leather shoes 40 to 50 years
Newspaper 1 month

Source : Star

Never judge a book by the cover

I was truly astounded by the talent of Susan Boyle when I watched her singing on the Britain's Got Talent (from Youtube). Her performance received a standing ovation from the live audience and later took the world by storm. The numbers who watched her videos on her audition have climbed to almost 200 millions and the figure is still growing.

What's so special about her? She is a 47 years old lady whose appearance is #@?/... but possess a golden voice. Watch her sing and you would understand what I meant.

http://www.youtube.com/watch?v=9lp0IWv8QZY

Organic A2 Reactions

AS Practical Guide II

Guide to Potassium manganate(VII) titration

· For KMnO4 titration, no indicator is added because KMnO4 acts as its own indicator and it would change to pale pink colour at the end point.
· KMnO4 titration is used to determine the concentration of Fe2+ (Iron(II) ions) , H2O2 (hydrogen peroxide) and C2O42- (ethanedioate).
· KMnO4 titrations must be carried out in acidified condition because in neutral or alkaline solution, brown solid MnO2 is formed and as a result it would be difficult to detect the end point.
· To acidify, sulphuric acid is used and not other acids such as hydrochloric acid and nitric acid because the chloride ions or nitrate ions would also be oxidised.
· Most KMnO4 titrations should be carried out at room temperature except titration involving C2O42- which is normally carried out at 70 oC. For ethanediote, any temperature lower than 70 oC could cause the precipitation of MnO2.
· Titration using KMnO4 solution should be carried out slowly. A brown precipitate of MnO2 is formed when KMnO4 is dropped from the burette too quickly.
.
Guide to Iodine-thiosulphate titration
· Starch is used as an indicator in this titration
· The starch solution should not be added at the beginning of the titration. The reason is at this stage, there is a high concentration of iodine and iodine would be adsorbed onto the starch molecule.
· The starch solution should be added towards the end of the titration when the reaction mixture turns pale yellow. (Warning: not too pale as you may overshot the endpoint)
· The starch solution will produce a dark blue colour with iodine.
· At the end point ,the solution turns colourless.
· Be careful, the solution may become blue again due to the atmospheric oxidation of iodide (from potassium iodide). You shouldn’t continue titrating again.

Good luck

The AS Mock exam started today. Good luck to those who are taking the exam. I would be extremely busy these coming few weeks. First, I am involved in the time-table committee. I can foresee myself sitting for hours to come out with the new timetables for both the students and the teachers for the next Semester. The only good thing is I can prepare my own timetable to my likes.

Second, 'tons' of students' answer scripts waiting for me. I have five classes under my charge. Not only that, with different styles of handwriting: artistic type, doctor type, miniature type, hilly type (the one with the gradient at 45 degree), my eyesight power will double after that.

Third, need to plan for the coming AS practical exam. (Please don't ask me what will be coming out. Even I am 'tortured' or offered a bribe , I won't reveal a single thing.)

Fourth, need to complete my new book before the deadline.

Fifth...sixth...etc. Who said teaching is easy? Salary is low and plenty of work. The only reward is a good karma or maybe a place in the heaven. That would keep me motivated when I think of that.

Important AS equations for Inorganic Chemistry

Practical P31/32 (Part 2)

Maximum error

Maximum error is usually marked on the glassware.

Burette
• A pipette has a maximum error of 0.05 cm3 in each measurement.

Calculation of percentage error

Percentage error = (maximum error ÷ quantity measured ) x 100%

Reading burettes
A burette is graduated in divisions every 0.1 cm3.
Using the half-division rule, the estimation is 0.05 cm3.
Burette is recorded to two decimal places with the last figure either ‘0’ or ‘5’.
The maximum error in each measurement = 0.05 cm3.
The overall maximum error in any volume measured always comes from two measurements, so
the overall maximum error = 2 x 0.05 cm3 = 0.1 cm3.
In a titration, a burette will typically deliver about 25 cm3 so the percentage error is small.

Percentage error = (2 × 0.05 ÷25.00) x 100% = 0.4%

The percentage error becomes more significant when burette is used to deliver small volume
For delivery of 2.50 cm3,

Percentage error = (2 × 0.05 ÷ 2.50)× 100% = 4%

Practical 31/32 Learn More (Part 1)

1. Titres should be within 0.20 cm3.
2. Candidates were expected to produce a single table.
3. The table should include correct headings and units.
4. Burette readings and the volumes added recorded to the nearest 0.05 cm3.
5. Select appropriate scales when plotting a graph
6. In plotting graph, a line should be best-fit straight line or a smooth curve.
7. A graph should contain at least five ponts.
8. Answer for calculation should be given to at least 3 significant figures
9. Thermometer readings and temperature differences expressed to the nearest 0.5 °C,
10. All weighings and the masses of the solid used should be recorded consistently to 1 decimal place or 2 decimal place depending on the sensitivity of the electronic balance. The balance in our lab can measure up to 2 decimal points.
11. To calculate mcT equation, the m is the mass of solution not the mass of solid.
12. +ve sign or –ve sign should be written on the H value.
13. Common error in thermochemistry experiments:
· heat loss/gain with the surroundings
· acid spray from the vigorous reaction
· the use of a thermometer calibrated by 1 °C
14. Suggested improvement for thermochemistry experiments :
· Suitable additional insulation or use of a lid
· Use of a thermometer with closer graduation or use of a digital thermometer

Answers for Trial Paper 2008 Aug

Answer Paper 1 2008 Aug

Answer Paper 2 2008 Aug

FRIM Trip

The Science and Maths Society (SMS) organized a trip to FRIM on Sat (28/2/09). I was invited to go along since I am the advisor for the society. This was my second trip to FRIM.

Here we come, leeches and mosquitoes

Assault on the forest

Canopy walk Can’t miss that shot

A view from the canopy

‘Trigonal shape’, that’s what I see. This was related to me by a student from SN9d when she saw this flower.

A view of 'delocalised electrons' in the nature

Safe and sound. Apart from some mosquitos’ bites, no one was victim of the leeches. Maybe our blood is a bit acidic after a strenuous climb or this is not the leech season.

Achieve enlightenment in the forest. I am in the 'nirvana' state. In chemistry, it is equivalent to triple point, a state in which solid , liquid and gas are in equilibrium.

I am the new spiderman

Mock Exam Paper 1 and Paper 2 2008 (Aug)

Mid-course exam (Trial exam for AS) is coming soon. You can start practising some of the trial exam papers. Answers for the papers will only be published one week later.

Paper 1 2008

Paper 2 2008

Acidosis and alkalosis: good to know more

Remember, I mentioned two pH related diseases acidosis and alkalosis in our lesson when I taught buffer solutions and explained why it’s important for our body to maintain a fairly constant pH. Here’s more information about these diseases. This information is just for your general knowledge.

A healthy person has a blood pH close to 7.4.
Acidosis is a state of excess acidity in the blood and occurs when blood pH falls below 7.35 Alkalosis is a state of excess alkalinity when blood pH is over 7.45.
When the blood pH falls below 7.0, it is diagnosed as severe acidosis and in severe alkalosis it may rise above 7.5. Acidosis is more common than alkalosis.

pH in our blood or fluids is controlled by three following mechanisms
1. Blood's protein that's acts as a buffer that limits changes in acidity.
2. Lung, which give off carbon dioxide to prevent accumulation of carbonic acid.
3. Kidneys which manufacture hydrogen carbonate ions and retain acids or bases.

Causes of Acidosis:
1. Kidney failure reduces the efficiency to regulate acidity.
2. Starvation produces excessive acid due to metabolism of large amounts of body fat which produce lactic acid
3. Increased protein intake – eat too much meat
4. Ingestion of large amounts of acidic substances eg pickled fruits
5. Diabetes

Causes of Alkalosis:
1. Severe diarrhea may cause excessive loss of basic fluids
2. Loss of carbonic acid because of fast or rapid breathing.
3. Excessive vomiting causing loss of hydrochloric acid (stomach content)
4. Excessive intake of antacids to relieve acid in the stomach.

Chemistry resources

Recently, some students asked me to recommend them some good chemistry websites. For me, I usually look at these two websites.

LearnNet

Chemguide

Please take a look at these sites .
Do you find them useful? Please comment.

Dare to take this challenge

Take this challenge and download the past year questions for the Chemistry Olympiad UK. Give yourself a Chemistry test. Reminder: Look at the answers only after you have tried the questions.
Chemistry Olympiad 2008 Examination

Answer

Important AS Definitions Part II

Activation energy is the minimum energy required by colliding particles to start off a reaction.


A catalyst is a substance which changes the rate of a chemical reaction without itself undergoing any chemical change at the end of the reaction.

Homogenous catalyst is a catalyst in which the physical state is in the same phase as the reactants.

Heterogenous catalyst is a catalyst in which the physical state is in the different phase as the reactants.

Increase the concentration of reactants will increase the rate since there will be more molecules per unit volume resulting in an increase in the collision frequency between the reactants. This leads to higher number of effective collisions.

Increase in the temperature will increase the rate since at higher temperature the particles gain more kinetic energy resulting an increase in collision frequency at higher temperature. In addition, more molecules have kinetic energy greater than or equal to the activation energy. Consequently, the number of effective collisions increases.

A catalyst operates by providing an alternative route of lower activation energy for the reaction.

Geometric isomers are compounds with different spatial arrangement due to the restriction in the rotation about the double bond in an alkene. In geometric isomers, two different groups at each end of the double bond can either be on the same side (cis) or on opposite sides (trans)

Optical isomers are mirror images that have the same geometric and structural formula, but cannot be superimposed onto one another.

Cracking is a process to break long alkane into a shorter alkane and an alkene. Hydrogen may also be produced. Thermal cracking requires temperature between 400°C to 900°C and high pressure whereas catalytic cracking requires a zeolite catalyst and a temperature of about 450°C. The purpose of cracking is to form extra gasoline and to produce alkenes with higher commercial value

Homolytic fission is the breaking a covalent bond in which one electron goes to each atom to form free radicals.

Heterolytic fission is the breaking a covalent bond in which one atom takes both electrons forming negative and positive ions.

A free radical is a highly reactive atom or molecule with an unpaired electron.

An electrophile is an electron-deficient species that can form a new covalent bond by accepting an electron pair provided by the carbon compound. Example : positive ion such as hydrogen ion or nitronium ion and a polar molecule with a d+ charge

A nucleophile is an electron-rich species with a lone pair of electrons that can form a new covalent bond by donating a pair of electrons to the electron deficient carbon atom. Example : negative ions with at least a lone pair.

Red, red....almost everyone is red

Class SN9p.. must act cute, you know

SN9deg..........wonder who's the 'old' student on the right hand corner in the first row?

Even the lecturers are not spared from red

SN9deg classes... even Indian students joined in the fun

SN 9pq .........very sporting ....is it the hand sign for the bull horn?

Year of the OX, ma.

Download past year papers for any exams

I have discovered two websites that you can download past year papers for a number of international examinations such as Cambridge , AQA, TOEFL , SAT, ACCA etc...

Xtreme
Black

Gong Xi Fa Chai

Disclaimer:
I would not be responsible for the content of it.

Organic AS Reactions (Spider Diagram)

Spider diagram is one of the methods used in mind mapping. Using spider diagram to study the organic reactions is an effective method to remember reactions. You can also see the links between the functional groups. You can magnify it by clicking the diagram.

My dear students, don't forget to wear red or pink this coming Friday 23/1/09 in conjunction with the Chinese New Year festival. Hopefully, it will bring us luck, success and happiness.

My new Chemistry workbooks

Last year, I wrote some SPM workbooks. It was definitely not an easy job. I had to toil away countless night to finish the books. Finally, the books are ready and they are available in the bookstores now.

Important AS definitions (Part I)

Atomic number or proton number is the total number of protons in the nucleus of an atom.

Mass Number or nucleon number is the total number of protons and neutrons in the nucleus of an atom.

Isotopes are atoms with the same number of protons but different numbers of neutrons.

The relative isotopic mass is the mass of one isotope of an element compared to 1/12 the mass of the 12C isotope.

The relative atomic mass is the average mass of one atom compared to 1/12 the mass of the 12C isotope.

First Ionisation Energy is the energy required to remove one mole of electrons from 1 mole of gaseous atoms to produce 1 mole of gaseous unipositive ions.

First Electron Affinity is the energy liberated when one electron is added to each atom in 1 mole of gaseous atoms to form 1 mole of gaseous ions with a uninegative charge.

Electronegativity is the power of an atom to attract bonding electrons.

Oxidation is loss of electrons. Remember OIL RIG
Reduction is gain of electrons.

Oxidising agent is a substance which removes electrons from another substance and itself is reduced.

Reducing agent is a substance which gives electrons to another substance and itself is oxidised.

Disproportionation is simultaneous oxidation and reduction of one species in a chemical reaction.

Metallic bond is the electrostatic attractions between the positive ions and a 'sea' of delocalised valence electrons surrouding the positive ions.

Ionic bond is the attraction between the oppositely charged ions formed by transfer of one or more electrons from one atom to another.

Covalent bond is the attraction of the nuclei for the shared pair of electrons between two atoms.

Sigma bond is the covalent bond formed by ‘head on’ overlap of atomic orbitals.

Pi Bond is the covalent bond formed by sideways overlap of atomic orbitals.

Valence Shell Electron Pair Repulsion (VSEPR) Theory states that the shape of a molecule is determined by the repulsion between the electron pairs in the valence shell. According to the VSEPR , the electron pairs will arrange themselves so as to be as far apart as possible.

Polarising power is the ability of a positive ion to attract electrons away from a negative ion.

Dipole-Dipole Forces are intermolecular attractions between molecules which are permanently polarised.

Hydrogen Bond is the electrostatic attraction between a hydrogen atom which is bonded to a very electronegative atom and an electronegative atom of a neighbouring molecule.

Van Der Waals Forces are intermolecular forces of attraction which arise from temporary
dipoles in molecules.

Standard Enthalpy Of Formation is the enthalpy change when 1 mole of the substances is formed from its elements at their natural states at 298K and 1 atm pressure.

Standard Enthalpy Of Combustion is the enthalpy change when 1 mole of an element or compound is completely burned in oxygen at 298K and 1 atm pressure.

Standard Enthalpy Of Neutralisation is the enthalpy change when 1 mole of water is formed from the reaction between an acid and a base at 298K and 1 atm pressure.

Hess’s Law states that the total energy change resulting from a chemical reaction is dependant only on the initial and final states of the reactants and is independent of the reaction route.

Bond energy is the energy required to break 1 mole of bonds from gaseous molecules into gaseous atoms.

Reference : Stephen Oakes

Economy rice in TAR college canteen

How much does it cost for a plate of rice with 4 dishes? You won't believe it. RM2.20. I repeat RM2.20. Yummy...that's my lunch.