Master O-Level Organic Chemistry in 2 Days!

I am Sean Chua, Master Trainer for Chemistry in Winners Education. Many students and parents also know me as the Ten Years Series author for O-Level & A-Level Chemistry.

Do you know there are less than 3 months to the O-Level Pure Chemistry Paper 2?

What this means is ‘Are you ready in your basic Chemistry concepts and application skills to score confidently in this year O-Level Chemistry examinations?’

I have been conducting the Organic Chemistry Topical Workshop since 2008 to help struggling students to

  • Summarize large junk of information into digestible bits
  • Understand this major topic clearly
  • Solve data-based application questions, guaranteed to be tested in examinations
  • Reduce memory work to a minimum
  • Score as high as possible in this heavy weighting topic!

Some of you might wonder about the effectiveness of this workshop since it is so near to O-Levels!

This is precisely the reason why I am still conducting this workshop during this period as most schools teach Organic Chemistry as the last topic in a rush rush manner and most students are unable to understand, find it confusing.

Are you one of them?

Since Organic Chemistry consists of many small subsections, many students are overwhelmed with the huge amount of content and thus lose confidence in their Chemistry.

“She can understand your lesson very well and for the first time, she says she likes Chemistry. Thank you for rekindling her interest in Chemistry. She has also expressed her interest in the weekly class.” 
Mr Cher, Father of Cher Yi Jia, Nan Hua High School, D7 to A2 in 4 months! 

I will be covering 100% of O-Level Organic Chemistry. It includes the following:

  1. Fuels & Crude Oils
  2. Homologous Series & Functional Groups
  3. Naming of Organic Compounds
  4. Isomerism
  5. Alkanes
  6. Alkenes
  7. Alcohols
  8. Carboxylic Acids
  9. Esters
  10. Macromolecules
  11. Application Questions

Organic Chemistry Workshop

Date & Time: 9 & 10 August 2017, 9am to 1pm

Bonus Booster Session

Date & Time: 31 August 2017, 10am to 1pm

Venue: 261, Waterloo Centre, #03-21, Singapore 180261

Chemistry Phenomenon: Nitrogen Dioxide as an Air Pollutant

Being a Chemistry Trainer and also a fellow cyclists (yes guys, i love to cycle), i read this local Straits Times Newspaper article with interest.

Seems like our Nitrogen Dioxide, NO2(g) level within the lower atmosphere level is quite high in Singapore.

NO2(g) is considered a major air pollutant which has the following harmful effects:

1) eye and lungs irritation and causes breathing difficulties

At high levels, it may even lead to inflammation of the lungs i.e. bronchitis

2) acid rain consisting of Nitric Acid HNO3 that is highly corrosive

In the presence of oxygen in the air, nitrogen dioxide is converted to nitric acid via the following chemical equation:

4NO2(g) + 2H2O(l) + O2(g)  4HNO3(aq)

Nitric acid corrodes buildings and harms aquatic life and plants.

Do you know that due to acid rain, the Statue of Liberty in the United States of America had been badly corroded. In the year of 1983, the US Government launched a campaign to restore this historical figure of US? Chemistry in action indeed!

NO2(g) is formed due to 2 main sources:

1) Lightning activities (which we have no control over since it is a natural source and it is NOT a daily source)

2) Vehicle exhaust fumes where high temperature around vehicles engine (which is a man-made source) causes 21% O2(g) and 78% N2(g) in the air to react to form oxides of nitrogen, NOx(g) which is mainly nitrogen monoxide, NO(g) and nitrogen dioxide, NO2(g).

Nitrogen reacts with oxygen at high temperature to form nitrogen monoxide or nitric oxide, NO(g).

N2(g) + O2(g)  2NO(g)

Nitrogen monoxide reacts with oxygen to form a brown colour gas called nitrogen dioxide, NO2(g).

2NO(g) + O2(g)  2NO2(g)

From the article, it shows that as concentration of air particulates (unburnt hydrocarbons) increases due to incomplete combustion of fossil fuels in vehicle exhaust fumes, there is also an increase in the concentration of nitrogen dioxide, NO2(g).

Since the satellites images have shown that the recent haze in Singapore is not from Indonesian fires (slash and burn method), it should be from the amounts of vehicle exhaust fumes produced locally on a daily basis.

  • More vehicles running on the roads
  • More incomplete combustion of fossil fuels
  • More unburnt hydrocarbons being produced
  • More nitrogen dioxide is also being produced
  • As such, the amount of unburnt hydrocarbons and the amount of nitrogen dioxides are highly correlated in a city which has a large number of vehicles running on the ground.

Time to ponder about if Singapore should encourage less driving….for our health and environment.

This is a good case study for GCE O-Level Pure Chemistry and Combine Science Chemistry students in Singapore to put their concepts learned in school into actual practice and application.

Same applies to Chemistry students worldwide doing other syllabus. This can be particularly severe in large cities, where traffic is heavy.

I hope you find the content easy for your understanding and if you have any questions, leave me a comment below.

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#Haze #HazeInSingapore #ChemistryConcepts #ChemistryPhenomenon #OLevelChemistry #PureChemistry #ChemistryInAction #Chemistry #EverydayChemistry #Geography #AirPollution #AirAndAtmosphere

O-Level Chemistry Question: Periodic Table & Group Trends

I received an email from Mahrukh, one of the reader of She is a Chemistry student and asked me about an examination question regards to the topic of Periodic Table & Group Trends.

I have decided to take this opportunity to discuss this question by her with a blog post today so that more students can benefit from it.

Her question as follows:


Sulfur and selenium, Se, are in the same group of the Periodic Table. From this, we would expect selenium to form compounds having the formulae

A) Se2O, Na2Se and NaSeO4

B) SeO2, Na2Se and NaSeO4

C) SeO2, Na2Se and Na2SeO4

D) SeO3, NaSe and NaSeO4

Regarding your question, this should be covered under “Periodic Table & Group Trends” in most Chemistry Syllabus in different countries.

The concept that she is being asked is known as “Same Group Properties“.

Elements in the same Group of the Periodic Table will have the same number of valence or outermost shell electrons.

As such, elements in the same Group of the Periodic Table would tend to form compounds with similar chemical formula.

Sulfur is a Group VI element and has 6 valence electrons.

  • It forms SO2 – so we expect SeO2 to exist.
  • It forms Na2S – so we expect Na2Se to exist.
  • It forms Na2SO4 – so we expect Na2SeO4 to exist.
  • As such, the answer will be option (C).

    Hope the above explanation is useful to you.

    PS: If you are not sure why we have the following chemical formulae (SO2, Na2S, Na2SO4)  in the first place, you can revise via this blog post on Writing Chemical Formulae of Ionic Compounds and Covalent Substances.

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    Feel free to share these videos with your friends who needs help in mastering Chemistry.