“Leap from O-Level Chemistry to A-Level H2 Chemistry”

To qualify for taking up H2 Chemistry, some JCs have the requisite that students must have a minimum B3 grade for O-Level Pure Chemistry or A2 for Combine Science Chemistry. There’s an obvious reason for this condition as A-Level H2 Chemistry syllabus is demanding in terms of content. If you are posted to a JC, lessons usually start in mid February and are you aware that your promotional examination can start as early as mid September. This means you only have about 6 months of studying period. Do not expect any revision as most lecturers are rushing to complete the syllabus for examination.

JC1 will be over before you know it! Imagine getting used to the new school environment, new friends, new lecture-tutorial system, new expectations from your parents, friends and school, all these can be really stressful if you did not manage well. Every year, my students asked me the same questions about JC life, in particular,

Should I take H2 Chemistry since I only scored an A2 for O-Level Pure Chemistry?
What’s so challenging about H2 Chemistry since I have learnt Chemistry at O-Level? Isn’t it just an add-on?
How can I prepare myself to handle H2 Chemistry confidently?

I would like to share my experience as a Ten Years Series author for O-Level and A-Level Chemistry to the above questions and more. After having taught students from almost every JCs, I come to understand the challenges, the struggles JC1 students go through and by knowing how to handle the transition from O-Level to A-Level effectively, not only do you have a memorable 2 years of JC, it will also pace you for tertiary education. Join me in this free talk! I look forward to meeting you!

Title of talk: “Leap from O-Level Chemistry to A-Level H2 Chemistry”

Date: 6 Feb 2018 (Tuesday)

Time: 7 – 830pm

Venue: Winners Education Centre Pte. Ltd. Blk 261, Waterloo St, #03-21, Waterloo Centre Singapore 180261

For: Students (& Parents) who have decided on or considering H2 Chemistry as an A-Level subject

Registration is closed. If you would like to attend the 2019 session, please SMS us at 9828 7357

Small group sharing with questions and answers session from parents/students at the end of talk. Parents are enlightened and students are mentally ready to start the tricky and rigorous JC1 curriculum.

O-Level Pure Chemistry Final Revision: Score 100% Chemistry MCQ Workshop (9th Year!)

Do you lack the motivation to continue with thorough preparation for your Pure Chemistry MCQ paper when you just study for Chemistry structured paper 15 days ago?
Are you uncertain of how to prepare effectively for your MCQ?
Are you simply going to flip through your notes and textbook on the eve of your MCQ paper and thinking that it is sufficient for you to continue in the paper?
Are you overly confident of your ability that you do a slipshod revision instead of paying to details, recapping essential concepts?

For the 9th consecutive year, Score 100% O-Level Pure Chemistry MCQ Workshop has helped hundreds and hundreds of students from more than 170 schools to prepare Chemistry MCQ with

the right mindset (regardless of how you think you have fared for Paper 2)
tested and proven strategies to score confidently in MCQ within 60 minutes
highlighting of the common mistakes
the strategies to complete the MCQ paper fast and accurate even with time for checking (This is the secret why students can score 100% for Chemistry MCQ, you have time to check our answers while your friends struggle to complete the questions!)

Many people know me as the Master Trainer for Chemistry in Winners Education as well as Ten Year Series book author.

Over the last 18 years, I have coached thousands and thousands of students from over 170+ schools to achieve the marks they truly deserve. I have also rekindled their interest in Chemistry so much so that many of them are furthering their study in chemistry-related courses and in fact, a handful of them will be joining the booming chemical industry.

Join me and a group of committed students on 11 November 2017 (Sat) for Score 100% Pure Chemistry MCQ Workshop by clicking on the button below!

“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

“It has benefited me by giving me the chance to practise. It has also helped me to revise and remind me what I have forgotten.” Ryan Lee, Chung Cheng High School (Main)

It is good that Sean has organized this workshop to focus on the MCQ of Chemistry paper as it is often a paper that teachers and students alike will neglect. Through the workshop, he covers tricky and common MCQ questions, which is very helpful. His cheerful and lively teaching approach learns to keep everyone awake and in focus. Thanks Sean for everything! Definitely recommended to other students in future. Edna Chan Zhi Yin, Hougang Sec School

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:

Fuels & Crude Oils
Homologous Series & Functional Groups
Naming of Organic Compounds
Isomerism
Alkanes
Alkenes
Alcohols
Carboxylic Acids
Esters
Macromolecules
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

O-Level Chemistry: 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) $\rightarrow$ 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, NO_x(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) $\rightarrow$ 2NO(g)

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

2NO(g) + O₂(g) $\rightarrow$ 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. Feel free to share this blog post with your friends.

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PS: Under related articles below, there are several blog post discussions and questions related to Air & Atmosphere. You can also do a keyword search using the search box at the top right hand corner.

O-Level Chemistry Question: Periodic Table & Group Trends

I received an email from Mahrukh, one of the reader of SimpleChemConcepts.com. 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:

Question:

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.

O-Level Chemistry: Strength versus Concentration of Acids

In the previous blog post, we have watched a video on the difference between Strength of Acids and Basicity of Acids.

If you have missed it, you can click HERE to watch it.

Today, we are going to discuss another misconception by many students studying basic Chemistry.

It is very important not to confuse the Strength of Acids with the Concentration of Acids.

I have observed that many of my GCE O-Level and IGCSE Sec 3 and Sec 4 Pure Chemistry Tuition Class students are confused by what they have learned from their school’s Chemistry teachers or previous home-based Chemistry tutors. It usually take me some effort to re-align their concepts and associated keywords.

As we have learned in the previous blog post, Strength of Acids refers to the extent of dissociation (or ionisation) of an acid. We will see words like “STRONG” and “WEAK“.

Concentration of Acids is different. It refers to how much of an acid (the solute) is dissolved in the solution. We will see words like “CONCENTRATED” and “DILUTE“.

Note that the strength of an acid is not affected by its concentration.

A dilute acid solution is not the same as a weak acid solution, and a concentrated acid solution is not the same as a strong acid solution.

i.e Dilute Acid $\neq$ Weak Acid

i.e Concentrated Acid $\neq$ Strong Acid

A strong acid will dissociate completely regardless of its concentration (whether it’s dilute or concentrated).

A weak acid will dissociate partially regardless of its concentration (whether it’s dilute or concentrated).

The term concentration is actually a concept covered in the topic of Mole Concepts or Mole Calculations.

The concentration of a solution is given by the amount of a solute dissolved in a unit volume of the solution.

Recall that a solution is made up of a solute and a solvent i.e. Solution $\equiv$ Solute + Solvent

As such, concentration of an acid can be easily changed!

You can decrease the concentration of an acid solution by adding more solvent to it.

You can also increase the concentration of an acid solution by adding more solute to it.

However, the strength of an acid cannot be changed!

A strong acid like HCl (aq) will always dissociate completely to produce a high concentration of hydrogen, H⁺ ions, regardless of whether the solution is dilute or concentrated.

A weak acid like CH₃COOH(aq) will always dissociate partially to produce a low concentration of hydrogen, H⁺ ions, regardless of whether the solution is dilute or concentrated.

Hope the above explanation is clear to you.

Together with the previous blog post, i have discussed on the difference between these three common terminologies used in the topic of Acids and Bases, namely:

Strength of Acids $\neq$ Basicity of Acids $\neq$ Concentration of Acids

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

Feel free to share this blog post with your friends who needs help in mastering Chemistry.

PS: You can do a search on the top right hand corner for more discussions and questions on Acids and Bases or select from the suggested blog posts under Related Articles below.

PPS: If you are based in Singapore and want to master Acids, Bases and Preparation Salts, i will be conducting an annual Topical Chemistry Revision Workshops during the June School Holidays. You can get in touch with us at PassWithDistinction.com to find out more.