O Level Chemistry & IP Chemistry Notes by 10 Year Series Author - Chemistry Specialist

O Level Chemistry Made Easy

O-Level Chemistry: An Introduction to Organic Chemistry

Organic Chemistry by O-Level and IP Chemistry Tuition Class by Sean Chua.

Organic Chemistry is the study of organic compounds.

Organic compounds are compounds which contain the element carbon. Most organic compounds also contain hydrogen. Organic compounds which contain carbon and hydrogen only are known as hydrocarbons.

Organic compounds may also contain other elements such as chlorine, nitrogen, oxygen, etc.

Do note that there are some exceptions. Carbon monoxide (CO), carbon dioxide (CO2), calcium carbonate (CaCO3), etc are not classified as organic compounds even though they contain carbon.

In this post, we will look at the following basic fundamentals when it comes to organic chemistry:

  • Homologous Series
  • Functional Group
  • Naming of Organic Compounds
  • Formulae

A) Homologous Series

A homologous series refers to a family of organic compounds with the same general formula and similar chemical properties.

Do note that some textbooks defined homologous series as a family of organic compounds with the same functional group and similar chemical properties. This sounds a bit off considering that alkanes homologous series does not contain any functional group.

The homologous series covered in GCE O-Level Pure Chemistry syllabus (and other Sec 4 IP Chemistry syllabus) in Singapore are: Alkanes, Alkenes, Alcohols and Carboxylic Acids.

Organic compounds in the same homologous series have the following characteristics:

  • Represented by a General Formula
  • Regularly increasing relative molecular masses from one member to the next member
  • Can be prepared by similar methods
  • Gradual change in physical properties from one member to the next member
  • Similar chemical properties
  • Same functional group (except alkanes homologous series)

B) Functional Group

A functional group is defined as an atom or a group of atoms that gives a molecule its characteristic properties.

All molecules containing the same functional group will behave similarly towards the same chemical reagents, i.e. they have the same chemical properties.

Following are some homologous series and their functional groups that are covered in the Pure Chemistry syllabus:

  • Alkanes – Do not have any functional groups. There are only C-C and C-H covalent bonds in the molecule.
  • Alkenes – Contain the carbon-carbon double bond, C=C.
  • Alcohols – Contain the hydroxyl group, -OH.
  • Carboxylic acids – Contain the carboxyl group, -COOH.

C) Naming of Organic Compounds

The naming of organic compound is divided into three parts:

Part 1: Length of the parent chain i.e. the number of carbon atoms in the longest continuous (unbroken) chain [also known as the Prefix]

Prefix meth- eth- prop- but-
Number of carbon atoms in molecule 1 2 3 4

Part 2: Functional Group found in main parent chain [also known as the Suffix]

Homologous series alkane alkene alcohol carboxylic acid
Suffix -ane -ene -ol -oic

Part 3: Side group that are attached to the main parent chain [also known as Substituent]

Substituent -Cl -Br -I -CH3
Name of side group chloro bromo iodo methyl

 

For example, ethene is an alkene with two carbon atoms per molecule.

Ethene - Full Structural Formula
Full Structural Formula of Ethene

For example, propanol is an alcohol with three carbon atoms per molecule.

Propanol - Full Structural Formula
Full Structural Formula of
Propanol

D) Formulae

They are four types of formulae that we can use to represent a particular organic compound. This also means that you will be tested in Chemistry examinations on all four types of formulae which are:

  • Empirical  formula which is the simplest whole no. ratio of atoms of each element
  • Molecular formula which is the total no. of atoms of each element in each molecule
  • Structural formula which shows how atoms are arranged in the molecule
  • Full Structural formula which shows all the bonds between atoms in a molecule

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.

Do stay tuned to the upcoming posts as we will be looking at more key concepts in Organic Chemistry as well as some GCE O-Level Pure Chemistry and Sec 4 IP Chemistry examination questions.

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

PPS: If you need help with your O-Level Pure Chemistry and IP Chemistry, do join us in our weekly O-Level Pure Chemistry & IP Chemistry Tuition Class. Consistency is key to master Chemistry.

O Level Pure Chemistry . IP Chemistry June Holidays Intensive Revision Programme

Every year since 2008, our annual Pass With Distinction Revision Workshops for all Sec 3 and Sec 4 O-Level Pure Chemistry, IP Chemistry students have helped many to achieve a breakthrough in their Chemistry.

What is covered during the June Holidays?

The following key topics will be covered in the following workshops:

CM 1:  Chemical Bonding

CM 2:  Acids, Bases & Preparation of Salts

CM 3: Qualitative Analysis

CM 4: Mole Calculations

CM 5: Rate of Reaction & Energy Changes

CM 6: Redox & Electrolysis

CM 7: Organic Chemistry

“I scored an A1 because you told us that it’s not all about doing practices as much as understanding the subject so I think that built up my foundation of Chemistry and that is what made me feel confident about myself when I was doing the O-Level examinations.”

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Bryan Ong

Zhong Hua Secondary School, A1 for O-Level Pure Chemistry

How is the workshop conducted?

  • Designed into workshops with a focused topic(s) coverage, including key essential concepts, application strategies, relationship linkage, easy-to-remember analogies for understanding abstracts.
  • Our lessons are delivered in an interactive manner: participants are encouraged to take part in questioning and answering in every workshop. This ensures your child learns effectively within the shortest period of time.
O-Level Chemistry students clarifying doubts with Mr Sean Chua

I’m interested, how can I register?

Please call us at 98287357 for more details.

“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.”

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Father of Cher Yi Jia

Nan Hua High School, D7 to A2 in 4 months! 

Who is the teacher?

Hi, I am Sean Chua, Chemistry Specialist for O & A – Levels in Winners Education.

  • Being a full-time professional also means 100% dedication, commitment and responsibility to help your child to unlock his true potential to excel in his Chemistry.
  • Because of my years of experience and expertise, I have been interviewed by the media such as The Straits Times, My Paper, Today and Shin Min Daily papers to provide my opinions and views on education topics. In addition, we have been contributing articles quarterly in Popular bookstore member’s magazines since 2012 to share our experience on examination preparation tips, studying techniques and changes to Singapore’s education landscape.
  • Many students and parents know me as the invited author for major books publishers in Singapore and I have written more than five titles of guidebooks, assessment books and Cambridge Ten Year Series (TYS). Most of my Chemistry books are adopted by secondary schools and junior colleges as compulsory or supplementary materials.
  • My academic website, SimpleChemConcepts.com, has been ranked Number 1 on Google for ‘O Level Chemistry tips’ since 2008. In addition, my collection of over 30 Youtube videos has been widely received by local and international students, parents and teachers. Your child will also be able to benefit from the clear, easy-to-understand and concise explanations, just like thousands of our website and video subscribers.

When parents don’t see improvements in their child’s results despite numerous tuitions, when parents see their child struggling with their Chemistry, when parents understand the importance of seeking professional help to assist their child to improve their confidence and results in Chemistry during the critical O-Level or IP Year 4 period,

I am privileged to be the one they turn to for reliability and effectiveness.

They trust my professionalism in always putting their child’s interest as my utmost priority!

Mrs Sim Testimonial of Winners Education. 4 of her children have been attending our O-Level and A-Level classes since 2016

O-Level Chemistry: Simple Electric Cells

In Electrolytic Cells, electricity is used to produce chemical changes. As such, we say that electrical energy is being converted into chemical energy.

The reverse occurs in Simple Cells (also commonly known as Electric Cells) whereby chemical changes is used to produce electricity i.e. chemical energy is being converted into electrical energy.

Parts of Simple Cells:

A simple cell consists of two solid electrodes placed in an electrolyte connected together by an electrical conductor such as wire.

The two electrodes must be two different metals.

The electrolyte can be acid solution, alkaline solution, salt solution or even a fruit such as orange or lemon.

The voltage produced depends on the positions of the two metals in the reactivity series. The further away the metals are in the reactivity series, the larger will be the voltage.

For example, magnesium/copper electrodes pair will give a larger voltage than zinc/copper electrodes pair.

How does Simple Cells Work?

Let’s use an example of a simple cell to discuss further.

  • Metal electrode 1: Zinc
  • Metal electrode 2: Copper
  • Electrolyte: Dilute NaCl
O-Level Pure Chemistry Tuition class questions, IP Chemistry Electrolysis Dilute NaCl

The metal which is higher up in the metals reactivity series will be preferentially oxidised. It will release electrons more readily and is the negative electrode (known as Anode). In the above example, zinc is more reactive than copper, thus zinc electrode will be the negative electrode.

The electrons leave the zinc electrode and pass through the connecting wires to the copper electrode.

The metal lower down in the metals reactivity series will become the positive electrode (known as Cathode). As such, copper will be the positive electrode. The electrolyte contains positive ions (sodium cations) and hydrogen ions. Hydrogen ions has a higher ease of discharge as compared to sodium ions and will be preferentially discharged (reduced) by accepting electrons from the negative electrode via the wire.

This a a redox reactions whereby oxidation and reduction reactions occurs simultaneously. Electrons is being transferred from zinc atoms to hydrogen ions.

Uses of Simple Cells:

Simple Cells are commonly also known as batteries which provides a portable form of electrical energy. They supply electricity to watches, torches, etc which do not have to connected to the main electricity supply.

YouTube Video Tutorial on Simple cells in Electrolysis

You can watch the YouTube Video below to have an even clearer idea about Simple Cells.

Length of Video: 11.02 minutes

Direct Video Link: https://www.youtube.com/watch?v=MAwJ2wiIBzo

Do understand the difference between Simple Cells and Electrolytic Cells. Every year, I have a large number of students in my O-Level Chemistry Tuition Class and IP Chemistry Tuition Class who told me that they are confused by their school Chemistry teachers and Chemistry tutors with regards to how the two types of cells work. If you have not read my blog posts regarding Electrolytic Cells, you should do a search for them using the search box at the top right hand corner.

I hope you find the content easy for your understanding and that this article will be part of your Chemistry Notes to master Electrolysis topic.

If you have anything valuable to add, leave me a comment below. 

Feel free to share this blog post with your friends.

Subscribe to my blog to receive 2 updates per month sent to your email!

If you are based in Singapore and needs help with Sec 3 or Sec 4 Chemistry concepts, you can join my weekly O-Level Pure Chemistry and IP Chemistry Tuition Classes.

5 Effective Ways to Prepare for O Level Pure Chemistry and IP Chemistry Even If Your Child Has Been Failing Their Exams

Many parents often asked us: “Is there still time for my child to do well in O Level or IP?” Every June holidays, we receive many phone calls from anxious parents seeking help for their children who didn’t performed well for their mid-year examinations.

We understand their concern. After all, it’s just 4 months before their child sits for the national examination, GCE O Level or their IP examination. Doing well for the O-Level or IP examination gives their child more options to choose from for schools and courses to further their education.

From now till the O Levels, students must stay focused and adopt the correct strategies so as to prepare themselves confidently for the examination. For Chemistry, we suggest the following:

1. Build up Strong Foundation of Basic Concepts

Based on our decades of teaching experience, the root problem we noticed in students underperforming in examination is their lack of understanding of the fundamentals in Chemistry. The level of understanding in the basic concepts is way below par.

Building a strong foundation is the key when students prepare for the O Level Pure Chemistry or IP Chemistry examination, following a topic-by-topic approach. For each topic, students must revise and understand the underlying key concepts or formula, before moving to the next topic.

In Chemistry, it is important to know and master the topics taught in Secondary 3 first. For example, students must have very clear understanding of Secondary 3 basic essential topics such as Chemical Bonding, Writing Balanced Chemical & Ionic Equations, Acids & Bases as well as Mole Calculations. Chemistry is a much more abstract science subject compared to Physics and Biology because almost every topic is interrelated to another topic, especially those covered earlier in Secondary 3.

2. Pay Attention to the Usage of Keywords in Structured Questions

How many of you have your children telling you that they really pay attention in class and can understand what their teachers are teaching?

However, their examination results are dismay and they do not understand why.

This is because just knowing the key concepts i.e. “stories” is not sufficient.They will be marked by the examiners based on the correct keywords or key phrases written.

One of the main challenges that many Chemistry students faced is answering structured questions with the appropriate, specific, complete set of keywords.

For example, the correct keyword for a question could be “Graphite conducts electricity due to mobile electrons” but the common mistake that many students made is “Graphite conducts electricity due to mobile ions”. The reason for such mistake is often rote memorisation without truly understanding the structural properties of graphite and in examination they tend to write the wrong keywords. A-Grade students are able to write the correct keywords as they have their basic concepts to back up their choice of keywords.

Mastery of Chemistry involves strong foundation of basic concepts coupled with clear usage of keywords on top of their application skills.

3. Attempt Ten-Years Series Questions

Next, to put their understanding of each topic to the test, students are advised to start work immediately on the O Level questions as it will provide a reasonable gauge for their level of understanding on key concepts, their level of application skills and build up their confidence at the same time.

Since strong foundation is built on a topic-by-topic approach, the use of the Ten-Years Series (TYS) topical books is strongly recommended, preferably one that provides step-by-step detailed solutions. This allows students to check on the answers at their own convenience.

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Do you know A-grade students ask a lot more questions? They think more and do not simply just accept what is taught.

4. Keep Clarifying

Building a strong foundation consists of understanding the key concepts for each topic, testing the student’s understanding by working on the questions, and most importantly, clarifying any doubts and correcting any mistakes made.

Many students accumulate so many doubts over the years that it has reached a critical stage that these doubts, if remained unresolved will cripple their chance of performing well in the
O Level or IP examinations. They must start asking questions to clear their doubts in order to feel confident and prepared!

If your child is afraid of embarrassment, get him to ask someone who has the most up-to-date knowledge in Chemistry concepts and someone he is comfortable with, for example, his friends, his siblings, his teachers or tutors. With technology, he can even email or message his questions to someone he trusts.

Some TYS books even highlight mistakes that are commonly made, and this feature helps students learn how to avoid them during the examination.

5. Examination Strategies

“Know thy self, know thy enemy. A thousand battles, a thousand victories.” – Sun Tzu, The Art of War

Taking examination is just like a game. Your child plays to win within a given time frame, and to win this game, your child must be prepared and aware of the rules of the game. The real opponent is himself.

Once your child has mastered all the key concepts for all the topics, the next step is to learn how to manage his time during the examination. He can attempt a full set of examination papers, under timed condition, to simulate the actual O Level examination. In fact, we put our students through such timed trial exercises in our weekly teachings so that they can understand and appreciate the importance of time management during examination. Through these timed exercises, they can also gain more exposure to a wide variety of questions which will future enhance and challenge their understanding.

I hope you find the content easy for your understanding and if you have anything valuable to add, leave me a comment below. Feel free to share this blog post with your friends.

Subscribe to my blog to receive 2 updates per month sent to your email!

O-Level & IP Pure Chemistry: Hydrogen-Oxygen Fuel Cell


Just read an article in The Straits Times local newspapers on Hydrogen-Oxygen Fuel Cell few days back and it gave me an idea to blog about it. Huge potential to be a Chemistry question in your upcoming GCE O-Level Pure Chemistry or IP Chemistry examinations. I have always been reminding students in our Sec 4 O-Level and IP Chemistry Tuition Classes in Singapore on the importance of fuel cell and today i would like to share with you also.

Combustion of Fuels

First of all, let’s take a look at the primary source of energy which is fuels, which are substances that can burn easily in air to give out energy. The most common used fuels are fossil fuels (coal, petroleum and natural gas) which are formed from decayed plants and animals that lived millions of years ago. They are being covered more in the topic of Organic Chemistry. Other types of fuels being used are wood and hydrogen.

When fuels burn, combustion reaction between the fuel and oxygen in the air occurs. All combustion reactions are exothermic in nature and heat energy is given out to the surroundings.

Fuel Cells

Combustion reactions are only one way to extract useful energy from the fuels. Scientists have long ago explored ways to convert chemical energy of fuels directly to electrical energy (i.e. does not require combustion reaction).

This is known as a fuel cell which is a chemical cell in which reactants (usually a fuel and oxygen) are continuously supplied to produce electricity directly.

There are many types of fuel cell but the hydrogen-oxygen fuel cell is the best known example. It has been used as a source of electrical energy in space vehicles.

Hydrogen and oxygen gases are continuously pumped and supplied into the chemical cell.

At the positive electrode (known as the cathode), oxygen is reduced to form hydroxide ions.

O2(g) + 2H2O(l) + 4e– → 4OH–(aq)

At the negative electrode (known as the anode), hydrogen is oxidised to form water.

2H2(g) + 4OH–(aq) → 4H2O(l) + 4e–

Combining the two half equations above shows that hydrogen and oxygen are converted into water. The reaction equation is the same as that for the combustion of hydrogen.

2H2(g) + O2(g) → 2H2O(l)

Fuel cells produce electricity indefinitely provided there is a continuous supply of fuel. This is unlike ordinary chemical cell (battery) which will be used up.

So what are the advantages of using hydrogen-oxygen fuel cell? Seems like hydrogen can be used as an alternative to fossil fuels which are rapidly declining because the demand for them has increases exponentially.

Advantages of using Hydrogen-Oxygen Fuel Cell:

  1. It does not cause pollution since only water is produced.
  2. Hydrogen is considered a renewable source of energy since it can be obtained from the electrolysis of water.
  3. Fuel cells have a higher efficiency than diesel or gas engines. Less energy is lost to surrounding as compared to combustion.

But, how come fuel cells are not commonly used? Is there any limitations in using hydrogen-oxygen fuel cells as a source of energy?

Disadvantages of using Hydrogen-Oxygen Fuel Cell:

  1. No cheap sources of hydrogen. Obtaining hydrogen from electrolysis is an expensive process. Currently, hydrogen is obtained from non-renewable energy sources such as cracking of petroleum.
  2. Hydrogen is extremely flammable and explosive. As such, special precautions must be considered when it comes to storage and transportation of hydrogen.
  3. Hydrogen is also very light (relative molecular mass of 2) and requires a larger storage volume as compared to other fuels. There is currently no effective way to store hydrogen.

Hydrogen-oxygen fuel cell has huge potential to be the main source of energy but at the moment, the technology is not well developed and the cost of using hydrogen-oxygen fuel cell is high. Main use is still in space vehicles. Developed countries are trying to implement hydrogen-oxygen fuel cells in vehicles. Singapore is one of them.

I hope you find the content easy for your understanding and if you have anything valuable to add, leave me a comment below.

Feel free to share this blog post with your friends.

Subscribe to my blog to receive 2 updates per month sent to your email!

PS: For students based in Singapore taking the Pure Chemistry or IP Chemistry syllabus, do note that Fuel Cell is listed in the topic of Energy Changes and not the topic on Electrolysis. This applies to the Pure Chemistry textbooks titles by both Marshall Cavendish and Pearson publishers, which are approved by Ministry of Education (MOE).

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

O Level and IP Chemistry Tuition Singapore

2018 O-Level Pure Chemistry MCQ Paper 1 Answers (Subject code: 6092)

1.     B
2.     B
3.     C
4.     D
5.     A
6.     A
7.     B
8.     C
9.     D
10.  B
11.  C
12.  C
13.  B
14.  B
15.  A
16.  D
17.  C
18.  D
19.  B
20.  A
21.  B
22.  A
23.  A
24.  A
25.  D
26.  B
27.  D
28.  D
29.  A
30.  D
31.  C
32.  D
33.  A
34.  D
35.  B
36.  B
37.  D
38.  C
39.  C
40.  C

Join us in 2019 Score 100% O-Level Pure Chemistry MCQ Workshop! Talk to us at 9828 7357 for early bird registration (Jan to July 2019)

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2018 Score 100% O-Level Pure Chemistry MCQ Workshop (10th Year)