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Published by
World Scientific Publishing Co. Pte. Ltd.
5 Toh Tuck Link, Singapore 596224
USA office: 27 Warren Street, Suite 401-402, Hackensack, NJ 07601
UK office: 57 Shelton Street, Covent Garden, London WC2H 9HE

Library of Congress Cataloging-in-Publication Data
Names: Nan, Zhihan, author. | Zhang, Sheng (Lecturer in chemistry), author.
Title: Theory and problems for Chemistry Olympiad : challenging concepts in chemistry /
Zhihan Nan, Sheng Zhang.
Description: New Jersey : World Scientific, [2020] | Includes index.
Identifiers: LCCN 2019030146 | ISBN 9789813238992 (hardcover) |
ISBN 9789811210419 (paperback)

Subjects: LCSH: International Chemistry Olympiad--Study guides. |
Chemistry--Problems, exercises, etc.
Classification: LCC QD42 .N32 2019 | DDC 540.76--dc23
LC record available at />
British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library.

Copyright © 2020 by World Scientific Publishing Co. Pte. Ltd.
All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means,
electronic or mechanical, including photocopying, recording or any information storage and retrieval
system now known or to be invented, without written permission from the publisher.

For photocopying of material in this volume, please pay a copying fee through the Copyright Clearance
Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. In this case permission to photocopy
is not required from the publisher.

For any available supplementary material, please visit
/>Typeset by Stallion Press
Email:
Printed in Singapore

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CONTENTS

Foreword by Professor Richard Wongvii
Attributionsix

1. Introduction and General Tips to Prepare for Chemistry Olympiad

1

2. Physical Chemistry

5



2.1.Thermodynamics

6



2.2. Chemical Equilibria

39



2.3. Thermodynamics of Phase Transitions

61



2.4. Thermodynamics of Mixtures


70



2.5.Electrochemistry

90



2.6. Reaction Kinetics

101

3. Inorganic Chemistry

121



3.1. Atomic Structure and Quantum Theory

122



3.2.Periodicity

134




3.3. Chemical Bonding

137



3.4. Acid-Base Chemistry

149



3.5. Main Group Chemistry

153



3.6. Crystal Structure

184



3.7. Coordination Chemistry

197


4. Organic Chemistry

225



4.1. Introduction to Organic Chemistry

226



4.2. Optical Activity and Stereochemistry

236



4.3. Conjugation and Aromaticity

245

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vi   Theory and Problems for Chemistry Olympiad




4.4.Acidity, Basicity, Nucleophilicity and Electrophilicity of
Organic Compounds

252



4.5. Radical Chemistry

263



4.6. Nucleophilic Addition

277



4.7. Nucleophilic Substitution

289



4.8. Elimination Reactions

314




4.9. Electrophilic Addition

326



4.10. Electrophilic Substitution

336



4.11. Enolate Chemistry

350



4.12. Oxidation and Reduction

368



4.13. Protecting Groups in Organic Chemistry

381




4.14. Pericyclic Reactions

386



4.15. Organometallic Chemistry

400



4.16. Retrosynthetic Analysis

408

5. Practical Techniques

416



5.1.Titration

417




5.2. Techniques in Organic Synthesis

425



5.3. Qualitative Analysis

430

6. Sample Problems and Solutions

444



6.1. Sample Problem Set

447



6.2. Solutions to the Sample Problems

464

Index

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539

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FOREWORD

The International Chemistry Olympiad (IChO) celebrated its 50 th anniversary in
2018, growing from a small competition with only 3 participating countries and 18
competing students to what it is now — a worldwide event attracting 76 countries
and 300 students. To select a team of students to represent Singapore at IChO, the
Singapore Chemistry Olympiad (SChO) was launched in 1989 and it has become an
annual event since then.
Chemistry Olympiad aims to motivate pre-tertiary students to study beyond
the syllabus and stimulate their thinking through solving challenging chemistry
problems. It is able to further develop the interest of pre-tertiary students in chemistry and improve chemistry education by providing interested students with more
resources.
This book is the first textbook that caters specifically to students preparing for
the Chemistry Olympiad competition. Previously, eager students had to browse
through many university level textbooks to gain bits and pieces of information in the
different fields of chemistry. The objective of this book is to bring down university
level concepts to pre-tertiary students in a concise manner, combining important
knowledge from all fields of chemistry into one book. The book presents chemical
concepts in a succinct fashion, with key focus on the logical flow of concepts. Clear
explanations are given such that students are able to fully understand the theories
presented.
As I read through the draft of “Theories and Problems for Chemistry Olympiad”,
I was impressed by how the concepts taught in university are linked to the topics
familiar to pre-tertiary students. The knowledge gap was bridged through detailed
justification, with every physical chemistry equation derived and every organic

reaction described by its mechanism. It was a joy to read through as there were
many figures and diagrams used to illustrate the concepts. The writing is clear and
easy to read, so it should help even a beginner get his/her bearing. In particular, the
pedagogy is effective in keeping readers engaged as each chapter connects to the
next. At the end of the book, students are also able to test their understanding by
attempting sample IChO problems with detailed solutions.

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viii   Theory and Problems for Chemistry Olympiad

Nan Zhihan has participated in IChO 2016, achieving a gold medal and the
IUPAC prize for highest score in the experimental examination. After participating
in the competition, he has devoted much of his efforts in mentoring and training
the Singapore team for IChO 2017, 2018 and 2019. As a gold medallist, he
understands the requirements and challenges in preparing for the competition
and shares his personal experience in this book. Dr Zhang Sheng is a lecturer at
the Department of Chemistry, NUS, and has been the mentor of the Singapore
Chemistry Olympiad team for 9 years, training and leading the Singapore team for
International Chemistry Olympiad competitions. Over the years of his mentorship,
Singapore team has won a total of 16 Gold Medals and 19 Silver Medals in IChO.
With vast experience in Chemistry Olympiad training, Nan Zhihan and Zhang Sheng
form a formidable team to complete this valuable resource for perspective students.
I believe that this book is a valuable companion for students preparing for the
Chemistry Olympiad competition. However, I would also recommend this book to
any student curious to learn more about chemistry, including freshmen at university.
With Chemistry Olympiad gaining prominence, I encourage interested students to

take up the challenge and discover their passion in chemistry.
Professor Wong Ming Wah, Richard
Head, Department of Chemistry
National University of Singapore

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ATTRIBUTIONS

Chapter 2.5
Figure 2.5.4:  Sample galvanic cell by Hazmat2 is from Wikipedia commons.
Chapter 3.1
Figures 3.1.2 to 3.1.4 and 3.1.6: Orbital Graphs by As6673 are from Wikipedia
commons, licensed under CC BY-SA 3.0.
Chapter 3.6
Figure 3.6.2:  Monoclinic cell by Fred the Oyster from Wikipedia commons, licensed
under CC BY-SA 3.0. Modified to describe the 7 crystal systems.
Figure 3.6.3:  Primitive cubic unit cell by DaniFeri from Wikipedia commons, licensed
under CC BY-SA 3.0.
Figure 3.6.4 and Figure 3.6.7: Body-centred cubic unit cell by Chris He from
Wiki­pedia commons, licensed under CC BY-SA 4.0. Each figure has been modified
to show only 1 unit cell. Atom labels are added for CsCl unit cell.
Figure 3.6.5: Face-centred cubic unit cell by Christophe Dang Ngoc Chan from
Wikipedia commons, licensed under CC BY-SA 3.0. Modified to show only 1 unit
cell.
Figure 3.6.6:  NaCl lattice by Prolineserver from Wikipedia commons, licensed under
CC BY-SA 3.0. Atom labels were added to the lattice.

Figure 3.6.8 and Figure 3.6.9:  Fluorite and Zinc Blende crystal structure by Tem5psu
from Wikipedia commons, licensed under CC BY-SA 4.0. Each figure has been
modified to show only 1 unit cell. Atoms are labelled for both crystal structures.
Figure 3.6.11:  Spinel unit cell by Andif1 from Wikipedia commons, licensed under
CC BY-SA 4.0. Atoms are labelled on the figure.
Figures 3.6.12 to 3.6.14:  Figures for the types of crystal defects by VladVB from
Wikipedia commons, licensed under CC BY-SA 3.0.

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1. INTRODUCTION AND
GENERAL TIPS TO
PREPARE FOR
CHEMISTRY OLYMPIAD
Welcome to Chemistry Olympiad! Chemistry
Olympiad is a challenging competition that
tests students on their higher-order thinking
ability and encourages interested high school
students to read up beyond the syllabus. This
book was written to explain tough university

chemistry concepts to high school students,
by building up the student’s knowledge slowly
starting from the basics. When reading this
book, please appreciate the logical flow of
concepts and find the links between different
topics. With time, I hope that you will see the
beauty in chemistry, and have an enriching
journey through Chemistry Olympiad.

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2   Theory and Problems for Chemistry Olympiad

As the flow of chapters and content in this book is meticulously designed, I would
urge you to read the book following the order of the chapters and sub-chapters. This
will ensure that you have the proper background knowledge required to understand
every chapter fully. After completing the book once, it can be used as a reference
book to refresh yourself on the relevant topics once in a while.
As a tip, it will be good to keep a notebook to write down important concepts
and equations while reading the book. From the derivations of equations in physical
chemistry to the mechanisms in organic chemistry, it is important to try these on
your own to fully understand the concepts. While looking at complicated reactions
or concepts, keep questioning in your head why each step proceeds the way it does.
Note down any questions you have and ask your supervisor. While the learning curve
is definitely steep, I am sure that the rewards are worth every bit of time and effort.
The journey through Chemistry Olympiad is most rewarding when you are driven
by your interest in chemistry and curiosity to learn more, instead of just going for a

medal in the competition.
In Chemistry Olympiad, the competition is the final challenge to test your ability.
In most countries, there are various national Olympiad competitions to select students for the International Chemistry Olympiad (IChO), the dream for most aspiring
Chemistry Olympians. After all the hard work that is put into learning chemistry, it
is critical to perform to the best of your ability at the competition. Here, the authors
list some tips from experience to help students do their best at the competition.
For any competition, stress and mood through the examination play a significant role in how well we can think. When years of hard work culminate in a
5-hour long examination, it is difficult to not be overwhelmed by stress. Thus, you
should face every competition with excitement, thinking of the competition as a
new opportunity to learn more chemistry through problem-solving. Even if you
are unsure of the solution to certain problems, do not let it discourage you, as
the Olympiad competition is designed to be challenging. In the end, it is not the
results that matter the most, but that you have given your best effort through the
journey of learning chemistry.
Upon starting the paper, browse through all the questions first. Generally,
Olympiad questions are not ranked by difficulty level. In particular, while one student
may find an organic chemistry question more challenging, another student may
have a difficult time solving a physical chemistry question. In the Olympiad competition, many students will find themselves having insufficient time to complete all
the questions. Thus, find the questions that you are most confident in solving, and
ensure that they are completed correctly and efficiently before attempting the more
challenging problems.
For some common constants, you should use the value that is given in the
“Constants and Formulae” table in front of the paper, regardless whether the value
is the same or different compared to the value you have memorised. For example, the

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Introduction and General Tips to Prepare for Chemistry Olympiad   3

speed of light is given as c = 3.000 × 108 m ⋅ s-1 (IChO 2011) and c = 2.998 × 108 m ⋅ s-1
(IChO 2018). You should also use the atomic mass from the Periodic Table given in
the question paper. For example, the mass of a hydrogen atom was given as 1.01
(IChO 2010), 1.008 (IChO 2011) and 1.00794 (IChO 2015).
For physical chemistry questions, it is important to show full workings on how the
answer was obtained. Sometimes, there might be small errors during the calculation
that lead to a different answer. If the final answer is incorrect, points may be awarded
for correct equations in the working. To avoid losing all the points due to a small careless error, please show all key steps leading to the final answer. This also helps when
checking the answer again for any errors. While working through physical chemistry
problems, it is recommended to leave your answers in symbolic form while working
through the problem. This makes it easier to spot any algebraic errors, and minimise
the time spent on pressing the calculator. If any intermediate value is obtained, try
to leave it to 1 or 2 more significant figures than the final required answer. You do
not need to copy down all the decimal places from your calculator, because that’s
just a waste of your time and it will not affect your final results.
As per all scientific calculations, standard rules for decimal places and significant
figures apply in Chemistry Olympiad calculation. If a question requires students to
report the results to a certain number of significant figures, such requirement should
be stated clearly in the question. If a question has not stated such a requirement, then
you just need to report your value with a reasonable number of significant figures.
For example, a concentration of 0.1028 mol ⋅ dm -3 or 0.103 mol ⋅ dm -3 is reasonable,
but 0.102774125 mol ⋅ dm -3 is obviously not reasonable although that’s the value
shown on the calculator.
For inorganic chemistry, it is important to be familiar with the properties of
different elements and ions, such as the colour of transition metal cations in their
various oxidation states, the flame test results of cations, common oxidation states
of elements, solubility of common inorganic salts and colour of common precipitates.
This information will often give intuition into the identity of unknown compounds

in inorganic elucidation questions. While a summary is provided in the qualitative
analysis Table 5.1, I would still encourage students to test out reactions and make
the observations themselves.
You should also memorise the atomic mass of common elements, as this will
allow you to easily access molecular masses of common compounds. This may be
useful to deduce the identity of inorganic compounds in calculation-type questions.
For example, a molecular mass of 18 suggests H2O, 28 suggests CO, and 44 suggests
CO2 . Now, try the following for yourself: 98, 100, 160. Of course, there are still many
others. You should try to summarise your own table of common molecules and their
molecular masses.
Other than deducing compound identity through calculations, it is also possible
to make good judgements based on periodicity and the trends within each group.

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4   Theory and Problems for Chemistry Olympiad

Thus, it is good to have a brief understanding of the elemental trends in each group,
as outlined in chapter 3.5.
For organic chemistry, it is useful to work on structural elucidation both forwards
and backwards. The process of visualising a synthesis backwards is known as retro­
synthesis, and is briefly discussed in chapter 4.16. You can compare the reactant and
product to determine the parts of the molecule with no change. After identifying the
parts that do not change in the reaction, it is possible to focus on the reactive site(s).
This allows us to deduce the reaction mechanism, which may be single or multi-step.
From time to time, you will encounter some organic reagents that you have not
met before. Based on structural features, it is possible to compare such reagents with

familiar reagents to deduce its role, as solvent, catalyst, acid, base, oxidant, reductant,
nucleophile or electrophile. Once its role is confirmed, it is possible to determine the
reaction mechanism and predict the product.
When analysing reactions, pay special attention to selectivity, including chemoselectivity, regioselectivity and stereoselectivity. In particular, stereoselectivity is often
encountered in Chemistry Olympiad. Sometimes, stereochemistry can be deduced
either from the reactant one or several steps before, or from the product one or
several steps after. Also, you should decide whether there is a retention or inversion
of stereochemistry based on the reaction mechanism. In general, stereochemistry
should be shown clearly with wedged or dotted lines.
The tips provided here in this chapter are general and more specific tips regarding
each topic will be given as you move on into the book. I wish all students an enriching
and rewarding Chemistry Olympiad journey!

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