UK Chemistry Olympiad

By Alex Throw (AThrow#4505)

Introduction

The UK Chemistry Olympiad has run annually since 1983. It is a competition designed not only for the purpose of selecting four young chemists to represent the UK at the International Chemistry Olympiad (IChO) in the summer, but also for students to enjoy participating in competitive chemistry. It consists of two rounds before the IChO team is selected.

Round 1

Eligible Students and Participation

All students in secondary schools and colleges in the British Isles are eligible to participate in round 1. Please note that if you will be over 19 by the time of the IChO in late July, you will not be allowed to progress through to round 2. A teacher from your school should sign you up online if you wish to participate. If your school does not usually enter, then talk to your chemistry teacher in the autumn before the competition. The exam is organised and supervised by your school. A growing number of people participate every year, and in 2020, there were 9182 participants.

Dates

In late January, the round 1 exam is held. It consists of a single, 2-hour theoretical exam. The paper is then marked over the next week or so by your chemistry teachers and the highest scoring scripts are sent off for moderation. You should receive your mark at some point in February. The grade boundaries are usually released in late February or early March, along with the invitations to round 2.

Awards

Gold, silver, and bronze awards are awarded to a predetermined percentage of participants based on their score, so the grade boundaries change each year as the difficulty of the paper changes. In 2020, 8% of students received gold awards, 24% of students received silver awards, 36% of students received bronze awards, and the rest received commendations.

A group of 25-30 students is also selected each year to participate in round 2 of the competition, and the boundary for entry into round 2 varies greatly depending on the difficulty of the paper. For example, in 2020 this boundary was about 80% and in 2019 it was about 60%.

Structure of the Paper

The round 1 paper consists of 5 or 6 questions with multiple parts. The question type varies greatly, from a few multiple-choice questions to calculations to determining organic structures. The questions cover a wide range of topics and often have quirky themes for the enjoyment of the students. Each answer is usually worth 1 or 2 marks, with some of the longer calculations sometimes being worth 3 marks. The total number of marks available has changed over the years but seems to have settled recently in the mid-80s.

No aids are allowed in the exam, but a periodic table and some useful constants and formulae will be given in the question paper. The values for constants and atomic masses given should always be used over memorised or calculator values.

Content of the Paper

The papers cover most of the key concepts of A-level Chemistry, and these concepts should be common to all exam boards. These topics include, but are not limited to:

• Writing chemical equations
• Moles (e.g., percentage yield, titration calculations)
• Thermodynamics (e.g., Hess cycles, enthalpy/entropy change of reaction)
• Shape and structure (e.g., VSEPR, dot and cross diagrams)
• Organic reactions (e.g., LiAlH4 reduction, SOCl2 chlorination, aromatic substitution)
• Basic spectroscopy (e.g., mass spectroscopy, infrared, NMR)
• Kinetics (e.g., rate laws, graphs)
• Redox chemistry (e.g., redox reactions, common half-cell equations)
• Electrochemistry (e.g., cell potentials)
• Crystal structures (e.g., unit cells)

Often, the paper introduces a new concept that you are not expected to have studied beforehand. A brief explanation will be given before questions on the topic. These questions can all be answered with the information given, but they are often quite challenging and test the student's ability to pick up new concepts quickly.

In addition, there are usually some questions involving unfamiliar chemistry with no explanation - for example a reaction in an organic synthesis that is not on the A-level syllabus. However, it should be possible to deduce the correct answer using all the information given, and by applying concepts you already know to a new situation.

Preparation

When preparing, the first thing that should be done is to make sure you have a thorough knowledge of all the A-level content. Sections of the A-level regarding applications of certain chemical processes and conditions of reactions can be left out, as these differ between exam boards. For example, it is not necessary to know about catalytic converters as an example of transition metal catalysis, even though it appears on some A-level specifications.

While the A-level course is certainly enough for a gold award, a higher-level textbook may be necessary to advance to Round 2. A good place to start is Chemical Structure and Reactivity by Wothers. This should only be done if you are very confident with the A-level content, as it will not help with most of the paper but can simply push an already high mark to an even higher one.

The best preparation is past papers. Papers from 2003 can be found online with mark schemes. Make sure you leave enough time to get through as many as you can - but don't do them all too early! If you only have time to do a few, it is best to do the papers from recent years as the question style and overall paper difficulty has changed over time. Make sure you do the past papers under timed conditions to get used to the time pressure. Focus on mistakes and work to improve any weak spots. Do not fall into the trap of thinking “I would have got that in the real thing” and moving on. By carefully going through past papers in this way, you should get used to the style and difficulty of the questions.

Advice on Taking the Paper

Taking the paper can be stressful and this can hinder students' performances. If you are stuck on a question, the best thing to do is move on as there may be questions later in the paper that you can answer. Also, not all the parts of a question are linked and even if you can't do one part of a question, you may be able to answer a later part. Make sure you read all questions carefully and look at all the information and hints given as they are usually there for a reason. Do not over complicate simple questions as it should be possible to answer them using A-level knowledge alone.

It is a difficult paper and usually no one gets everything right. So, don't worry if you don't know how to do a question - it would be extraordinary if you could answer them all!

Round 2

Dates

Round 2 takes place in late March over a long weekend, and the final team of 4 is chosen either at the end of the long weekend or by early April.

Weekend Timetable

Note that what follows is how round 2 was done pre-COVID and may change in future years. In 2020, round 2 consisted solely of two online lectures and a remote 4-hour theoretical exam.

Usually, this round is held over 4 days, from Thursday to Sunday in the chosen week at The University of Cambridge. On Thursday afternoon, students arrive and meet the other participants and the members of the Olympiad Working Group (which includes organisers and mentors of the IChO team). On Friday, morning laboratory demonstrations in an undergraduate laboratory cover techniques needed for the practical exam that afternoon. On Saturday, theoretical lectures are given in the morning on advanced topics that will come up in the afternoon theoretical exam. On Sunday morning, the team members are announced, and the students depart.

Practical Exam

The practical exam contributes 40% of the final score for this round. It is usually four hours long and consists of three or four experiments in a similar style to the IChO practical exam. It tests students' ability to do multiple experiments at the same time. Common advanced practical skills, which will have been demonstrated that morning, include:

• Volumetric analysis (e.g., redox titrations, back titrations)
• Observational tests
• TLC techniques
• Organic synthesis
• Recrystallisation
• Biphasic workup
• Reflux
• Distillation

Marks are awarded more for the results of the experiment than the calculations. For example, titrations are marked on how close the final titre used is to the actual value. Organic syntheses are marked on percentage yield and on purity.

Practical Advice and Preparation

In this exam the most important things are organisation and time-management. You should always keep your workspace as tidy as possible. If the workspace is cluttered, it is easy to lose track of equipment and chemicals, making everything a little bit more difficult, which is certainly not helpful in such a stressful exam.

In terms of time-management, it is worth spending 5-10 minutes at the start of the exam reading through each experiment and coming up with a plan of how you will spend your 4 hours. Then you always have an idea of what you are doing when and know that you will be able to finish all the experiments in time if you stick to the plan. When planning, check if any experiments contain long waiting periods, such as a 40-minute reflux in an organic synthesis. These experiments should be set up early, and another experiment can be started when waiting for them to finish.

While the exam is time-pressured, it is better to take your time in the experiments, especially in volumetric analyses and organic syntheses. If you rush through the experiment, there is a much higher chance of losing yield or purity or getting an inaccurate result. Also, if you overshoot a titration or ruin an organic product then you will have lost a large amount of time.

The knowledge required for the practical exam is minimal. It is useful to learn the basic inorganic tests for different cations and anions and their results, as there may be an experiment dedicated to this. Additionally it is worth looking over the theory of some of the experimental techniques such as recrystallisation, as it helps to understand what you are doing.

If you are able to, ask your teacher for time practising certain common techniques, such as using a volumetric pipette and titrating accurately, and even practising methods of organic synthesis such as reflux, distillation, and recrystallisation. However, for many students this is not a possibility. Do not worry if this is the case! As long as you are careful and manage your time well, you will certainly do better than others who have practised their skills but are disorganised. Simply reading about the practical techniques you need should be enough, as they do not expect you to know any complex techniques beforehand.

Theoretical Exam

The theoretical exam counts for 60% of the final score for round 2. It is similar in structure to an IChO paper, with about 8 questions with multiple parts. The difficulty is much higher than round 1, and many students who did very well in round 1 can still find it challenging. The syllabus includes everything from round 1, in addition to extra reading sent to the students before round 2. This extra reading is usually a few chapters from Chemical Structure and Reactivity by Wothers. The advanced topics that were discussed in lectures in the morning will also be tested. Typical advanced topics are:

• Advanced organic synthesis
• Thermodynamics (e.g., second law, temperature dependence of K)
• Kinetics (e.g., integrated rate laws, steady-state approximation)
• Quantum mechanics (e.g., particle in a box, harmonic oscillator)
• Solid state structures
• Electrochemistry

Theoretical Preparation

Students invited to round 2 will be sent a copy of Chemical Structure and Reactivity and asked to read specific chapters before the training weekend. However, if your goal is getting into the top 4, more reading should be done. It is best to read most, if not all of Chemical Structure and Reactivity. In addition, it will be incredibly helpful to read a large number of the early chapters of Organic Chemistry by Clayden (most of the second half of the textbook goes into too much detail even for IChO!).

Unfortunately, the Royal Society of Chemistry does not release round 2 past papers, and so there is no material to practice with. However, due to the similarity of the questions with IChO problems (they have even borrowed parts from past IChOs), have a go at some past IChO problems, either preparatory or final. The round 2 questions will not require the same level of knowledge as these problems, but they will be of a similar style.

Concluding Remarks

The UKChO is a brilliant competition for students with a range of talent in chemistry. It is enjoyable and can be incredibly rewarding. Getting through to round 2 is an exceptional achievement and, who knows, you may even end up flying off to another country to represent the UK at the IChO. Good luck!

UKChO Website: https://edu.rsc.org/enrichment/uk-chemistry-olympiad