IChO 2009, Експеримент — Задача 3. Practical problem3 — The Critical Micelle Concentration of a Surfactant

The Competition Problems from the International Chemistry Olympiads, Volume3,41st–45th IChO2009–2013. Edited by Anton Sirota. IUVENTA–Slovak Youth Institute, Bratislava2014. This scoped paper preserves only the41st International Chemistry Olympiad,18–27July2009, Cambridge, United Kingdom.

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Copyright2014IUVENTA–IChO International Information Centre; ISBN978-80-8072-154-1. Attribution: The Competition Problems from the International Chemistry Olympiads, Volume3, edited by Anton Sirota, Bratislava2014.

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Issued by IUVENTA – Slovak Youth Institute in 2014 with the financial support of the Ministry of Education of the Slovak Republic. Number of copies: 250. Not for sale.

International Chemistry Olympiad, International Information Centre, IUVENTA – Slovak Youth Institute, Búdková 2, SK 811 04 Bratislava 1, Slovakia. E-mail: anton.sirota@stuba.sk. Web: www.icho.sk.

Preface This publication contains 39 theoretical and 14 practical competition problems from the 41st – 45th International Chemistry Olympiads (IChO) organized in the years 2009 – 2013. It has been published by the IChO International Information Centre in Bratislava (Slovakia) as a continuation of the preceding Volumes 1 and 2 published on the occasion of the 40th anniversary of the IChO with the titles: • The competition problems from the International Chemistry Olympiads, Volume 1, 1st – 20th IChO, 1968 – 1988 (IUVENTA, Bratislava, 2008). • The competition problems from the International Chemistry Olympiads, Volume 2, 21st – 40th IChO, 1989 – 2008 (IUVENTA, Bratislava, 2009). Not less than 318 theoretical and 110 practical problems were set in the IChO during the forty-five years of its existence. In the elaboration of this collection the editor had to face certain difficulties because the aim was not only to make use of past recordings but also to give them such a form that they may be used in practice and further chemical education. Consequently, it was necessary to make some corrections in order to unify the form of the problems (numbering the tasks of the particular problems, solution inserted immediately after the text of the problem, solutions without grading points and special graphs used for grading of practical problems). Nevertheless, the mentioned corrections and changes do not concern the contents and language of the competition problems. The practical problems set in the IChO competitions, contain as a rule some instructions, list of apparatuses available, chemicals on each desk and those available in the laboratory, and the risk and safety phrases with regard to the chemicals used. All of these items are important for the competitors during the competition but less important for those who are going to read the competition tasks of this collection and thus, they are omitted. Some parts of the solutions of practical problems are also left out since they require the experimental data which could be obtained by experiments during the practical part of the IChO competition. In this publication SI quantities and units are preferred. Only some exceptions have been made when, in an effort to preserve the original text, the quantities and units have been used that are not SI. Although the numbers of significant figures in the results of some solutions do not obey the criteria generally accepted, they were left without change.

Unfortunately, the authors of the particular competition problems are not known and due to the procedure of creation of the IChO competition problems, it is impossible to assign any author's name to a particular problem. Nevertheless, responsibility for the scientific content and language of the problems lies exclusively with the organizers of the particular International Chemistry Olympiads. This review of the competition problems from the 41st – 45th IChO should serve to both competitors and their teachers as a source of further ideas in their preparation for this difficult competition. For those who have taken part in some of these International Chemistry Olympiads the collection of the problems could be of help as archival and documentary material. In the previous forty-five years many known and unknown people - teachers, authors, pupils, and organizers proved their abilities and knowledge and contributed to the success of this already well known and world-wide competition. We wish to all who will organize and attend the future International Chemistry Olympiads, success and happiness. Bratislava, July 2014 Anton Sirota, editor

Source note: The preface describes general editorial omissions. This Cambridge section nevertheless prints practical chemical lists, procedures and selected grading graphs, all retained. Missing original answer-booklet/NMR material is not invented.