IChO 1968, Теория — Задача 1. Problem 1

The Competition Problems from the International Chemistry Olympiads, Volume 1 (1st–20th IChO, 1968–1988), edited by Anton Sirota, IUVENTA–IChO International Information Centre, Bratislava, 2008.

Printed event: 18–21 July 1968, Prague, Czechoslovakia. This is the attributed 2008 Volume 1 compilation edited by Anton Sirota, not an obtained original jury/competitor packet. Its native preface describes recreated text/schemes/pictures, expanded early keys and selected recalculations; source errors and significant figures are retained. Reproduced for teaching with the Volume 1 attribution and native copyright conditions; Not for sale. Missing practical keys, reagent lists and experimental results are not invented.

THE COMPETITION PROBLEMS FROM THE INTERNATIONAL CHEMISTRY OLYMPIADS, Volume 1 Editor: Anton Sirota ISBN 978-80-8072-082-7 Copyright © 2008 by IUVENTA – IChO International Information Centre, Bratislava, Slovakia You are free to copy, distribute, transmit or adapt this publication or its parts for unlimited teaching purposes, however, you are obliged to attribute your copies, transmissions or adaptations with a reference to "The Competition Problems from the International Chemistry Olympiads, Volume 1" as it is required in the chemical literature. The above conditions can be waived if you get permission from the copyright holder. Issued by IUVENTA in 2008 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 Búdková 2 811 04 Bratislava 1, Slovakia Phone: +421-907-473367 Fax: +421-2-59296123 E-mail: anton.sirota@stuba.sk Web: www.icho.sk

Source qualification: Copy/distribute/transmit/adapt for unlimited teaching with Volume 1 attribution; Not for sale. No blanket commercial grant, new permission assertion or reader hold withdrawal.

Preface This publication contains the competition problems from the first twenty International Chemistry Olympiads (IChO) organized in the years 1968 – 1988. It has been published by the IChO International Information Centre in Bratislava (Slovakia) on the occasion of the 40th anniversary of this international competition. Not less than 125 theoretical and 50 practical problems were set in the IChO in the mentioned twenty years. 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. However, they did not concern the contents and language of the problems. Many of the first problems were published separately in various national journals, in different languages and they were hard to obtain. Some of them had to be translated into English. Most of the xerox copies of the problems could not be used directly and many texts, schemes and pictures had to be re-written and created again. The changes concern in particular solutions of the problems set in the first years of the IChO competition that were often available in a brief form and necessary extent only, just for the needs of members of the International Jury. Some practical problems, in which experimental results and relatively simply calculations are required, have not been accompanied with their solutions. Recalculations of the solutions were made in some special cases ony when the numeric results in the original solutions showed to be obviously not correct. Although the numbers of significant figures in the results of several solutions do not obey the criteria generally accepted, they were left without change. In this publication SI quantities and units are used and a more modern method of chemical calculations is introduced. 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. Unfortunately, the authors of the particular competition problems are not known and due to the procedure of the 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.

Nowadays many possibilities for various activities are offered to a gifted pupil. If we want to gain the gifted and talented pupil for chemistry we have to look for ways how to evoke his interest. The International Chemistry Olympiad fulfils all preconditions to play this role excellently. This review of the competition problems from the first twenty International Chemistry Olympiads 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. The edition of the competition problems will continue with its second part and will contain the problems set in the International Chemistry Olympiads in the years 1989 – 2008. The International Chemistry Olympiad has its 40th birthday. In the previous forty 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 2008 Anton Sirota, editor