IChO Problems and Solutions
First held in 1968 in Czechoslovakia, between three countries: four theory tasks, no experiment and no medals. It now runs a theoretical and a practical exam, and every host publishes a preparatory problem booklet months in advance.
2026
Uzbekistan
Theory 9 problems
1 Theory A journey through time: The secrets of Avicenna Problem Solution IChO 2026 Theory problem 1, A journey through time: The secrets of Avicenna 2 Theory Kinetics of the Belousov-Zhabotinsky reaction Problem Solution IChO 2026 Theory problem 2, Kinetics of the Belousov-Zhabotinsky reaction 3 Theory Into Reticular Chemistry Problem Solution IChO 2026 Theory problem 3, Into Reticular Chemistry 4 Theory The nuclear past of Uzbekistan Problem Solution IChO 2026 Theory problem 4, The nuclear past of Uzbekistan 5 Theory Cardiolipins Problem Solution IChO 2026 Theory problem 5, Cardiolipins 6 Theory Carbon Nanorings Problem Solution IChO 2026 Theory problem 6, Carbon Nanorings 7 Theory Nitrogen Fixation Problem Solution IChO 2026 Theory problem 7, Nitrogen Fixation 8 Theory Recycling of Carbon Dioxide Problem Solution IChO 2026 Theory problem 8, Recycling of Carbon Dioxide 9 Theory Cyclodextrin Chemistry Problem Solution IChO 2026 Theory problem 9, Cyclodextrin Chemistry Practical 3 problems
10 Practical Synthesise and analyse (A new complex problem) Problem Solution IChO 2026 Practical problem 10, Synthesise and analyse (A new complex problem) 11 Practical Atlas of Enzymes Problem Solution IChO 2026 Practical problem 11, Atlas of Enzymes 12 Practical The Adventures of Hodja Nasreddin Problem Solution IChO 2026 Practical problem 12, The Adventures of Hodja Nasreddin
2025
United Arab Emirates
1 Isocaryophyllene, clovene, and humulene not published 2 Rapamycin - A molecular glue not published 3 Lanterns and the Burj Khalifa not published 4 The life of tennis balls not published 5 Solar-powered multi-stage flash desalination not published 6 Solar energy conversion by CO2 reduction not published 7 Dubai crude oil not published 8 Carbon monoxide: deadly poison or promising therapeutic agent? not published 9 Enzymes and cofactors not published 10 A complex problem not published 11 Exploring the AminOasis not published 12 Rf you ready to spot the answers? not published
2024
Saudi Arabia
1 Ammonia not published 2 Electronic nose not published 3 Tyrosinase not published 4 Potassium not published 5 Unknown not published 6 Penicillin not published 7 Sabic not published 8 Safflower not published 9 Porphyrin complexes not published 10 Indicators not published 11 Titration on a balance not published
2023
Switzerland
1 Molecular Imaging not published 2 Electrochemical CO2 Reduction not published 3 Artificial Photosynthesis not published 4 Fluorinated and Hypervalent Compounds not published 5 Hydrodesulfurization not published 6 Direct Conversion of Methane to Methanol not published 7 Enzyme Kinetics not published 8 Nazarov Reaction not published 9 Electrolysis in Organic Synthesis not published 10 Switzerland - The Country of Pharmaceuticals not published 11 Organic Synthesis: Bleach, a Chameleonic Reagent not published 12 Titration Tango not published 13 Beauty in Simplicity not published
2022
China
1 Rapid and Visual Nucleic Acid Testing for COVID-19 not published 2 Chromium in Ancient and Modern Times not published 3 Capture and Transformation of Carbon Dioxide not published 4 A New Journey for Ancient Sulfur not published 5 Interconversion among Nitrogen Oxides not published 6 Enabling Phosphines not published 7 Organic Molecules in Life not published 8 Amazing Chiral Spiro Catalyst not published 9 Total Synthesis of Capitulactone not published
2021
Japan
1 Hydrogen at a Metal Surface not published 2 Isotope Time Capsule not published 3 Lambert-Beer Law? not published 4 The Redox Chemistry of Zinc not published 5 Mysterious Silicon not published 6 The Solid-State Chemistry of Transition Metals not published 7 Playing with Non-benzenoid Aromaticity not published 8 Dynamic Organic Molecules and Their Chirality not published 9 Likes and Dislikes of Capsule not published
2020
Turkey
1 Two Beauties of Turkey: the Van Cat and the Ankara Cat not published 2 A Tale of a Reactive Intermediate not published 3 (±)-Coerulescine not published 4 Symmetry Does Matter! not published 5 Konya, Carrot, Beta-Carotene, Vitamin-A, Immune System, Vision not published 6 Thermodynamics through an Interstellar Journey not published 7 Phthalocyanines not published 8 Boron Compounds and Hydrogen Storage not published 9 Quantification of Heavy Metal Ions not published
2019
France
1 Infinite well and butadiene not published 2 Hydrogen production by water-splitting not published 3 About silver chloride not published 4 From black powder to the discovery of iodine not published 5 Complexes for the formation of nanomachines not published 6 Characterization of a block-copolymer not published 7 Ring motion in a [2]catenane not published 8 Identification and synthesis of inositols not published 9 Synthesis of levobupivacaine not published 10 Greening the oxidation of nitrobenzaldehyde not published 11 The iron age of wine not published 12 Wine for keeping not published
2018
Slovakia & Czech Republic
1 DNA not published 2 Repatriation of remains in the middle ages not published 3 Emerging electro-mobility not published 4 Column chromatography of radioactive copper not published 5 Bohemian garnet not published 6 Let’s go mushrooming not published 7 Cidofovir not published 8 Caryophyllene not published 9 Haloform reaction with bleach not published 10 A glowing clock reaction not published 11 Mineral water identification not published
2017
Thailand
1 Production of propene using heterogeneous catalysts not published 2 Kinetic isotope effect (KIE) and zero-point vibrational energy (ZPE) not published 3 Thermodynamics of chemical reactions not published 4 Electrochemistry not published 5 Phosphate and silicate in soil not published 6 Iron not published 7 Chemical Structure Puzzles not published 8 Silica Surface not published 9 Into the Unknown not published 10 Total Synthesis of Alkaloids not published 11 Twist & Chirality not published 12 Acid-base indicator and its application for pH measurement not published 13 Calcium iodate not published 14 Elaborating Carbon Framework not published
2016
Georgia
1 Problem 1 not published 2 Problem 2 not published 3 Problem 3 not published 4 Problem 4 not published 5 Problem 5 not published 6 Problem 6 not published 7 Problem 7 not published 8 Problem 8 not published 10 Determination of fluoride and chloride content in mineral water not published 11 Identifying flavors and fragrances not published
2015
Azerbaijan
1 New and well-forgotten old refrigerants not published 2 Coupling of chemical reactions not published 3 Two binding centers – competition or cooperation? not published 4 From one yellow powder to another: A simple inorganic riddle not published 5 Indispensable glucose not published 6 Bread is the stuff of life not published 7 Not by bread alone not published 8 Oil for Life and Life after Oil not published 9 Tuning bromination selectivity by catalysis not published 10 Analysis of the solution of a chromium – vanadium alloy not published 11 Kinetic determination of Diclofenac (DCF) not published
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