Cuban National Chemistry Contest 2018
This contribution compiles the problems, solutions and results of the Cuban chemistry olympiad for high school students celebrated nationwide in 2018. The Cuban National Chemistry Contest (CNQ, Concurso Nacional de Química, official name in Spanish) is a yearly competition intended to stimulate high school students the study chemical sciences during their bachelor's. It is sponsored by the Cuban Ministry of Education (MINED, official acronym in Spanish). Tenth-, eleventh- and twelfth-graders (15-17 years old, on average) are welcome to participate. This event is preceded by the Municipal Contest at each high school and the Provincial Contest in every province of Cuba. Top winners of the latter are invited to participate in the national event. This Cuban chemistry olympiad takes place at the Vocational High School for Exact Sciences (IPVCE, official acronym in Spanish) in every province. It is organized as a two-day event in February or March every year. During the competition, the students try to solve two sets of theoretical or theoretical-practical problems elaborated by previous olympics and mentors. The qualification of the exams is performed in Havana by a tribunal integrated by selected teachers from all over the country. The highest scores are priced with gold, silver and bronze medals. Top winners can choose any career in science and the university they like the most to continue their studies with no need for additional requisites. In addition, they are part of the national pre-selection and are invited to Havana for a short training period. After a final selection round, the national team for the international chemistry olympiads is formed. As a particularity of the 2018 national contest, the Faculty of Chemistry of the University of Havana designed the problems. In the contest, there were two theoretical problem sets following the same format employed in previous years. The first-day exam was intended for all grades (common problem set) and had four problems. The second-day exam consisted of individual problem sets containing three problems per grade. Herein, the problem sets are provided in the official Spanish versions and English translations. Also, for the first time, a booklet of Preparatory Problems was elaborated to guide the preparation of students and mentors. The booklet consisted of carefully selected tasks to exercise theoretical topics of advanced difficulty. The annexes compile the current version of the syllabus for the chemistry contest.