Cuban National Chemistry Contest 2019

This contribution compiles the problems, solutions and results of the Cuban chemistry olympiad for high school students celebrated nationwide in 2019. 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. 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 contestants 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. Herein, the problem sets of the Preparatory Problems booklet, the national exams and their solutions, and the results of the Cuban students in the national and international competitions are provided in the official Spanish version and English translation.