Overview
The Olimpíada Brasileira de Química (OBQ) is Brazil's national chemistry olympiad for secondary students, run by the Programa Nacional Olimpíadas de Química. Its results lead to the teams that represent Brazil at international chemistry olympiads. A separate junior competition, the OBQ Júnior, covers lower years.
Who can apply
The OBQ is for students enrolled in Ensino Médio in public or private schools. Students enter through state olympiads, and participants must be from states with an appointed state coordinator.
Levels or stages
Modalities
Modalidade A: 1st and 2nd year of Ensino Médio
Modalidade B: 3rd year of Ensino Médio
Stages
Students first compete in state olympiads, where state coordinators choose who goes to the national phase. Each state can send up to 140 students, 80 in Modalidade A and 60 in Modalidade B, and at least 20 places are reserved for public school students from schools without selective admission. The national exam is Phase III. Top performers then go through further phases (IV, V and VI) that involve laboratory knowledge and specialised courses, ending in the selection of Brazil's representatives for international chemistry olympiads.
OBQ Júnior
For students in years 6 to 9 of Ensino Fundamental, in public and private schools, with no age limit. Phase I is held in person at the school and lasts two hours. Phase II is online and is open to the 50 best students per school in each modality, who must have scored at least 50% in Phase I.
Exam pattern
The Phase III national exam is in person and lasts 4 hours. It has theoretical questions with difficulty-weighted scoring, and a wrong objective answer loses 0.5 points. Scientific calculators are allowed, but programmable calculators and electronic devices are not.
Fees
No entry fee is stated for the main OBQ. A grade appeal costs R$75 per question, waived for public school students.
Preparation tips
Practise past national papers, including the objective questions where wrong answers cost points.
Build a solid base in general, organic and physical chemistry, and practise laboratory reasoning.
Can I register directly for the national phase?
No. Students qualify through their state olympiad, and each state sends a limited number.
Are calculators allowed?
Scientific calculators are, but programmable calculators and electronic devices are not.