Abstract: Kinetic isotope effect (KIE) has emerged as a new topic in chemistry competitions both domestically and internationally in recent years. This paper elucidates the origins of first-order and second-order KIE, starting from the perspective of classical transition state theory, based on the potential energy curve and zero-point vibration energy. The role of KIE in the study of reaction mechanisms is briefly discussed. By analyzing relevant exam questions from both domestic and international chemistry competitions, the examination perspectives on KIE are identified, highlighting the continuity between domestic and international competitions. Finally, this paper offers reflections and suggestions for teaching KIE in the context of competitive exams, providing valuable insights and references for educators involved in competition training.

Key words: Kinetic isotope effect, Chemistry competition, Question analysis