Fostering SDG 4 Quality Education: Diagnostic Assessment of Grade 10 Students' Stoichiometry Difficulties in the Merdeka Curriculum

In alignment with Sustainable Development Goal 4 (SDG 4) for quality education and the demands of Indonesia’s Merdeka Curriculum, mastering stoichiometry in Phase E is crucial, yet students frequently struggle with its combined conceptual and quantitative demands. This study aims to investigate students' learning difficulties in stoichiometry, focusing on challenging concepts and their underlying contributing factors. Using a quantitative descriptive approach, the research involved 26 Class X-K students at SMA Negeri 1 Pontianak. Data were collected using a three-tier diagnostic test and follow-up interviews. The results revealed that 75.13% of students demonstrated non-scientific conceptions, predominantly characterized by misconceptions and a lack of conceptual knowledge in stoichiometry. The highest difficulty rates occurred in stoichiometric calculations (90.50%) and substance concentration (83.00%), followed by empirical and molecular formulas (77.00%), while the mole concept showed a moderate difficulty rate of 50.00%. These difficulties stemmed from internal factors specifically low learning motivation, weak conceptual understanding, and inadequate mathematical skills as well as external factors related to instructional methods. In conclusion, calculation-intensive topics present the primary barrier to mastering stoichiometry, emphasizing the urgent need for pedagogical interventions that integrate mathematical reinforcement and student-centered learning strategies to support meaningful learning outcomes