<![CDATA[Abstrak Penelitian ini bertujuan menganalisis pengaruh model pembelajaran Problem Based Learning (PBL) terhadap hasil belajar siswa pada materi asam basa. Penelitian menggunakan metode eksperimen dengan desain One Group Pretest–Posttest Design. Subjek penelitian terdiri atas 21 siswa kelas XI yang dipilih menggunakan teknik sampling jenuh. Instrumen penelitian berupa tes esai sebanyak 10 butir yang telah memenuhi validitas isi dengan nilai rata-rata sebesar 87,25%. Data dikumpulkan melalui pretest dan posttest, kemudian dianalisis menggunakan statistik deskriptif, uji normalitas Shapiro–Wilk, uji hipotesis dilakukan menggunakan uji Paired Sample t-test ,dan besar pengaruh menggunakan N-Gain. Data pretest dan posttest berdistribusi normal dengan nilai signifikansi > 0,05, Hasil uji paired sample t-test menunjukkan nilai signifikansi Sig. < 0,05, yang mengindikasikan adanya pengaruh signifikan model pembelajaran PBL terhadap hasil belajar siswa sedangkan nilai N-Gain sebesar 0,39 termasuk kategori sedang. Dengan demikian, model pembelajaran Problem Based Learning (PBL) efektif meningkatkan hasil belajar siswa pada materi asam basa. Kata Kunci: Problem Based Learning (PBL), hasil belajar, asam basa, Abstract This study aimed to examine the effect of the Problem-Based Learning (PBL) model on students' learning outcomes in the acid–base topic. The study employed an experimental method using a One-Group Pretest–Posttest Design. The participants consisted of 21 eleventh-grade students selected through total sampling. The research instrument was a 10-item essay test that had been validated by experts, with an average content validity score of 87.25%. Data were collected through pretest and posttest administration and analyzed using descriptive statistics, the Shapiro–Wilk normality test, and the paired-samples t-test for hypothesis testing, while the magnitude of improvement was measured using the N-Gain index. The pretest and posttest data were normally distributed (p > 0.05). The results of the paired-samples t-test showed a statistically significant difference (p < 0.05), indicating that the PBL model had a significant effect on students' learning outcomes. Furthermore, the N-Gain score of 0.39 was categorized as moderate. Therefore, the Problem-Based Learning (PBL) model was effective in improving students' learning outcomes in the acid–base topic. Keyword: Problem-Based Learning (PBL), learning outcomes, acid–base]]>
