Abstract. This research was carried out to evaluate students' attitudes toward learning and doing Chemistry activities using web-lab experiments through pre-survey and post-survey assessments. It also assesses their performance in the subject through pretest and posttest and analyzes the influence of web-based laboratory activities on students’ attitudes and performance in Chemistry. This research utilized the experimental design, employing the pre-test and post-test strategies. The respondents are the 154 Senior High School students of the Science Technology Engineering and Mathematics (STEM) strand of St. Paul University Dumaguete. However, the data collected from the control group was excluded from this analysis to concentrate on the 79 respondents of the experimental group. This allows for a comprehensive examination of the web-based laboratory experiment's potential benefits on the attitudes and performance of students towards chemistry. The validated survey questionnaire and pretest and posttest questions were used to gather the data. Statistical tools used in the study were Mean, Wilcoxon Test, Spearman’s Rank Order Correlation, Paired Samples t-test, and Cohen’s d. The results revealed that web-based laboratory experiments effectively improve students' attitudes and performance in chemistry. The perceived value of Chemistry emerged as a crucial factor influencing performance in laboratory tasks. Web-based instruction makes learning fun, emphasizing its real-world application and increasing students’ overall value and positive attitude in Chemistry.

Keywords: Chemical concentrations; Conventional laboratory; Web-based laboratory.