The era of the industrial revolution 4.0 is an era of digitalization in various fields, especially in the field of education, so that a teaching material is needed that can increase student activity in learning. The purpose of this research is to determine the validity and practicality of salt hydrolysis e-module based on guided discovery learning. The development of e-modules uses a type plomp development model which consists of three steps: (1) preliminary research, (2) prototyping, and (3) assessment phase. The research instrument used a form validity and practicality sheet. Data were analyzed by Aiken's V formula. This e-module was validated by 3chemistry lecturers of FMIPA UNP, 2 informatics engineering lecturers of UNP, and three chemistry teachers of SMAN 14 Padang. Practicality tests were conducted on 3 chemistry teachers of SMA 14 Padang and twenty-eight twelfth grade students of SMAN 14 Padang. The value validity of construct and the validity of the media expert, the Aiken's V average was 0.90 and 0.87 with high validity categories. The value of practicality tests by teachers and students, the Aiken's V was 0.93 and 0.85 with high practicality categories. Based on the results of this research, it can be concluded that development of salt hydrolysis e-module based on guided discovery learning was valid and practical.

Keywords : Guided Discovery Learning, E-Modul, Plomp Development Model, Salt Hydrolysis