This book is designed for the first-year engineering undergraduate students. This book aims to impart to students an in-depth knowledge of various aspects of chemistry as applied to engineering. This textbook contains 7 chapters covering all the disciplines of Engineering Chemistry and deals with various branches of chemistry - physical, inorganic, organic, and general etc. This note covers the following topics: Organic Reactions and Drug Molecules, Polymers, Material chemistry, Electrochemistry and Batteries, Corrosion and its Corrosion Control, Water Treatment, Phase Rule.