It gives us great pleasure to present the fourth edition of Stoichiometry. Use of SI units is continued in this edition. Over a period of more than 26 years the book has received overwhelming response from all the users; students and practising engineers. This edition is thoroughly revised with new problems from various industries such as water treatment, oil and fats, environmental pollution, heavy chemicals, etc. Development of a cascade steam balance with optimum energy consumption is dealt at the length that we hope will be a distinctive feature. A few innovations in the chemical industry are introduced in the form of stoichiometric problems.

Use of personal computers for solving all types of engineering problems has increased. Chemical engineering is no exception. Mathematical software has taken the place of spreadsheet program-s. We have extensively used Mathcad—versatile mathematical software in solving stoichiometric problems. Simplicity of the software has enhanced the capability of an engineer in finding the optimum solution. We think that problems on optimization with Mathcad solution will be of interest to students as well as practising engineers.

We gratefully acknowledge the suggestions and comments received from various faculty members of different universities which have vastly helped us in bringing out this updated fourth edition. We are indebted to Prof. M M Sharma, Padma Vibhushan and Former Director, University Institute of Chemical Technology, University of Mumbai for his continued encouragement and support to our work. Our special thanks are due to Mr. Nishant Pandya of Nirma Institute of Diploma Studies, Ahmedabad for his supportive work in this edition. We are also grateful to various individuals, institu-tions and organizations for providing us copyrighted material and permitting us to reproduce them in this edition.

We are sure that all the users—students as well as our colleagues in industry and in academia—will find this edition more useful. All suggestions for further improvement are welcome.

B I BHATT
S M VORA