Chemistry and Chemical Engineering
School of Chemistry and Chemical Engineering, Jiangsu Normal University
What is chemistry about
The different kinds of matter that compose the universe are termed materials. Each material has its own distinguishing characteristics, which is termed its properties. These properties enable the material to be recognized or separated from other materials. (Miriam, 2000) The study of materials is the joint concern of chemistry and physics. These two sciences are so closely related that no one can learn very much about either without considerable training in the other. In many of their applications it is hard to tell where the one science leaves off and the other begins.
Roughly stated, physics is concerned with the general properties and energy and with events which result in what are termed physics changes. Physics changes are those in which materials are not so thoroughly altered as to be converted into other materials distinct from th
ose present at the beginning. (Sadeghi, B. 2008) Chemistry, by contrast, tends to focus on the properties of substances and the interactions between different types of matter, particularly reactions that involve electrons. (Karimi, A. R. 2006) Who but a chemist would ever guess that common salt can be resolved into a greenish gas and silvery matal? Or that two odorless gases, nitrogen and hydrogen, can be combined to form ammonia? Or that ordinary air and water can be converted into nitric acid? Or that coal tar contains ingredients that can be transformed into dydstuffs and perfumes? Such thoroughgoing transformations, in which all the properties of a material are altered, so that a completely different material is obtained, are called chemical transformations, chemical changes or chemical reactions. Chemistry as an art is concerned with identifying, seperating and transforming materials, in applying them to definite uses. (Kantevari, S. 2007) Chemistry as a science is a manner of thinking about transformations of materials which helps us to understand, predict and control them. It furnishes directing intelligence in the use of materials.
The scope of chemistry
Chemistry is the branch of science which deals with the properties, composition and the structure of matter. It also deals with chemical reactions, changes in matter, and the principles which govern these changes and is sometimes called the “central science” because it relates to so many areas of human endesvor and curiosity. (Lingaiah, N. 2007) Chemists who develop new materials to improve electronic devices such as solar cells, transistors, and fiber optic cables work a the interfaces of chemistry with physics and engineering. Those who develop mew pharmaceuticals for use against cancer or AIDS work at the interfaces of chemistry with pharmacology and medicine. Many chemists work in more traditional fileds of chemistry. Biochemists are interested in chemical processes that occur in living organisms. Physical chemists work with fundamental principles of physics and chemistry in an attempt to answer the basic questions that apply to all of chemistry: why do some substances react with one another while others do not? How fast will a particular chemical reaction occur? How much useful energy can be extracted from a chemical reaction? Analytical chemists are investigators; they study ways to seperate and identify chemical substances. Many of the techniques developed by analytical chemists are
react withused extensively by environmental scientists. Organic chemists fouse their attention on substances that contain carbon and hydrogen in combination with a few other elements. The vast majority of substances are organic chemicals. Inorganic chemists fouse on most of the elements other than carbon, though the fileds of organic and inorganic chemistry overlap in some ways. (Saikat, D. S. 2008) They work in a lab, in a research environment, asking questions and testing hypotheses with experiments.
Authough chemistry is considered a “mature” science, the landscape of chemistry is dotted with unanswered questions and challenges. Moden techenology demands new materials with unusual properties, and chemists must devise new methods of producing these materials. Modern medicine requires druges targeted to perform specific tasks in the human body, and chemists must design strategies to synthesize these drugs from simple starting materials. (Subhasis, S. 2009) Society requires improved methods of pollution control, substitues for scarce matericals, nonhazardous means of disposing of toxic wastes, and more efficient ways to extract energy from fuels. Chemists are at work in all these areas.
Chemical engineering
Chemical engineering is the profession concerned with the creactive application of the scientific principles underlying the transport of mass, energy and momentum, and the physical and chemical change of matter. (Mazaahir, K. 2007) The broad implications of this definition have been justifed over the past few decades by the kinds of problems that chemical engineers have solved, though the profession has devoted its attention in the main to the chemical process industries. As a result chemical engineers have been defined more traditionally as those applied scientists trained to deal with the research, development, design and operation problems of the chemicals, petroleum and related industries. ( Majid, M. H. 2007) Experience has shown that principles requried to meet the needs of the process industries are applicable to a significantly wider class of problems, and the modern chemical enineer is bringing his established tools to bear on such new areas sa the environmental and life sciences.
Chemical engineering developed as a distinct dsciplne during the twentieth century in answ
er to the needs of a chemical industry no longer able to operate efficiently with manufacturing processes which in many cases were simply larger scale versions of laboratory equipment. (Sivakumar, K. 2010) Thus, the primary emphasis in the profession was initially devoted to the general subject of how to use the results of laboratory experiments to design process equipment capable of meeting industrial production rates. This led naturally to the characterization of design procedures in terms of the unit operations, those elements common to many different processes. The basic unit operations include fluid flow, heat exchange, distillation, extraction, etc. A typical manufacturing process will be made up of combinations of the unit operations. Hence, skill in designing each of the units at a production scale would provide the means of designing the entire process. The unit operations concept dominated chemical engineering education and practice until the mid-1950s, when a movement away from this equipment-oriented philosophy toward an engineering science approach began. This approach holds that the unifying concept is not sepcific processing operations, but rather the understanding of the fundamental phenomena of mass, energy and momentum transport that are common to all
of the unit operations, and it is argued that concentration on unit operations obscures the similarity of many operations at a fundamental level. (Janis, R. A. 1987)
Although there is no real conflict between the goals of the unit operation and engineering science approaches, the latter has tended to emphasize mathematatical skills and to de-emphasize the design aspects of engineering education. (Bossert, F. 1981) Such a conflict need not exist, and recent educational effort has been directed toward the development of the skills that will enable the creactive engineering use of the fundamentals, or a synthesis of the engineering science and unit operations approaches. One essential skill in reaching this goal is the ability to express engineering problems meaningfully in precise quantitative terms. Only in this way can the chemical engineer correctly formulate, interpret, and use fundamental experimens and physical principles in real world applications outside of the laboratory. This skill which is distinct from ability in mathematics, we call analysis. 

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