Chemistry versus Chemical Engineering

By Nikhilesh Mathur

When I first read years ago in the school classroom that hydrogen and oxygen can be reacted together to form water, I felt as if chemistry is the only subject which helped in creating this universe and that myself and all my then fellow students in the classroom have come to know about a big secret. After studying some more reactions most of us students were on top of the world. I am sure the present day school students of science must also be having a bit of such a feeling though they are a bunch of much more well informed than what the students were in earlier times.

Yes, Chemistry does create a long lasting impact on the minds of young students as after gaining insight into reactions one develops a feeling of having a super ability to make products in an easy fashion. Science drives us into doing several interesting things. Bringing test tubes home and heating some or the other substance in it on a domestic stove gave a feeling of being a research scientist capable of churning out products like a magician unfurling a handkerchief to release pigeons. 

Many of the present day students must still be carrying the ideas of chemistry when they willingly opt for chemical engineering in college. Since our education system has still not awaken to clearing the mist in the minds of the young school students concerning engineering subjects. We very conveniently relate to chemical engineering as an extension of chemistry. Little do we realize that chemistry is as different from chemical engineering as is a river from an ocean. Yes, both the river as well as the ocean contains primarily water, and so is the similarity between chemical engineering and chemistry. The similarity rather ends here.

Chemical Engineering is application of chemistry in real world

Chemical engineering utilizes the reactions of chemistry, but then it is too big a monument to confine itself to just reactions.

Let us try to understand the difference between chemistry and chemical engineering assuming that all of us are sitting in the higher secondary class room of our school. Let us bring our mind set to that stage once again and find out how much we think of chemical engineering is actually true. So we begin with that basic interesting equation which explains us about two molecules of hydrogen mixing with one molecule of oxygen to make two molecules of water.  And so conversely speaking dissociation of water would yield hydrogen and oxygen gases.

Let me ask, if I give you water and ask you to pass electric current in it would you get hydrogen gas and oxygen gas separately?

Many might call this a stupid act, but then my advice is, never even think of trying this by any means because hydrogen and oxygen form a highly explosive mixture together. So there we are. How then do we get these gases from water?

At this point chemical engineering comes into picture to make the process happen on an industrial platform which otherwise appeared to be simple chemistry. It is chemical engineering which tells us that hydrogen and oxygen combine in a well spread out range of volumetric percentages to create an explosive mixture and therefore they need to be separated in the electrolytic cell equipped for water dissociation by means of a diaphragm. The chemical engineering process explains us that it is not the usual alternating current which can dissociate water. One requires Direct Current (DC) at a certain voltage to make this happen. The purity of the separated gases needs to be maintained in the process and the main input i.e. the driving force of the reaction is the electric power. Hence the consumption of power per unit of gases produced becomes a parameter which needs to be economically controlled to make the process successful on commercial basis.

Chemical engineering is Chemistry, Mechanics and Economy mixed together

Chemistry does not directly guide us into finding more economical sources of the production of hydrogen gas. It is chemical engineering which educates us that hydrogen gas is a by-product of a caustic soda manufacturing plant and produces the same at much less cost than what a power driven electrolytic cell does. Chemical engineers can therefore play a strong role in advising an entrepreneur about the most adequate location of the manufacturing plant i.e the one near to the raw material sources. They are trained to formulate processes with equipments, process conditions and inputs to achieve the desired quantum and quality of a product which chemistry has outlined.

Chemistry makes us understand the properties of the various chemicals, their uses, their reactivity with other chemicals and can provide a guideline for the process of manufacturing. But manufacturing is just not simply reacting of two or more substances. It requires an adequately designed equipment and maintenance of favorable process conditions for the reaction to proceed un-interruptedly in the forward direction. The process conditions needs to be maintained in a precise manner. Any mild disturbance in one parameter can cause huge variation in the quality of the resulting product. Only chemical engineering knowledge can keep the processes on the right track. Yes, chemistry can surely tell us that cooling water is necessary to cool the reaction mixture due to its exothermic nature. But do we have that much water to waste in cooling the reactions continuously by draining this water which became hot after heat exchange. No, common sense tells us that we need to re-circulate the same water. But then how do we recycle the same hot water? We cannot, until we cool it back to the near ambient temperature. So we require cooling towers which can be designed only after using the chemical engineering principles correctly. What the chemistry tells us about chemicals, product & processes cannot be accomplished without using chemical engineering principles effectively.

Chemical engineering is an art 

Let us be clear on one point. Chemical engineering is just not an extension of chemistry. Chemistry is pure science whereas chemical engineering is not science alone. It is both an art as well as science which involve several facets and promises to deliver a result which is nearly impossible by the use of any individual science application or any other engineering application in isolation.

Myth vs reality

It is a myth that chemical engineering involves only chemistry. It actually involves knowledge of most of the other subjects including economics and not just only the science subjects. For example cooling/chilling system requires the knowledge of thermodynamics/refrigeration, fabrication of equipment require the knowledge of metallurgy of the metals. Mechanical engineering has a ‘say’ in all aspects of design and operation of the machines such as agitators, grinders, size reduction machines, heat exchangers, mass transfer equipment and economics plays its role in evaluating the cost of the new product and in deciding its right sale price.

Chemistry and Chemical Engineering are incomplete without each other

I would be very discreet in mentioning that chemistry is the backbone of several process and products and without its knowledge one would never be able to carry out any research or develop new products which have made our lives easier and more enjoyable. The thought of comparing chemistry with chemical engineering is never to ‘belittle’ these important science subjects which keep helping us in giving all those products we need to survive on planet Earth. There is no doubt about the importance of chemistry in making our planet a place to enjoy. It is a fruit of its own special kind as is chemical engineering and it is surely not wise to compare the two fruits each of high nutrition value, and particularly when one of them gives rise to the thought processes for the other one.

Without chemistry chemical engineering would strive to get the right feed material and without chemical engineering chemistry alone might not be able to take all the chemicals to their most useful shape / condition. The idea which the young students should pick up here is that chemical engineering might begin its journey from chemistry, but then it travels far and wide and keeps taking the cue from chemistry whenever it requires. “Comparisons deplete the actuality of the things compared”……mentioned William S. Wilson, and we would end in pain if we do this as any such comparison would reduce the educational value of both these subjects.

Career prospect: Chemistry vs Chemical Engineering

• It is necessary to understand here that a simple graduation in chemistry might give limited options in the career, whereas B.Tech in chemical engineering can provide wider options.
• With chemistry, the students would do better if they pursue post-graduation and then doctorate, while with graduation in chemical engineering one can get a job right away or can also divert into the management field by doing MBA.
• Candidates who have an eye for management oriented job are advised to opt for chemical engineering.
• M.Tech in chemical engineering will provide scope in the research and education field.
• Giant industries engaged in manufacturing have round the clock factory operations and as employers they have now begun choosing from chemical engineering graduates for controlling their shift operations.
• Those with chemistry background either get a job in laboratories or in the specialized reaction areas where chemistry of reactions is more important than the installed chemical engineering unit operations.

The basic point is to understand the real worth of both chemistry and chemical engineering as individual subjects, and while doing so a student must try to probe as to which of the two would make his/her mind click more. Education of chemistry helps in research oriented work, developing products at the laboratory scale, getting motivated by the mere thought of creating a new product or detecting a new usability of an age old chemical. On the other hand, chemical engineering would help in fulfilling the desire to actually produce a product for consumption on a large scale and feel the enjoyment of seeing the transformation of an odd substance into a precious value added product.

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About the author:

Nikhlesh Mathur, comes with a vast experience spanning 30 years in the chemical and allied industries. He is an MBA and has done his Chemical Engineering from NIT Rourkela. He is working in the senior management cadre in the private sector. He is also a Member of the Institution of Engineers (India). He is also a keen student of Astrology and keeps himself amused by studying the moods of celestial bodies. He became a published author with his recent book, Learning Chemical Engineering for Process Industries published by Authorspress (2015).