Is chemical engineering chemistry or physics based? Musings from a college senior

College Majors Engineering Majors
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<p>Most high schoolers/college freshmen (hereafter HS/CF) tend to have the view that chemical engineering is highly chemistry based. A reasonable assumption considering the name. However, most students of chem.e. will say that it is mostly physics based. When I was a freshman in college I was told much the same. I've also seen this on CC and a few other places.</p>

<p>As I wrap up my penultimate semester as a chem.e., I've begun to look back on this advice with a little bit of disdain though. The fact of the matter is that what HS/CF know as chemistry and physics doesn't really apply to chemical engineering. Let's go through the core chemical engineering curriculum: thermodynamics, transport phenomena, separations, kinetics/reactor design, and controls.</p>

<p>My analysis will focus on the concepts critical to each class and where they are covered in HS/CF curriculum, if at all.</p>

<p>Thermodynamics - currently HS/CF chemistry classes are baby P-chem (physical chemistry) classes. There's a fair amount of exposure to things like Gibbs free energy and enthalpy balances which are certainly integral in thermo. My vote is definitely that, for the understanding of a HS/CF, thermo is chemistry based.</p>

<p>Transport - The only exposure HS/CF get to transport, to my knowledge, is by Newton's Law of Cooling, usually in physics. Maybe one could consider Bernoulli's as well but that's such a simplified equation that rarely finds application on exams in transport. Beyond that though, I see no preparation for the subject. The derivations that fluid dynamics and heat and mass transport thrive on I would argue see more influence from math and statistical mechanics (at least parts of those subjects) than what a HS/CF understands to be chemistry or physics. Perhaps one could argue that the idea of equilibrium is more fleshed out in HS/CF physics than in chemistry but this seems weak to me. My opinion: HS/CF have no real prep for transport.</p>

<p>Separations - Again the concept of equilibrium is central. At the same time though, separations are based mainly on differences between the thermodynamics of different substances. Since it's an application of thermo (mostly at least), I'm going to say chemistry is a better precursor than physics, to a HS/CF.</p>

<p>Kinetics/Reactor Design - HS/CF tend to be exposed to kinetics in some way in chemistry class. Reactor design on the other hand is more an application of transport...chemistry wins again, in my head.</p>

<p>Controls - No preparation for a HS/CF.</p>

<p>So bottom line? I would argue that telling a HS/CF that chemical engineering is more based on physics than on chemistry is misleading. At the same time though, and this is really important, the main concepts that HS/CF chemistry classes dwell on are not really applicable to chem.e. directly.</p>

<p>tl;dr: High schoolers/college freshmen get more exposure to the core concepts in chemical engineering from their chemistry classes than their physics classes but the overall image that they get from chemistry is not directly applicable to chem.eng.</p>

<p>I would love to hear other people chime in if you disagree but I hope that this can clear up some misconceptions HS/CF might be getting about the major.</p>

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<p>As a physics major, I can say without too much shame (a little, perhaps) that I’m not entirely sure what counts as physics as what counts as chemistry. The lines get blurry around thermodynamics and quantum mechanics.</p>

<p>I think you’ll find it very hard to even draw the line between physics and chemistry to answer the kinds of questions you want to answer. If you look at thermodynamics and how it was discovered… I think that most of the people doing chemistry work would have called themselves physicists, not the other way around.</p>

<p>If anybody wants to look at the majority of quantum & thermo work and see if the people called themselves chemists or physicists (or, if that’s not fair, whether they are considered to be chemists or physicists) or, better yet, has a better way of dividing up the topics, let’s hear it. I’m inclined to say that all of thermodynamics and quantum mechanics is physics proper, and chemistry is something else which resides at a higher level… and that when chemists do the low-level stuff, they’re doing physics, just like when physicists do the low-level stuff, they’re doing math, and when the mathematicians are solving problems that matter, they’re doing computer science.</p>

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<p>My point is not to try and place thermo or anything else in one realm or the other. Believe me I know how hard that is.</p>

<p>My point is to try and relate what someone in high school (or a college freshman) KNOWS to be “chemistry” or “physics” to chemical engineering because I think the advice that tends to float around is misleading, considering what they know of the subjects.</p>

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<p>I think the best way of putting it to a “HS/FC” is to say that chemical engineering is “math-based.” All college chemical engineering courses are based at their core on the idea that you can model a complex situation using the basic laws of chemistry and physics and thus analyze it mathematically. The role that physics vs. chemistry plays is in the development of these models. In reactor design, physical chemistry is more important whereas in transport phenomena Newtonian mechanics is more important. But, on the other hand, in dynamics and control, it’s all math.</p>

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<p>As a Chemical Engineer I would say it’s both, and is probably more accurate to say it’s property based than one or the other, though one will dominate. Which will dominate will depend on what you are trying to do to it.</p>

<p>A lot of what concerns an Engineer is the property or state of the chemical(s) you are utilizing and what you are going to do to them. Pumping an incompressible fluid will be a lot different than pumping a compressible fluid. What if it’s at it’s boiling point, or near it? Will I push it over the BP if I compress it? What about a heat exchanger? How will temperature changes effect the viscosity of the fluid? etc… </p>

<p>If you look at classical chemistry, it explains all of the effects you need to understand from a purely physical stand point. So, in that regards there isn’t much difference between physics and chemistry. I think a true understanding of chemistry will have with it a good understanding of intermolecular forces. Still, that’s a small branch of physics. So, to say that ChemE is physics is cheapening physics, which also includes quantum mechanics, wave mechanics, etc. (though ChemEs use wave mechanics too). </p>

<p>Anyway, I would say it’s both, about equally. Fluid Mechanics is some of my bread and butter as a ChemE, and I would say that it’s 50% Chemistry and 50% Physics.</p>

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<p>I mulled around the idea of saying this. The problem with that though is well illustrated by this xkcd comic: <a href=“http://xkcd.com/435/[/url]”>http://xkcd.com/435/&lt;/a&gt;
Everything can be “math-based” if you regress far enough. On the other hand, it IS super important that people deciding on chem.e. know the amount of math involved in it…I see your point but I just don’t think that’s a helpful way to describe the major to a HS/CF.</p>

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<p>I was a little wary of this problem when I posted but I decided not to go into it…but I guess I have to now. I feel that what Transport is depends completely on how you were taught it. My transport was COMPLETELY theory based. We derived everything from Hagen-Poiseuille to Prandtl’s mixing length…and that was just in fluids…the closest I came to applications were on tests that were really just “rederive something and plug in these numbers” with pretty faces. Based on this I might be a little biased on how exactly I view transport but I know where you are coming from.</p>

<p>Thanks for the responses guys! Keep them coming, you guys bring up very relevant points.</p>

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<p>ChemE is more math based than anything. At UT Austin, ChemE’s are required to take Physics I and II but some Engineering majors (such as PetrolE’s, EnviroE’s) dont have to take 2 Physic’s courses.</p>

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<p>I’m curious, though it’s not what you’re arguing in your post, but could you give a sort of explanation of what each of those main ChE courses are like/about? I’m a current CF, and really can’t figure out what ChE entails entirely, and am trying to decide between ChE and MechE…
Thanks!!</p>

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<p>Thermo: around half physics (The laws of thermodynamics, maxwell equations, etc.) and half chemistry (mixing, experimental data, etc.)
Transport: Mostly physics. Fluids, heat and mass are relatively similar due to the similarities of the main differential equation that is mainly based on physics laws. Some chemistry may be involved.
Separations: Some physics (The whole size calculation, etc.) but mostly chemistry. However, seriously, I dont think you need to know that much about both to do well in separations.
The rest I have no idea because I’m not there yet.</p>