8th Grade Science as a Path to Madness February 9, 2010
Posted by gaussling in Education, Science, Science Education.add a comment
So it happens that my kid is in 8th grade and is studying chemistry for the first time in earnest. As luck would have it, the kid’s teacher is of Hatian extraction and is on some kind of leave of absence either due to illness or possibly because 3 family members perished in the quake. I don’t know. This fellow seems to be a good teacher.
His replacement, however, is not very good. In fact, his replacement is … awful.
For the first time, I had a serious discussion with a principal about a teacher’s performance. The principal is apparently aware of the substitutes classroom foibles and sins of omission. The principal’s own son is a student in that class and so he has a personal interest in the matter.
So, after some time with the kid at the whiteboard in our basement last night, it dawned on me that I had completely forgotten how utterly strange atomic theory and the chemical phenomena that derive from it really are. It is all quite abstract and maybe even a little weird.
The curriculum gives some emphasis to understanding the concept of pH. Alright. But this requires some ideas about logarithms and exponents. Then there is the matter of chemical equilibrium. While kids are wrestling with the math, you are also trying to tell them that only a very small number of water molecules actually come apart into ions. But the kids need to be comfortable with the notion of ions and charge.
But, what makes hydrogen ion different from hydroxide ion, really? And why does hydroxide ion have the negative charge? How is it that acids corrode iron to form H2, but hydroxide does not? What does it mean to be an acid? What does it mean to be a base?
You can try to use structural models of sulfuric acid rather than line formulae like H2SO4 to appeal to the idea that these are little things with attachments that do things. One could argue that it is a bit more concrete that way- little structures with parts that are detachable. But as soon as you start drawing structures, you run into a rats nest of intermeshed concepts relating to bonds and lone pairs. Then there is the bloody octet rule, covalency, and orbitals!!!
For crying out loud!! How does anybody learn this stuff?? The learner has to absorb 20 abstract concepts almost simultaneously to begin to “get” chemistry. Even worse, if a chemist/parent teaches the kid about a concept, almost certainly it will not mesh with curriculum, leading to confusion and tears for the teacher and the student.
I taught orgo to college sophomores, but evidently 8th grade chemistry eludes me. I’m just too dense to grasp the level of abstraction they will accept. Oh! To have an hour with Piaget!
xkdc cartoon February 2, 2010
Posted by gaussling in Humor, Whimsy.1 comment so far
Yeah, you find pi in the funniest places.
This is how science really works.
That’s Show Biz January 29, 2010
Posted by gaussling in Arts & Entertainment, Theater.add a comment
A few of us have formed a theatre company. It is a not-for-profit operation. It’s too sketchy to expect a profit in theatre anyway. May as well admit that up front. Among the founders is a playwright.
Our first performance as a theatre company is coming up soon and was written by our in-house writer. It is a play called Cow Dung Dust. The story takes place among hitchhikers in the back of a cattle trailer headed for California along Route 66 ca 1970. The same writer wrote the play Beets, which we performed in Loveland, Colorado, last spring. It was actually quite a hit.
The first public airing of Cow Dung Dust will be performed as readers theatre. This is much like radio mystery theatre with actors reading from a script and with a bit of lighting and sound effects. Since we do not have a few kilobucks to throw into set pieces, costumes, and lighting, readers theatre is what we are able to do first thing. It is like a garage band having to do a bunch of lean and mean gigs in order to build up a following. I have a feeling that after the readers theatre we’ll be keen to do a stage performance of it. This approach gives the playwright a chance to tweak the script after he sees the audience react to it.
The next performance will be a well known stage play. This requires paying royalties for use of the script, which is typically copywritten tighter than a piano wire. Should be fun. It is so wonderfully different from chemistry, I can’t help but enjoy it.
The Passive Aggressive Opera. Act I. Reverse Delegation. January 27, 2010
Posted by gaussling in Business, Chemical Industry, Chemistry, Science.add a comment
Supervision of people is one of the things that a chemist can look forward to on the way up the ladder. The people who report to you may be called staff or report-to’s. The term “my employee” should be reserved for use by those who sign paychecks. What ever you call them, they’re your group.
I’m not going to write about how to manage people. After many years of doing it I’m not sure I really understand it yet. All I can say is that every day some people show up and expect you to keep them busy.
Okay, I’m just kidding. But I am serious about the mysteries of management of people. I think most would agree that the best way to lead people- the way most of us would prefer to be lead- is by setting a good example. It’s pulling instead of pushing. Inspired leadership by a charismatic and talented individual is preferable but, unfortunately, rather unusual.
There are many theories of management and more management consultants than you can count out there urgently interested in telling you how to manage your staff. All you have to do to sample the many management theories is to stroll through the business section of the local bokstore. Every one of the authors will trot out a set of polished anecdotes that outline the path to their own professional enlightenment.
Chemists on the management track may move in many directions in a business organization. Most obvious is management of a technical activity like R&D. But there is also management opportunity in scale-up, pilot plant, production, QA/QC, and analytical services activity. Management of the production side is sure to include inventory and warehouse control, regulatory affairs, personnel issues, engineering, and maintenance. Itis not uncommon for engineers to head the production unit.
On the less technical side is sales, procurement management, and business development. While perhaps less technical, the chemical industry needs (requires, really) chemically savvy people to handle purchasing and sales activity. It is not uncommon for sales oriented people to ascend into the upper reaches of management generally and the chemical industry is no different.
What is perhaps different in the chemical industry is that chemists are often disfavored in the track to the CEO’s office by their lack of economic training. The ability to deliver big projects on time and on budget is a key attribute and engineers are especially well positioned to do this very thing. The bigger the scale of operations the greater the likelihood that an engineer will be in charge. Or so my experience has been.
Among those I have observed, managers who have exemplary experience in controlling the big money are often the ones groomed for executive leadership. And the big money is in big projects with lots of sales volume. It is the source of life giving cash. That which makes the corporate world go ’round. The elusive spondulix.
But back to management. One of the most vexing aspects of managing people is that you have to manage people. People are complex and prone to nonlinear behavior. Everybody knows this. But the manager is tasked with using human resources to provide some kind of work product on time and on spec. How do you compel people to do this every day?
The threat of termination is a good though heavy handed tool to compel folks to do their job. But this is a tool that can also backfire. Frequent termination of people is stressful and puts the manager in the position of having to be in a more or less constant training mode. Best to hire hard working people who are self-starters.
I have not found a simple formula for management. All I can do is to support down and fight up. I fight for resources and reasonable expectations. I treat people in the most hospitable manner I can muster and in return I expect the same.
One of the most annoying behaviors is the phenomenon of “reverse delegation”. You ask your report-to to do a particular thing. In reply you are told that they can only do the thing if you first make some arrangements. You have to get this or that ready, or perhaps you have to write an SOP or work instruction, or maybe even they will need to fly to a hotel in Vegas or Orlando to take some training course. It is all push-back: a kind of passive aggressive behavior meant to deflect your attention.
What I have found is that these reverse delegators may be very concrete in their approach to the unfamiliar. They will assert that they must possess a good deal of skill to even begin some new task. Sometimes this is true. But often it is only a matter of time on task to make some good progress. The hard part for some of us is dealing with the simple truth of the matter. Not everyone desires being collegial and operating on the give and take level of colleague. A lot of folks only respect the brusque barking of orders by a Captain Bly figure and the sight of a**holes and elbows hustling in the plant. I would have been Captain Kangaroo, not Bly. It’s just a fact.
On the pitfalls of process intensification January 5, 2010
Posted by gaussling in Chemical Industry, Chemistry, Economics, Safety, Technology.5 comments
As any process development chemist knows, there is motivation to optimize a chemical process to produce maximum output in the minimum of reaction space. In the context of this essay, I’m referring to batch or semi-batch processes. Most multipurpose fine chemical production batch reactors have a capacity somewhere between 25 and 5000 gallons. These reactors are connected to utilities that supply heat transfer fluids for heating and cooling. These vessels are connected to inerting gases- nitrogen is typical- and to vacuum systems as well.
Maximum reactor pressure can be set as a matter of policy or by the vessel rating. Organizations can, as a matter of policy, set the maximum vessel pressure by the selection of the appropriate rupture disk rating. Vessel pressure rating and emergency venting considerations are a specialist art best left to chemical engineers.
Reactor temperatures are determined by the limits of the vessel materials and by the heat/chiller source. Batch reactors are typically heated or chilled with a heat transfer fluid. On heating, pressurized steam may be applied to the vessel jacket to provide even and controlled heating. Or a heat transfer fluid like Dowtherm may be used in a heating or chilling circuit.
Process intensification is about getting the maximum space yield (kg product per liter of reaction volume) and involves several parameters in process design. Concentration, temperature, and pressure are three of the handles the process chemist can pull to increase the reaction velocity generally, but concentration is the important variable in high space yield processes. Increasing reaction temperatures or pressures might increase the number of batches per week, but if more product per batch is desired and reactor choices are limited, then eventually the matter of higher concentration must be addressed.
The principle of the economy of scale says that on scale-up of a process, not all costs scale continuously or at the same rate. That is, if you double the scale, you double the raw material costs but not necessarily the labor costs. While there may be some beneficial economy of scale in the raw materials, most of the economy will be had in the labor component of the process cost. The labor and overhead costs in operating a full reactor are only slightly greater than a quarter full reactor. So, the labor component is diluted over a greater number of kg of product in a full reactor.
The same effect operates in higher space yield processes. The labor cost dilution effect can be considerable. This is especially important for the profitable production of commoditized products where there are many competitors and the customer makes the decision solely on price and delivery. Low margin products where raw material costs are large and relatively fixed and labor is the only cost that can be shaved are good candiates for larger scale and higher space yield.
But the chemist must be wary of certain effects when attempting process intensification. In general, process intensification involves increasing some kind of energy in the vessel. Process intensification through increased concentration will have the effect of increasing the amount of energy evolution per kilogram of reaction mixture.
Energy accumulation in a reactor is one of the most important things to consider when attempting to increase space yield. It is crucial to assure that process changes do not result in the accumulation of hazardous energy.
Energy accumulation in a reactor occurs in several ways. The accumulation of unreacted reagents is a form of stored energy. The danger here is in the potential for a runaway reaction. Accumulated reagents can react to evolve heat leading to an accelerated rates and eventually may open further exothermic pathways of decomposition. As the event ensues, the temperature rises, overwhelming the cooling capacity of the reactor. The reactor pressure rises, accelerating the event further. At some point the rupture disk bursts venting some of the reactor contents. Hopefully the pressure venting will result in cooling of the vessel contents and depressurizing the vessel. But it may not. If the pressure acceleration is greater than the deceleration afforded by the vent system, then the reactor pressure will continue to a pressure spike. This is where the weak components may fail. Hopefully, nobody is standing nearby. Survivors will report a bang followed by a rushing sound followed by a bigger bang and BLEVE-type flare if the system suffers a structural failure.
Energy accumulation can manifest in less obvious ways. Here is an example. Assume a spherical reaction volume. As the radius of the sphere increases, the surface area of the sphere increases as the square of the radius. The volume increases as the cube of the radius. So, on scale-up the volume of reaction mixture (and heat generation potential) will increase faster than the heat transfer surface area. The ratios are different for cylindrical volumes, but the principle is the same. Generally the adjustment of feed rates will take care of this matter in semi-batch reactions. Batch reactions where all of the reagents are added at once are where the unwary and unlucky can get into big trouble.
Process intensification via increased concentration may have deleterious effects on viscosity and mixing. This is especially true if slurries are produced and is even worse if a low boiling solvent is used. Slurries result in poor mixing and poor heat transfer. Low boiling solvents may be prone to cavitation with strong agitation, exacerbating the heat transfer problem. Slurry solids provide nucleation sites for the initiation of cavitation. Cavitation is difficult to detect as well. The instinct to increase agitator speed to “help” the mixing may only make matters worse by increasing the shear and thus the onset of cavitation.
Denser slurries resulting from process intensification are more problematic to transfer and filter as well. Ground gained from higher concentrations may be lost in subsequent materials handling problems. Filtration is where the whole thing can hang up. It is important for the process development chemist to pay attention to materials handling issues before commiting to increased slurry densities. Crow is best eaten while it is still warm.
Alien Fasteners. Wingnuts from space. January 3, 2010
Posted by gaussling in Bohemian, CounterCurrent, Humor, Oddities.4 comments
Imagine that you and a companion are out for an evening stroll after a big dinner, say in a park somewhere. You hear a curious whining sound and look up to see an alien spaceship on a landing approach to the park. The craft lands and the crew scuttles off to perform some tedious abduction or organ harvest in the neighborhood.
Your companion exclaims “Well! There is something you don’t see every day!”. But you’re unmoved by your companions incisive commentary. Because you see this as a long sought opportunity to examine an alien craft up close.
What would you look at? The propulsion system? Or perhaps the weapons array or guidance system? Pffft.
I would look at something much more mundane. I think it would be very enlightening to see what kind of fasteners they use. That’s right. Fasteners. Nuts, bolts, latches, bungees, straps, nails, hinges, hooks & loops, and rivets. How do these confounded exo-buggers hold things together? What’s the deal?
Fasteners are mechanical contrivances used to restrain objects into a desired configuration, often by the application and fixing of tension or compression through some structural element. Think of all of the fasteners we encounter before we set foot out the door every morning.
Elastic articles of clothing perform a fastening function through the application of tension about numerous body parts through the miracle of Spandex/Lycra. Shoe laces are fastening devices that apply and hold tension on opposing shoe upper elements wrapped over the arch of the foot.
Moving upwards, the zipper is a fastener that works in concert with a trouser/skirt button or snap fastener. The belt and buckle are a fastener ensemble that together apply and hold tension about the circumference of the waist to keep ones trousers from succumbing to the pull of gravity.
Other fasteners include shirt buttons, brassiere connectors (damn those things!), earring wires, eyeglass frames (they connect to your face), cell phone belt attachments, the deadbolt on the front door, all manner of electrical connectors, and the list goes on and on. Electrical connectors are especially interesting because they combine the functions of electrical continuity and fastener. All are a compromise between the competing interests of biomechanics, convenience, safety, regulatory standards, and custom.
So, back to the space ship. How would space faring beings approach the problem of fastening materials and components. Would they use individual components fastened together or would they use integrated component assemblies that support multiple functions? Perhaps the mechanical fastener question is moot because components would be cast, glued, or welded.
Integrated components have a certain appeal, but, by their integrated nature could serve as a node from which to initiate failure propagation to multiple systems. For instance, if a battery was built to serve as a structural element for the craft, could a battery failure of some sort serve to initiate a structural failure mode? At what point is it foolish to integrate systems rather than leave them distributed? As always, it depends.
I think an alien spacecraft would have at least a few kinds of obvious fasteners. Surely alien technologies are subject to component failures and would require occasional repair. Of interest would be the concessions to alien biomechanics.
Humans occasionally use wingnuts to fasten objects that need not be permanently affixed. The wingnut is simply a style of threaded nut that has two modest protuberances that allow for torsion and compression to be applied by the fingers and wrist. The wingnut is not functional for beings who lack the sort of articulated digits that we have. Perhaps an alien being would have a latch or other contrivance to accommodate its appendages.
Of course, all of this alien talk is just a device with which to cast the matter of fasteners into a more interesting light. Fasteners are part of our collective technological heritage and are rather under-appreciated. But, if you are unfortunate enough to be abducted by aliens, I suspect that the matter of alien fasteners might be of immediate interest.
PETN in his BVD’s December 29, 2009
Posted by gaussling in Chemistry, CounterCurrent, Current Events.2 comments
History will record an underwear bomber and a shoe bomber. Luckily for the passengers of one transatlantic flight, the anonymous martyr on board was incompetent. Like the shoe bomber before him, this murderous buffoon failed to plan for a reliable means of triggering his bomb.
PETN, or pentaerythritoltetranitrate, was found to be the explosive agent used in the attempted inflight bombing of Northwest Flight 253. This is a relatively common and powerful explosive in the category of aliphatic nitrate esters. It is a colorless powder that can be used in mixed and cast explosives or as the pure material. Like many detonable materials, it does not need to be placed in confinement to produce an explosion. PETN becomes unstable above 71 C, a fact that limits its suitability for some applications. My references do not clarify what is meant by unstable, but the material could be prone to chemical degradation above this temperature which would adversely affect its quality.
Other aliphatic nitrate esters include nitroglycerin, BTTN or 1,2,4-butanetriol trinitrate, EGDN or ethylene glycol dinitrate, and PETRIN, the trinitrate analog of PETN. A nitrate ester has a C-O-NO2 linkage and differs from aliphatic or aromatic nitro compounds which have C-NO2 linkages instead.
Nitrate esters are made from an alcohol or polyol and nitric acid. Nitro aromatics like TNT are made by acid catalyzed nitration of reasonably electron rich aromatic compounds like toluene or phenolics. The oxygen in the C-O-NO2 ester linkage confers some extra measure of instability to the molecule.
PETN is commonly used in Primacord, an explosive cord comprised of a PETN core inside a thin fabric or plastic sleeve. Primacord can be used as a blasting agent itself or it can be used as a fuse or delay line to trigger other explosives from a central point.
PETN is an explosive with a high brisance value. That is, it produces a shock that has a shattering effect on materials. In fact, brisance is quantified by the “sand test” which measures the production of fines from the shattering of 200 g of 30 mesh Ottawa sand. After the test, the sand is re-screened and the finer material that later passes through the screen is weighed. The greater the mass of fines, the greater the brisance.
Explosive Sand Crush (g) Heat of Explosion (cal/g) Black powder 8 684 Lead Azide 19 367 Comp C-4 55.7 1590 TNT 48 1080 RDX 60.2 1280 Nitroglycerin 51.5 1600 AN nil 346 Picric Acid 48.5 1000 PETN 62.7 1385 Source: Cooper & Kurowski, Introduction to the Technology of Explosives, 1996, Wiley-VCH, p76-77. ISBN 0-471-18635-XPentolite is a composition prepared from a 50/50 blend of trinitrotoluene (TNT) and PETN with wax as a bonding agent and plasticizer. There are many blends of explosive materials. The composition is adjusted for the application.
The job of an explosive is to do PV work on objects. It does this by generating an abrupt pulse of heat and a large number of small gas molecules like N2 and CO2. The detonation velocity of PETN is ~ 8 km/s, so that a relatively small number of PETN molecules in a small volume are converted rapidly into a larger number of gas phase molecules, all seeking to occupy the molar volume of 22.4 L/mol.
The prompt generation of many moles of hot, small molecules results in the expansion of decomposition gases which forcefully press against the surroundings. The gases resulting from the 8 km/s detonation wave in the bulk solid explosive expand and compress the nearby air into a shock front that expands approximately spherically. As it does this the gases cool and the shock dissipates.
Explosive Power is a measure of an explosives ability to do work. Explosive power = Q x V, Q = heat of explosion and V = volume of gas generated. The Power Index of a material is the ratio of explosive power to that of picric acid times 100 %. The power index of PETN is 167, TNT is 119, and RDX is 169.
