Good old Avogadro, he was a chemistry nerd.

[953 nut 62,170]

 

October 23 between 6.02 am and 6:02pm is Mole Day. It’s a basic chemistry algorithm, and not about those funny looking creatures called moles. It commemorates chemistry’s measuring unit called “Avogadro’s Number”. The day is celebrated as a means to bring awareness and create interest in the study of Chemistry. The day is celebrated by schools around the USA by doing mole and chemistry themed activities. In scientific terms, a mole is in relation to the molar mass of a given molecule. A mole is literally a unit of measurement to reflect an amount of a chemical substance.

 

 

[SylvanLakeWH 29,335]

A Haiku...

 

Is a mole enough

Wheel Horses in the garage?

Perhaps, perhaps not

 

 

[wh500special 2,338]

Finally, a day worth celebrating!
 

Avogadro’s number pops up at least once a week in my work for some calculation or another.  While a six with 23 zeros after it doesn’t intuitively seem like it would come in handy, it shows up in all kinds of places and in many scientific disciplines. 
 

One of my office mates is a biochemist and another is a fellow chemical engineer.  Both greeted me with “Happy Mole Day” this morning.  
 

They get me.  The rest of the place…not so much. 

 

happy mole day,
Steve

[Ed Kennell 43,101]

Moles...    Did someone say moles.   Do I need to bring the Mole Busters.

 

 

 

[Mickwhitt 5,190]

I remember our chemistry teacher valiantly trying to teach us about molar volumes and stuff. Didn't make sense then, still dudnt make sense 50 years later. 

Pounds and ounces, inches and feet, bushels, gross and fathoms I can work with, heck I can even figure in furlong and knots if I must. But MOLES? Nope, leave me outta this one.

 

[953 nut 62,170]

1 hour ago, Mickwhitt said:

Pounds and ounces, inches and feet, bushels, gross and fathoms I can work with, heck I can even figure in furlong and knots if I must. But MOLES? Nope, leave me outta this one.

Most of us never deal with things on the molecular level and quite frankly I don't miss it a bit.

[Handy Don 14,656]

I get the difficulty around 6.02x10^23. I, too, struggled with the required Chem 101 and 102 in engineering school. I passed; I celebrated by burning my textbook.

Years later a co-worker was kindly able to demystify much of what had flummoxed me with a more relevant set of explanations and its value became a lot clearer. 

This reinforced for me a great lesson I was able to call on during my work career and even now: not every teacher, or teaching method, works for every student. 

Edited October 23 by Handy Don

[wh500special 2,338]

9 hours ago, Mickwhitt said:

I remember our chemistry teacher valiantly trying to teach us about molar volumes and stuff. Didn't make sense then, still dudnt make sense 50 years later. 

Pounds and ounces, inches and feet, bushels, gross and fathoms I can work with, heck I can even figure in furlong and knots if I must. But MOLES? Nope, leave me outta this one.

 

Ah, but what kind of pounds…

 

Pound mass? 😀

Pound force? 😕

Pound moles? 🙁

 

😎
 

Steve

[dcrage 631]

6 minutes ago, wh500special said:

Ah, but what kind of pounds…

 

Pound mass? 😀

Pound force? 😕

Pound moles? 🙁

 

😎
 

Steve

Now that is a nasty expansive set of questions. Combining different units!! I’ll pass. 

[Handy Don 14,656]

18 hours ago, wh500special said:

Ah, but what kind of pounds…

 

Pound mass? 😀

Pound force? 😕

Pound moles? 🙁

 

😎
 

Steve

 

18 hours ago, dcrage said:

Now that is a nasty expansive set of questions. Combining different units!! I’ll pass. 

 

I’m thinking Pound Sterling (£) 🤣

[Ed Kennell 43,101]

19 hours ago, wh500special said:

 

Pound moles? 🙁

 

[wh500special 2,338]

54 minutes ago, Handy Don said:

 

 

I’m thinking Pound Sterling (£) 🤣

I thought of that one too.  But I figured if I got too carried away someone might tell me to pound sand. 
🤓

[wh500special 2,338]

23 hours ago, dcrage said:

Now that is a nasty expansive set of questions. Combining different units!! I’ll pass. 

All a product of us not using the metric system. 

Let’s talk about pound moles.  It will take a minute to get there…

 

Pound mass (lbm) is the analog to the kilogram as a unit of mass.  It’s what you’d get if you compared your mass to that of a known quantity.  Not easy to measure directly. Mass is an intrinsic property of something.  
 

The weight number you see on the bathroom scale is pound force (lbf).  Unless you have a scale that is a balance rather than a calibrated spring, the number on the dial reports in pounds force.  My driver’s license says I weigh 190 pounds.  That’s a lie, it should say 190 pounds force.  Well, that’s a lie too, but for another reason. 
 

nobody has such a scale.  Instead we usually just pretend 1.0 lbm = 1.0 lbf. But it’s actually off a little bit and is very dependent on where you are when you measure your weight. 
 

To convert between pounds force (weight) and pounds mass you have to divide lbf by the acceleration of gravity wherever you happen to be.  That’s generally 32.2 ft/s2 here but would be marginally less at the top of a mountain or marginally higher at the bottom of the Mariana Trench. Then to put it into useful units you multiply it by the graviational constant conversion, gc, which - not coincidentally- is also about 32.2 (32.174 lbm-ft/lbf/s2).   So lbm is usually about equal, numerically, to lbf but not identical. Sane people - of course - generally ignore the conversion.  
 

simple, right?

 

The SI system does away with this similarly-named lbm & lbf silliness.  Mass is reported in grams or kilograms.  Force in newtons.  The metric system also has a gc constant with appropriate units, but it’s numerically equal to 1.00000… so it’s universally ignored.  
 

Alas, metric system users cheat too on their bathroom scales when those scales report back in terms of kilograms.  The scale uses a spring and measures force (which would be meaured in newtons) but often converts to kg by the assumed gravity constant of 9.8 m/s2 so as to give a mass in kilograms, normalized to standard conditions.  Oof. 
 

Not everybody cheats though.

 

For things that really, really, really  matter (like in dcrage’s chemistry lab) measurements of mass are used rather than weight which is a force dependent on gravity, buoyancy, and other factors.  A gram (or lbm) is a gram is a gram anywhere in the universe.  Whereas my weight is different when measured at home versus some high elevation further from the earth’s center of gravity.  although the difference will be minor.
Lab balances - even those that measure via weight - are calibrated on-site against standard masses to align them to a constant value. 

 

Which somehow brings me to pound moles.  
 

In chemistry, physics, and related disciplines the atomic or molecular weight of something is expressed by its (surprise!) molecular weight.  

Carbon, as an example, has a rounded molecular weight of 12.  You can see that number on the Periodic Table.  Units for that are - in the SI system - 12 grams per mole.  So If you measure out 12 grams of pure carbon on a lab balance and refer to Avagadro’s number you’ll see that you have 6.02x10^23 atoms of carbon sitting there.   
 

If instead we picked something that was gaseous at standard conditions -like CO2 - and measure out a mole of it (44 grams in this case) it would take up 22.4L of volume.  Pick a different gas and measure out a mole of it and it’s always the same 22.4L.    So 2 grams of Hydrogen (H2) and 44g of CO2 take the same space but have, obviously, different mass densities (usually this is expressed as the inverse and called specific volume).   
 

The neat thing here is that you can see CO2 is 22 times more dense than hydrogen.  Hydrogen therefore floats on CO2.  Air, which is mostly nitrogen, ends up a little over 28 g/mole which is amazingly close to that of CO (deadly Carbon Monoxide) which can mean CO will spread uniformly through a home which can be disastrous.   That hydrogen powered car we worry about in a wreck?  Chances are the hydrogen would escape rapidly upward through the air and dissipate thereby minimizing the chances of a fire. 
 

Cool, huh?  Thanks Avagadro!

 

The last few paragraphs also relate to the ideal gas law of course that defines all non-reactive gases at reasonable temperatures and pressures act the same.  And it translates to reality exceptionally well (assuming you remember to use the absolute temperatures and pressures in your math). 

 

In the US we like to blend two systems of dimensions.  In addition to the SI system we have a bunch of stuff that uses the pounds, foot, BTU, etc set of dimensions in which we’ve trained ourselves to think. 
 

That Carbon atomic weight in the American system of units…it’s expressed as 12 pounds per pound mole.  Actually 12 lbm/lb-mole
 

Pound moles are sort of a niche unit used by the large scale chemical processing industry, but do show up elsewhere too.  Useful since they scale down the magnitude of numbers significantly where an engineer might be concerned about processing material in the scale of gallons, barrels, or tons rather than grams, mL, or liters. 
 

You can convert between the two moles, but it’s not generally necessary as tabulated reference data (at least here in the US) will usually be duplicated for each set of units.  So useful things like heat capacity, Gibbs free energy, enthalpy, etc will be tabulated in both sets of units to match up to whether you want to see how much heat (joules) will be sucked up when 100g of salt is dissolved in water or how much energy (BTU) will be liberated when a half a pound of octane is burned. 
 

The analogs in the different systems of units sometimes seem arbitrary, but not all of them actually are.  Heat is a good example. A calorie is the amount of heat needed to raise the temperature of one gram of liquid water one degree Celsius.  The BTU (another thing we should thank the Brits for) is the heat needed to raise the temperature of one pound of water one degree Fahrenheit.  
 

Real calories and dietitian calories are different by the way.  That 100 calorie snack really contains 100000 heat calories. They lopped off a few orders of magnitude to make the numbers more convenient. 

 

How’s that for prolix trivia for the day?

it’s sort of a shame that we learn about all this stuff at a phase in our lives where it doesn’t seem the least bit interesting to

most of us.  I think that can apply to any topic as our interests evolve over time and the opportunities we had to learn when young just aren’t there when older.  

 

Steve

Edited October 25 by wh500special
Spelling

[Handy Don 14,656]

45 minutes ago, wh500special said:

it’s sort of a shame that we learn about all this stuff at a phase in our lives where it doesn’t seem the least bit interesting to most of us

I agree. At college, for us non-ChemEs, there seemed to be all but no applicability. It was later, while working with nuclear engineers on real world reactors, that the concepts gelled for me. 

And it isn’t just H.S. and undergrad stuff. In U.S. medical school curricula lab anatomy (i.e. with cadavers) is usually a second year course with organic chemistry and biology stuff filling the first year. In Ireland, anatomy starts on Day One and continues through all three years with all other courses reinforced via anatomy. 

[wh500special 2,338]

I can relate.  In college I took virtually no interest in EE stuff.  Not so much a lack of the capability to understand and I didn’t have any trouble getting through my required minimal introduction, but just not particularly curious about what they studied.  Then to find out that they actually USE imaginary numbers in their math and i cemented my attitude that it wasn’t for me. I’d never use it…
 

Huge missed opportunity. 
 

25+ years into this gig, my responsibilities at work have drifted into electrical projects.  Our primary EE developed health problems and suddenly retired about the same time we really needed his expertise.  The young guys seemed to lack any real understanding of what we were trying to accomplish and the tight timelines meant I had to get out the books so I could be conversant with and keep honest the outside firm I’d hired to do our electronics designs.  It also doesn’t help that they (young guys) only wanted to focus on the software aspects of things and are all too keen to ask Ai how to do something rather than give it any thought of their own. 
 

Anyway…
 

I don’t know what happens to a brain over time, but this time around not only was the material interesting but it was - for unknown reasons - much easier to absorb and understand.   I’m generally perspicacious, but transient electrical concepts eluded me the first time through but now it seems easier.  
 

Who knows why, but there’s no doubt that things gel later in life. Whatever it is, I think our innate learning timeline isn’t quite aligned with our educational opportunities.  But again, there’s only so much time…

 

You mentioned anatomy…

 

My wife is a doctor.  I don’t remember what year in med school she had anatomy, but second year sounds about right.  She liked it well enough and has indicated it was incredibly interesting, but she had no interest in being a surgeon.  While a major part of her training, it likely didn’t rank at the top of the list as key in the treatment of her patients as other parts of her training were probably more prominent in her specialty. 
 

I think at the age (24-25) when they take anatomy, the students have matured enough to appreciate the need to be thorough and complete even if they’re not going to be cutters in their career track. So they take it seriously and treat it as a fundamental building block.
 

Maybe coincidentally, I think that’s the same age where the typical brain finally develops sound decision making and impulse control.  Before that, we’re all impulsive animals.  This probably goes back to the initial point about missed opportunities. 
 

It’s hard to think of it this way, but even med school is a gateway and requires a wide range of things to be covered.  Chemistry, pharmacology, biochemistry, virology, psychology, plus all the individual treatment specialities…they cover a huge breadth because the graduates will fan out over countless disciplines where their education will continue.

 

As an aside, we’re old enough that she went through that system when it was still quite brutal.  I wouldn’t believe how little sleep those new doctors run on if I’d hadn’t witnessed it myself.  To this day, I still feel guilty if I feel tired after a long day at work as I remember she’d clock more hours on her feet without sleep in two days than most people will do in an entire work week.  All while running the brain at 100% and not taking any breaks. 48 hours straight was the norm…and I mean straight through with no more than an occasional pause to eat a candy bar or use the bathroom (probably at the same time🤢). 

And that went on relentlessly for the better part of three years.  The point of all of that was to make medicine automatic.  And it worked.

 

I guess given enough time, anything can become automatic. 

[Handy Don 14,656]

I began college thinking it’d be fun but not really a lot to learn. After five years (the extra year and two summers due to a change in major), and eventually being on the dean’s list, I graduated thinking I knew so little, no one would hire me. Five years getting dumber? Of course not. Five years realizing how much there was (is!) to know. 

I concur that higher ed--college and grad school--when at their best both broaden and deepen one's store of knowledge. And, as I remind young folks, it simultaneously begins to narrow some future options. Not from inability or disinterest, but from infinite information vs. finite time. This is not a bad thing; it is just something to understand. 

I also concur heartily that when faced with a “need/want to know” our brains really can absorb a lot even into much later years. I’ve noted in earlier posts that partial diff equations stumped me in college (part of why I left engineering to become a quant) but snapped into clarity about twenty years later!

I recently witnessed a team of medical professionals as they addressed a condition with highly unusual presentation. Despite all the “best practice" tests, scans, scopes, expert consultations, and medications, a definitive diagnosis remained elusive. Eventually, they pooled knowledge and experience to reach consensus on a "most probably” and went from there. IMO, no textbook or machine learning could have done this (at least for the next few years).