Measuring Density with Pycnometers, Hydrometers, and Graduated Cylinders 

I am a retired analytical chemist. One mistake I noted was the lack of gloves when handling analytical glassware. Finger prints have mass and will change resuls in the second to the third decimal place depending on cleanliness of hands. Also, non-conducting liquids will suffer from static charges so an anti-static device is recommended. Otherwise your chemistry is excellent as ever Dr. Nurdrage!

Non physical things such as minds, which can be exceptionally dense. Solid gold.

The flask grinding part was something I had heard about but I hadn't seen anyone actually do it - super useful

I’m definitely a fan of flashy synthetic chemistry stuff, but I really appreciate the analytical deep dives. I always learn something new and analytical chemistry is in the “how the sausage gets made” territory of chemistry. Dreadfully unsexy but damned useful. Thank you for years of contributions to the science!

I am not any sort of chemist but I still find this kind of stuff super interesting. It's about human ingenuity and how people figured out interesting ways to solve problems and that is always interesting at least to me. I will probably never need to know how to do any of this but I like knowing it anyway.

Nurd Rage keep up these videos, one of the most credible sources of chemical techniques on RU-vid and an added bonus you are a fellow Canadian!

Lovely video. These are great for ideas. A university auctioned off a gas type powder density instrument that I had my eye on for the nice vacuum pump, obviously others had a greater need and it went for a more reasonable price around EUR1000. One great inline accessory for distillation is the parrot, it allows for continuous measurement of temperature and density of the distillate with a hygrometer and thermometer in a bottom fed overflowing cylinder.

I'm not a chemist, and I often get lazy/suck at calculating everything, but you've given me several ideas for how to finally determine the purity of my homemade KCl fertilizer. In short, I used temperature solubility distillation to purify low sodium table salt (30% NaCl to 70% KCl) that I got for almost free, and while I assume I got it to around 90% pure, I don't actually have any data to back that up. All I did was dissolve as much salt as possible in boiling water (so around 97c where I live) and then cooled that solution down to as close to freezing as possible (around -20c). In theory, most of what precipitated out should have been KCl, but I've had no way of actually determining that analytically and didn't really care enough to figure it out on my own. Now that your video's gone through all the details of how to accurately determine the density of a salt (both as a solution and powder, though I assume powder would be easier in my case?), I should have everything I'd need to figure out how pure my sample is just by throwing the observed density into this simple formula densityOfNaCl*(1-concentration) + densityOfKCl*(concentration) = observedDensity with concentration being what I'm after.

There is no good reason for me to watch this but I did. I feel smarter, though not in a way that is useful for my practical day to day life experience. I do not feel that my time has been wasted.

The shade in the phrase “humans are very dense” is pitch black lmao 😂

a shortcut to remove/reduce the reading errors on glassware. use two lines (i.e. 50 and 100) and use the surface curvature for exact positioning, i.e. in both cases the bottom of the surface bulge just barely touches the top of the line. this way it is slightly more accurate. though temperature must always be factored in! bonus tip: if you work in a lab, use the "big names" as they dont cheap out on proper markings. very cheap stuff is off, most of the times..

I once bought a graduated cylinder that was off by so much I started wondering if the scale was in milli-quarts. Moral of the story, always verify your equipment.

Anton Paar has been selling cheap u-tube hydrometers since at least 2014. That's when i got one for battery acid testing.

Ok, when showing the basics of finding density. Is there a reason you weighed the cylinder, added water, and weighed it again instead of putting the cylinder on the scale, zeroing it, and then adding water so you start off with only the weight of the water?

Very cool!

i need to stop watching news from UA... i was reading "Pycnometer" as "Rusnometer" 🤣

You know the priorities of a species when the measuring tool scales on beverages...

Could any vessel do as a pycnometer if results could be replaced reliably? Seems like something like that could be easily replicated, any flask with a 3d printed stopper could provide similar results?

Since the density can be affected by atmospheric pressure and earth gravity consider the compressibility of the material and your local deviation from standard gravity g within 0.6%. Caused mostly by latitude and local earth crust density. There is also a tidal force of moon 1.1 × 10^−7 g and sun 0.52 × 10^−7 g. The effects of jupiter and smaller planets may be neglected since they are lost in the measurement noise and are beyond precision of international standard kilogram.

The vacuum method seems overly difficult. If you used gas pressure and added gas to a known size vessel, you could then pressurize it to 2 atmospheres. Then measure the amount of gas that escapes.

More analytical slander... classical analytical chemistry is the most "science" the average chemist will do and novel analytical chemistry is quite sexy!

When you started mentioning the "U-Tube density meter" I started thinking that youtube had some means of measuring the density of human minds.

As a non-chemist, I sometimes find these videos more interesting than your others. It feels like I'm legit learning something rather than watching a magic trick.

Ok but how can I scientifically measure if someone is _Thicc_

*Summary* *Basic Density Measurement* * *(**1:20**) Graduated cylinders* are a simple but not very accurate way to measure liquid density. * Weigh the empty cylinder, add liquid, weigh again, and divide the mass difference by the volume reading. * Errors can arise from temperature differences and meniscus readings. *Specialized Tools and Techniques* * *(**2:47**) Hydrometers* are inexpensive floaters that directly indicate density on a calibrated scale. * Easy to use, just float in the liquid and read the scale. * Great for quick checks, like monitoring home brewing or electrolyte concentration. * Limited measurement range (often 1-1.2 g/mL), not suitable for all liquids. * *(**5:04**) Pycnometers* are precise volumetric flasks with a capillary hole in the stopper to ensure a reproducible volume. * Calibrate by weighing empty, then filled with a liquid of known density (usually water). * Fill with the unknown liquid, weigh, and calculate density using the calibrated volume. * Much more accurate than graduated cylinders and hydrometers. * Affordable for amateurs, with professional models offering even greater precision. * *(**9:14**) Grinding Pycnometer Stoppers* * Cheap pycnometers may have wobbly stoppers that can be improved by grinding. * Use valve grinding compound and a hand drill (with caution!) for a tighter fit. * Not strictly necessary for amateur use, but improves accuracy for perfectionists. *Measuring Solid Density* * *(**14:34**) Archimedes' Principle:* A submerged object experiences an upward force equal to the weight of the displaced liquid. * Weigh the solid, then submerge it in a liquid of known density (water is common). * Measure the weight difference to calculate the volume of liquid displaced, which equals the solid's volume. * Divide the solid's mass by its volume to determine density. * *(**17:17**) Powder Density with a Pycnometer:* * Calibrate the pycnometer as usual. * Choose a solvent that the powder doesn't dissolve (or has very low solubility) in. * Create a saturated solution of the powder in the solvent. * Fill the pycnometer with the powder, then add the saturated solvent to fill the gaps. * Carefully remove air bubbles. * Measure the mass of the powder + solvent, subtract the known mass of the powder, and use the solvent's density to calculate its volume. * Subtract the solvent volume from the pycnometer's total volume to find the powder's volume. * Divide the powder's mass by its volume to get its density. *Professional Density Measurement* * *(**12:37**) U-tube density meters* are digital instruments that use vibration to precisely measure liquid density. * Fast and accurate, but expensive. * Now available for amateur use, but with limited density range (mostly for brewing). * *(**21:39**) Gas pycnometers* use gas displacement to measure the volume of powders, even porous ones. * Accurate and versatile, but expensive. *General Tips* * Use a companion weight (11:49) to simplify mass measurements with a pycnometer. * When measuring powder density, choose a solvent with low solubility in the powder. * Saturate the chosen solvent with the powder to minimize errors due to dissolution. The video emphasizes that while density measurement might not be the most glamorous aspect of chemistry, it's a fundamental and valuable technique for characterizing substances and monitoring reactions. i used gemini 1.5 pro to summarize the transcript

As one who also enjoys maker channels, I couldn’t help but think when seeing the gas pycnometer and U tube device, “those are things that a lot of folks could make themselves if push came to shove.”

The mass of RU-vid and the density are off the charts

That's basically what is the topic of a practical exam I need to take in a few weeks to become a chemical lab assistant. Love my job but the pycnometer makes me wanna end myself sometimes.

This is one of my favorite videos that you ever made and i have been watching since the beginning

genuinely excited to learn dude this is a topic i havent ever given much thought to thank you for the lesson :D

One of my friend's mom had a bunch of volumetric flasks she was using for decoration. When she found out I was into chem, she gave them to me! That was over 20 years ago and I still have them. They were always my goto when I needed to find the density of something. Those great quality flasks probable cost more than all my cheap chineseum glassware I own! I don't really know what brands are God tier with labware, but I just looked up the 25ml Kimax class "A" volumetric flask and a 6 pack sells for $290! So thats like 50 bucks for 1! Also looking at the specs, the one I have is even better. The ones online are +-0.08ml, while the one I have is +- 0.03ml.

You forgot to mention when measuring density with water displacement, you must yell, "Eureka!" after checking the level.

This video is amazing, please post more. I'm watching this on repeat in support. Please don't watch my content till later.

I wondered how to improve the seal on some antique storage jars and never thought to use valve grinding compound. Thanks for the tip. Beats trying to find cerium oxide lens grinding compound.

I think a drill press, that's been squared up well, would have worked a lot better. You introduced a lot of human error/influence on the grind. Because you were not able to keep the exact same axis when grinding. You could have had it perfect at one point then kept going off axis and made it worse.

i could imagine that density of the crown being incorrect due to a trapped bubble but thats non of my business lol

Have a ridiculously awesome day

An entire series on metrology in chemistry would be nice. Especially the "this is good enough for home amateurs" observations. I personally tend to stress WAAAY too much over precision in calculations, despite not having the means to measure at the numbers of digits I'm fussing over.

I got some pyc's and hydro's a while back to to test some solution concentrations - never got around to it. OK, I got the bug again. Good info on re-grinding the stoppers. Cheers, MarkBee

You know you constantly rag on analytical chemistry but I'm making a pretty good living "flipping burgers” Thank you.

I really liked the animations and visualizations in this video!

This is totally super awesome!!! THANK YOU!!! \(^_^)/

But why is it not Pyk? or Puk? Pycnometer makes me start reading it as Cyrillic every time.

Its kinda crazy how much ive learned watching your channel for the past 14 years since i was a freshman in highschool, i wound up just doing HVAC lol. I still have a nice collection of mixed gold ive been piling up to turn into pure gold, im just waiting until i decide to invest in the proper equipment and build a ventilation hood.

Dude your stuff just engrosses me... I don't know if it's your pleasant-soothing voice, or if it's the content and how I always learn something neat. regardless, it's great seeing you post again! You ever try those electric canned air thingies?? I have a few of them, and they totally rock if I ever need to blow away some water off a surface (or a load of other reasons).

This is super useful even for the amateur. Sure you can make something, but how do you know exactly what youve made? These techniques exist because without reliable information youre flying blind. I also love the amateur oriented creativity of grinding the pycnometer joint. Sure maybe most amateur scales are less accurate anyway, but thats no reason to add error if it can be easily avoided. Besides, this way if you upgrade to a really nice scale you wont have to buy new glassware.

If you are going to use a drill for glass grinding, don't chuck the glass directly into the jaws of the drill. Use a bolt or other metal rod and connect it to the glass with a piece of rubber hose to use as a flexible joint. This is how we grind engine valves without removing a cylinder head. We don't want any damage on the valve stem!

Electrical engineer working in chemical manufacturing - we use coriolis flow meters for accurate massflow (e.g. custody transfer), they work the same way as the U tube density meters

I'm up for all the basics you want to share.

Your story about measuring 500 samples is a textbook case calling for a programmable calculator. No need for companion mass. It also stores it for you if you program it right.

It really feels like a U-tube density meter should be relatively easy to cobble together for just tens of dollars. I think a tube with a magnet glued to it and a coil with some even breadboard level electronics would be sufficient. It would probably take longer to calibrate than actually build. I don't see why it couldn't or shouldn't be made of borosilicate instead of some kind of metal either. I think it should also work for gasses.

It looks like it would be easy to make your own Hydrometer. You could probably trim an existing one by adding weight.

So from my understanding archemedes took the crown and put it on a scale. Then he balanced the scale with an amount of known pure gold. Then he submerged both sides of the scale in two identical volumetric cylinders with equal amounts of water. Then the gold side displaced slightly less water than the crown side, revealing the scam.

Clicked purely as I work as a technician and found a bunch of pycnometers, didn't have the slightest clue as to how they are used. Highly suspect they'll never be used again, but at least I can label them up so anyone after me knows what they are.

I'm not a chemist by trade, and I found this fascinating. Not sure if I have the steady hands to do 500 density measurements in an hour, though...

Hey there! Would you teach us how to make a metal-organic gas sieve/separator catalysis?

Make a video of electrolysis of Na2CO3 or Na2HCO3.

I especially loved the hidden dimensions of the well known story of Archimedes.

there are high-precision hydrometers as well! i worked with some that were "accurate" to 3 digits and technically the fouth was imaginable between the lines. (i.e. 1.003 / 1.0035). and for most situations they were scarily accurate! We mostly used pygnometers for density measurements of solids and mostly in training. after that its digital. they are practically as fast or faster and far more precise. :D

EDTA is also a very common anticoagulant used in laboratory analysis of blood!

Apparently Ive been performing the Archimedes method wrong my entire life

"The goldsmith was pleased with no longer needing haircuts for the rest of his life." 😂

Very much appreciate deep dives into the shallow end of the chemistry pool! 😂 It is good to have a reminder that even the most trivial elements can have great meaning and impact. 😊 Thank you, Dr. Nurdrage! 🧪

fun fact: if you want to know the density of a person you only need to ask them if 1 kilo of feathers is lighter than 1 kilo of lead.

So many mentions of RU-vid in this U-Tube…

Happy to learn the aliens didn't ... gulp

Just a question: why not use the tare function of the scale?

There's no such thing as " colder " 😆

A note on the saturated solution part (propably only applicable to way higher precision measuring than amateur with most solid/solvent combos). I worked for a while with people that were measuring the solubilities of stuff to extreme precision and i learned that a lot of solutions will take an extremely long time to actually reach saturation, from a few days to weeks or even months if i recall correctly. But the change in the dissolved content slows way down pretty quick so propably no need to wait for weeks 😅

watching u-tube videos on youtube

I worked on the design of a Coriolis massflowmeter for my doctoral work - that's a few steps more complex than a "U-tube densitometer". Would the amateur-chemistry enthusiasts be interested in "instructables" style notes on how to build one? (the densitometer, I mean..)

Burger flipping... Not funny

1:14 you got me good with that one. Congrats !

so interesting! but doesnt even the gas method have limitations? how does the system handle powders that sublimate as the vacuum stage ramps up? I feel like nothing in analytical has an ultimate method regardless of costs

I read it Руспоmeter

Non-scientific person here but is there a reason why you don't use the tear button to zero out the scale after you measure the empty flask?

Now how do we measure how dense a politician is? :P

Thank you! This is so useful! Without knowing what I was doing I sorta fumbled my way through using a liquid that doesn't dissolve the various powder I was trying to measure. Pycnometers now added to my list of things I need to get.

I also used to get irritated when employers would ask me to evaluate tedious things. Once I was asked to evaluate several thermal interface materials for their performance, and vocally griped about it to my boss. I later realized how utterly fascinating all of this was. It's just how it goes in science sometimes. Thanks for the great content!

When you were talking about the cap wobbling in the bottle I was thinking, hey you could lap the cap and bottle with valve lapping compound. And then you did exactly that!

Super cool video, I love it. I am not a chemist (or a computational one either), but find the methods you presented fascinating to know. Maybe I will never need to use this knowledge you shared here, but I still really love to know it.

You can't scare me away with the threat of boring chemistry! Jokes on you...that's what I'm here for! 🤓

In the first part of the video you used a cylinder. Is there any reason why you didn't use a volumetric flask instead? Is a class A volunetric flask just as inaccurate as a cylinder?

Thanks for this one! I learnt something today. I never knew there were any other kind of pycnometer than the helium electronic ones I am used to.

Hey! You got something slightly wrong about the u-tube density measurement thigny. Not only does the frequency changes, there is also a gyroscopic effect that twists the u perpendicular to the oscillation axis. The device likely measures the force produced from that twist for the most accuracy. The liquid moving in a semi-circle at the bottom of the U acts as a turning flywheel that resists the oscillation and induces the gyroscopic effect.

i rediscovered infomation from this video i had learned and forgotten to time thank you for the lesson i learned alot :)

density is given in g/cc forget ml

thanks!

Sensors are cool. Just not the internet type.

Amazing video!!

Outstanding!!

Fantastic!!!