Pycnometers Made Easy--The Best Way to Measure Density! By Dr. Shawn

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In this video renowned educator Dr. Shawn* explains, in the simplest possible way, pycnometers and how to use them to accurately and precisely measure density. Intended for STEM teachers, citizen scientists, and students.
To help you secure the tools you'll need to do this and other projects, we recommend www.LabSuppliesUSA.com. We get a lot of our science supplies there. They are good people who cater to citizen scientists and educators and offer some of the lowest prices online.
Pycnometer:
labsuppliesusa.com/product/sp...
Digital Scale:
labsuppliesusa.com/product/ps...
*Shawn Carlson holds a Ph.D. in nuclear physics from UC Los Angeles. He is the founder of the Society for Amateur Scientists, LabRats Science Education Program, and Engagement Education. His work has been featured in numerous national publications. He is a former columnist for Scientific American and Make magazines, and a winner of the MacArthur "genius" Prize for his innovative approaches to inspiring people to love learning STEM. See: www.macfound.org/fellows/604/ and en.wikipedia.org/wiki/Shawn_C...
This video is sponsored by the LabRats Science Education Program: www.LabRats.org

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4 апр 2018

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Комментарии : 121

@AnthonyFrancisJones 2 года назад

Excellent explanation. I have used the old ones that were hidden away in a dusty cupboard for years with young students and they enjoyed both the understanding of density and comparisons of distilled and salt water.

@MinaiUsagi 4 года назад

christ, THIS IS SO EASY TO UNDERSTAND! All my school materials make it more complicated than necessary! Thank you very much for the video!

@Totalscience569 4 года назад

Chemist, thank you so much for this video because tomorrow is my oral test about this topic... And now able to given my ans and perform the practical carefully.... God bless you sir..

@alexhannon9467 4 года назад

This is presented with beautiful clarity. Two different values are given for the density of water at 23 centigrade, and I think the right value is 0.99753 g/cc.

@nurbanuyanar5479 3 года назад

That is such a creative video! Fun to watch, and I understand it very well. Thanks!

@brunovelasque8951 Год назад

Wow this video is super helpful! You explained the subject well in a short and concise manner. Thank you so much!

@grahamwilson8843 Год назад

I really appreciate that you made this! A perfect way to know what I'm doing going into the density lab in chemistry class. Thanks!

@omarino99 5 лет назад

This video is perfectly clear. Congrats and thank you

@sreylensaing182 4 года назад

This video is very helpful for Food Science and Technology students like me. Thanks! Please keep producing more videos.

@hulinwei5915 2 года назад

very very easy to understand! Thank you for sharing this video!

@denniswhv7546 3 года назад

Thanks for teaching me this unit in ~9 mins, You helped me out here. Greets from Germany.

@citizenscientistsworkshop1948 3 года назад

My pleasure! I hope you subscribed to my channel.

@johnmiller0000 4 года назад

Very clear - thank you. I'd love to see this done in Imperial units just for the pain of it.

@kamalakarpullamraj7256 4 года назад

thank you Mr.Carlson

@tristanchristensen5963 4 года назад

Great job explaining! Time to kick ass tomorrow at lab

@isaacblep9875 4 года назад

Just perfect! thanks from Panamá

@mdatiqurrahman9951 6 месяцев назад

Incredible explanation- must appreciate that. 🤗

@dellainesrine3197 4 года назад

thank you, sir, this video helped me a lot.

@achalawithanage7141 2 года назад

Thank you,great explanation✨️

@NuwanPushpakumara-jn6qq Год назад

Thank for lesson, it's really help for me

@virendrasrivastava2702 5 лет назад

Done exactly same as written in my physics book Perfection😲😲😲😲

@rokayamouada1474 3 года назад

So clear thank you

@sailormoonz9896 5 лет назад

PERFECTION!!!!!

@joecooper3073 5 лет назад

This video helped me so much, thank you!

@citizenscientistsworkshop1948 5 лет назад

I'm so glad to hear it. You made my afternoon.

@MarkGoren 4 года назад

This is so good thx so much

@manojkumar-re2ye 5 лет назад

Amazed Looking for more videos

@gholamrezabonyadi5572 3 года назад

Perfect. Thanks

@madhusudhanreddy1510 6 лет назад

very good explanation

@ramaos8542 4 года назад

You're a life saver

@anikislam8507 4 года назад

awesome. thanks from Bangladesh

@aalkhasha2023 4 года назад

ThanQ very much

@devirajamanththri8003 3 года назад

Thank you sir

@user-df5is8jy6n 3 года назад

thanks for the superb explanation. how accurate this method for porous material such as activated carbon? and what kind of density do I obtain? bulk density, apparent density or true density?

@aalkhasha2023 4 года назад

I am Arafat alKhasha from Yemen. I have PhD in Soil Science from King Saud University last April. I am looking for a job, thank you.

@tomuranokatze6598 5 лет назад

danke vielmals

@ethioupdatedinfo. 3 года назад

Very helpful!thanks

@citizenscientistsworkshop1948 3 года назад

Glad it was helpful!

@esraipekci9467 3 года назад

Thank you 😊

@citizenscientistsworkshop1948 3 года назад

You're welcome 😊

@wessonsmithjr.6257 5 лет назад

FYI if you need to measure something that dissolves in H2O but not ethanol use ethanol as the medium instead. Just need to know the density of the ethanol first. I suppose you can use any liquid once you know it's density.

@citizenscientistsworkshop1948 5 лет назад

You are of course correct. Thanks for the input!

@zillurrahman2706 2 месяца назад

How can I get the density of powdered particles? Thanks for the video, it is very helpful.

@marioperezcortes500 6 лет назад

Good

@kudakwashechenjerai3540 4 года назад

what method can be used to measure grains

@gabrielawandut9901 11 месяцев назад

Would it be possible to activate subtitles on occasion? Thank you

@jerilyncruz5069 4 года назад

Thank you very much for the video! It really helped me a lot. I do have a question. What if my liquid sample (acetone) is not enough for the pycnometer?

@citizenscientistsworkshop1948 4 года назад

Jerilyn Cruz : Interesting question. If you don’t have enough sample to fill your pycnometer you either need more sample or a smaller pycnometer. Now, you could always create a smaller pycnometer by adding a chemically inert solid inside which will reduce the volume and increase the mass. Then recalibrate taking the mass of the instrument to be (glass + solid) and the volume to be the reduced volume, which you measure using distilled water exactly as shown in the video. So, for example, reduce the volume by adding steel BBs until it’s small enough for your sample. Next, recalibrate for the new mass and volume and then thoroughly dry everything to remove all of the distilled water. Then measure the density of your sample. I hope that helps you. Let me know if you have any other questions.

@WhiteScienceCommunity 2 года назад

شرح ممتاز

@JunkoMay 4 года назад

is there any standard density for toothpaste ?

@benwalsh8943 4 года назад

Isn't density also dependent on temperature and barometric pressure? Your description is great for a basic understanding, but in most laboratories they either use a digital density meter or equilibriate the temperature of full pycnometer in a water bath. I would call a pycnometer a very economic way of measuring density but it is not the most accurate. Best is subjective in this case and probably should not be used. I do thank you for a very well produced video and only add comment to contribute and not criticize.

@citizenscientistsworkshop1948 4 года назад

Ben Walsh : Thanks for your comment. Pycnometers make it easy to accurately and precisely measure density. The precision is not limited by the technique, but rather by your ability to determine and mass and volume of the instrument. I’m using a very simple and low cost digital scale. If one were to instead use a precision scale that determined mass to say one part in 100,000 then one works need to control for temperature and the buoyant force on the atmosphere. But pycnometers are also used in these applications as well. The precision and accuracy is not limited by the technique, it’s limited by the precision and accuracy of the scale, and the purity of the water used for calibration.

@ritusingh6163 5 лет назад

Please aoac table Ka link send kar de..

@pavan3187 Месяц назад

Please show the calculation part

@anshumanyadav2388 6 лет назад

nice

@abodo12980 5 лет назад

Hi the video is excellent i would like to ask if you have the method in PDF thank you very much A

@citizenscientistsworkshop1948 5 лет назад

I'm very sorry, but I don't have this in a PDF format.

@sinsrow8975 6 лет назад

It's Trivial to Nitpick. Very Informative nevertheless

@melilianabudiwati2372 5 лет назад

Hi can you teach how to determine what chemical in compound pvc?

@mixing-pu8fe 4 года назад

hevac you

@Jigoday 4 года назад

Bhut a66a tha video

@TheJah1985 4 года назад

OK it perfectly describes how a pycnometer works, but to be really precise, you have to use a way more sensitive scale and must consider the density of the air, that was in the pycnometer as you calibrated it

@citizenscientistsworkshop1948 4 года назад

Yes, you are right. But this video was made to support students and citizen scientists and help them to understand the method. I don’t have such accurate equipment in my home lab. Maybe I’ll do a follow up video at a later time. Thanks for commenting.

@muhammadim1575 6 лет назад

very informative ...could i measure the density of fat (solid) by this method ?

@anthonyfeng6180 5 лет назад

and very helpful for a university student ... we can measure the density of fat (solid) by this method

@user-tp1co2yg2f 9 месяцев назад

In my book

@justmdylan 9 месяцев назад

In my book au cas où

@kagwangkah2153 3 года назад

at 3:47 where did the density of the distilled water come from? pls i need an immediate answer. thanks!

@citizenscientistsworkshop1948 3 года назад

The gram was DEFINED so that the density of distilled water at 4.0 degrees C would be exactly 1.0000 grams / cm^3.

@user-su1dk8et2l 10 месяцев назад

I have a question: When determining the exact volume of the pycnometer, if it is filled with deionized water and contains several air bubbles inside, what impact will this error have on the determination of the mass density of solutions with known concentrations? Will the mass densities be overestimated, underestimated, or does the error have no impact on the determination of the mass density of the solutions? Thank you!

@citizenscientistsworkshop1948 10 месяцев назад

The air bubbles will displace water. Therefore the weight of the water used in the calibration will be be too small. This will cause you to underestimate the volume of the flask and therefore overestimate the density of whatever you measure.

@reza2629 4 года назад

is it okay to hold the pycno by bare hand? not only glove even covering-tissue? thanks for the video before Sir

@citizenscientistsworkshop1948 4 года назад

restu andreza : Yes, under most circumstances. The mass of any fingerprints is far too low to affect the measurements in all but the most sensitive experiments. And any heat transferred through the liquid by handling the glassware is too small to make a measurable difference on the outcome.

@reza2629 4 года назад

@@citizenscientistsworkshop1948 thank you for answering Sir. Best regard-

@jmhannnon 6 лет назад

Interesting, a gadget I was not aware of the name for. Your comments about the grades of steel is a bit confusing. I did a bit of looking and there does not seem to a straight forward relationship between the type of steel and its density. A low carbon steel would be more dense than a high carbon steel because carbon is less dense than iron. A high carbon steel could be considered a higher grade because it is generally stronger. Densities of tool steels are all over the map with each type having specific properties rather than one being a higher or lower grade.

@citizenscientistsworkshop1948 6 лет назад

Hi Jim, thanks for pointing this out about steel. You're quite right. I appreciate the correction.

@sayad3133 2 года назад

Hello professor Is it possible to increase the density of mercury?

@citizenscientistsworkshop1948 2 года назад

No. Density is an intrinsic property of a substance. It can not be changed.

@36MSERIAS 5 лет назад

Why are the volume of measured water are way off? And how do you calculate the volume of pycnometer?

@citizenscientistsworkshop1948 5 лет назад

I can't explain why the volume on the bottle is completely inconsistent with the measured value. You'd have to ask the manufacturer. However, as I show in the video, to calculate the volume to fill the pycnometer with distilled water and weight the instrument. Then you find the weight of the water by subtracting the weight of the instrument dry from the combined weight of the instrument + water. Since distilled water has a known density at room temperature (value given in the video) you divide the mass of the water by the density of the water and find the value of the water, which, since it completely fills the instrument, will also be the volume of the pycnometer. Please watch the video again for all the details.

@citizenscientistsworkshop1948 5 лет назад

@@angelatampubolon8442 I knew it. The density of distilled water is a well known function of temperature. I took the value of the density of distilled water at the temperature of my laboratory from a table of densities vs temperature.

@joeschmoe3815 5 лет назад

@@citizenscientistsworkshop1948 You have to order your pycnometers pre calibrated. Then they engrave the volume on the glass wall. Also, do not dab the capillary on the top with paper. This leads to false measurements. Use a syringe needle to scrape away the excess liquid. The dab around the hole with paper. Sources: lab technician. I do this 50 times per week.

@krishnendugiri7077 5 лет назад

How do we calculate pycnometer error???

@citizenscientistsworkshop1948 5 лет назад

Great question. The simplest way is to repeat density measurements for the same sample material and calculate the observed variance in your answer. Rule of thumb is that you want to do this 30 times to get a good estimate. If you really need the error to be below a certain value then you need the enough data to be able to measure the variance of the variance to confirm whether the instrument is accurate enough for your work. But if this instrument isn’t accurate enough ... you’d be working at a level beyond what I’ve ever required in my research.

@firesurfer Год назад

Ummm, a side note, can the density of gold be faked? That is, using a perfect combination of gold and tungsten to create the equivalent of gold. possibly with hollow spaces inside to match volume? I think in theory, to get a perfect calculation, the particular item would need to be melted down to eliminate spaces.

@citizenscientistsworkshop1948 Год назад

Sure, in principle. But then the expansion coefficient, the reflectivity, the resistivity, thermal conductance and other properties wouldn’t match. There is no way to fake a material’s easy to measure properties at the same time.

@AJ-uo8tk 4 года назад

Is it possible to dissolve 1g powder into distilled water and measure the powder's density using this method?

@citizenscientistsworkshop1948 4 года назад

No. The density of a dry solid can not be determined from the density a solute into which it is dissolved. The density of the solid depends on the physical arrangement of the molecules in the lattice. That information is lost when the solid dissolves.

@AJ-uo8tk 4 года назад

@@citizenscientistsworkshop1948 Thank you for the reply! I believe it is possible with a gas pycnometer but we don't have one in my University unfortunately.

@AlfredIsac 3 года назад

Man, Great Explanation. But needed one more help please.... How to find the alcohol content in a wine? The issue I'm facing is that because of the presence of unknown particles the density of wine is showing more than 1, the density of water(which is like no alcohol). But surely there is alcohol in the wine. How to solve the issue? To take the density of wine before fermentation instead of water? If so, how to do the calculation?

@citizenscientistsworkshop1948 3 года назад

Can you first filter the wine? Or allow the particles to settle out and then decant the liquid?

@AlfredIsac 3 года назад

@@citizenscientistsworkshop1948 I've filtered and settled out. By particles I mean invisible particles. The wine is crystal clear with its color. I think what causing the density to be more than 1 is particles that give color, unfermented sugar if any, and nutrients or minerals. Don't know.

@citizenscientistsworkshop1948 3 года назад

@@AlfredIsac : You may be right. The density of wort or mash before fermentation is always greater than one. As fermentation progresses the density drops, but it needn't drop below 1.00. If you were expecting the final density to be less that this, then your fermentation may have gotten stuck because they yeast were missing an essential nutrient. I can't tell you why your results are not satisfactory. Did you use a pycnometer or hygrometer to make your measurement?

@AlfredIsac 3 года назад

@@citizenscientistsworkshop1948 pycnometer. I used your method. It is working well with disttiled liquids such as vodka. But for wine, I get more than 1 density and hence when I look the ethanol table the comparisons start will alcohol value less than one.

@citizenscientistsworkshop1948 3 года назад

@@AlfredIsac the pycnometer always gives you the correct answer if you are using it correctly. If you are getting an answer that you did not expect, and you are sure you are making the measurement correctly, then you need to alter your expectations to be consistent with the value. I don’t know why your wine has the you are measuring, but it’s not a problem with the technique. It must be a property of your wine.

@axelmani9958 4 года назад

how to determine absolute density of the soil ?

@jacobcarlos8699 4 года назад

I don't think you typically use a pycnometer for soil samples but I suppose you could do the same thing shown with the BBs in this video. Just make sure you oven-dry your soil sample first (to remove any moisture content), then fully saturate the soil in the Pycometer to weigh it. You could also lookup ASTM D7263 if you have to access to it, its the Standard Test Methods for Laboratory Determination of Density (Unit Weight) of Soil Specimens.

@materialgirl4896 3 года назад

There is a specific type of pynometer for soil

@rangergrade 2 года назад

Why use this instead of a graduated cylinder? It seems to do basically the same thing:mesure volume

@firesurfer Год назад

I guess for simplicity's sake. It's a fixed volume making measurements easier.

@methoverlord3976 4 года назад

density of distilled water is 1 g/ml at 4 degrees celcius not 0

@muetaz_zaydan 2 года назад

I think a syringe is cheaper specially after finding out these pycnometers can be off by 5 ml

@MarYouSeeE 5 лет назад

first you suggest that everybody should buy one of this little containers cause their accurate then turns out they are not accurate after all and should calibrate them wouldnt be easy to find a proper container in the first place.

@citizenscientistsworkshop1948 5 лет назад

Actually, it is TRIVIAL to calibrate the a pycnometer, as I show. Just measure the mass of distilled water that fills the container completely, then divide that mass by the density of distilled water, and you're done. Once the device is properly calibrated you will have a very simple and way to measure densities with great accuracy and precision.

@jrichardjacobs34 3 года назад

Good video, Shawn. But ... ahem ... an edit problem. The word 'density' on the cube is spelled d-e-n-i-s-t-y. I know, picky picky.

@citizenscientistsworkshop1948 3 года назад

Details, details. Oh well, that one slipped by me.

@jrichardjacobs34 3 года назад

@@citizenscientistsworkshop1948 -- I know. Rotten devil in the details. Easy fix, or no?

@citizenscientistsworkshop1948 3 года назад

J Richard Jacobs : It would be easy to fix the original video if I still had it on my computer. But if I then re-uploaded it all external links to it would be broken. That would cause more harm than good. I’ll investigate the editing tools that exist on RU-vid, but I do not think this is easy to fix with the tools there.

@aSlimyDragon Год назад

Great video, but the massive discrepancy of the pycnometer is bugging me. I feel like you should've poured the full volume of water into a graduated cylinder just to confirm there wasn't something off with the calculations somehow. Because that seems really weird for the printed value to be so wrong. Also, you seem to be using "trivial" to mean "easy". The only non-mathematical definition of trivial has it referring to something that's of little worth or value. Like trivia facts, which are just small, relatively unimportant tidbits about a topic. Might be fun to know, but ultimately not very important.

@citizenscientistsworkshop1948 Год назад

You’re absolutely right. I should have demonstrated the volume error directly. But the electronic scale was calibrated, and the self consistency with the measurements make it clear what the true volume was. Also, thanks for the correction re “trivial.” I have always thought trivial to mean both “trifling” and “ easy to perform.” I’ll keep your point in mind in the future.

@yourmomhatesaxel 3 года назад

goat

@citizenscientistsworkshop1948 3 года назад

I hope the word you were looking for was “good”.

@yourmomhatesaxel 3 года назад

goat means greatest of all time 😅

@sodoododnyma8864 9 месяцев назад

I have physics lab tomorrow, prayForMeGuyzz

@tajcnsun8427 2 года назад

Gak gak gak gak ngerti aku gak ngerti dengan ini semua

@mohdmirza365 5 лет назад

Wrong process, fill it to the given mark.

@citizenscientistsworkshop1948 5 лет назад

Mohd Mirza I think you need to watch the video more carefully. There is no mark on the device. This isn’t a volumetric flask. It’s a pycnometer. If you have an objection, please state it clearly enough for me to understand your concerns and to address them properly.