The Mole: Avogadro's Number and Stoichiometry

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Yes, I know moles are adorable furry creatures. This is a different kind of mole! A numerical mole. And we need to understand them to be able to make predictions about reactions. Let Professor Dave take you through the finer points.
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Опубликовано:

5 июл 2015

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Комментарии : 475

@indrareddyakkaluri3733 6 лет назад

Your intro is legendary

@IITJEEADVANCEXD 2 года назад

And outro also

@sirishavejendla4156 2 года назад

Telugu Vaaru kada meeru

@matthewcecil8552 7 лет назад

I'm a senior biomedical science student from FSCJ, and previously a tutor. You did a great job in this video. Definitely a clear and concise explanation, which is the most important aspect of any chemistry lesson with maths.

@ProfessorDaveExplains 7 лет назад

thanks kindly!

@missishu2431 7 лет назад

Sir you really maid my day...i finally got interested in Chemistry

@tonybatycki Год назад

Wow never expected to see FSCJ in a comment. Anyway, Go Jags!

@josiahwhite3157 5 месяцев назад

@@missishu2431Ain’t no way u said “maid” learn grammar wit yo goofy ahh

@MoleLife-mn9bq Месяц назад

I am the real Mole

@zucchini9177 6 лет назад

OH MY GOSH I AM ABOUT TO CRY! I have a test on this tomorrow and know nothing about the material but now that I've watched this I finally do. Thank you so much!!!!!

@jamesmanning8269 4 года назад

Diana Enriquez how’d the test go?

@grantlong7788 4 года назад

did you pass

@RandomPerson-hd9sb 3 года назад

@@grantlong7788 sure, passed away

@valestuffs 3 года назад

no she ded

@zucchini9177 3 года назад

ValeStuffs I’ve been summoned from the dead?

@Fjuron 2 года назад

To fully understand, I often have to watch your videos twice or pause because the information is so densely packed. But I love it. Feels very good when you figure it out. It forces you to think about it in your own way and build your own mnemonic. Active learning. 👍

@lordwetrustl7080 6 лет назад

I knew Jesus was a teacher but i didn't know he taught chemistry

@hehehehaw7 5 лет назад

Underrated comment, take my upvote.

@fallencity4066 4 года назад

Sophisticated comment about underrated comment , Here take my up-vote.

@elmerlopez4146 4 года назад

Piggintins my chem teach calls him science Jesus

@grantlong7788 4 года назад

he is NOT jesu:(

@marktaylor7162 4 года назад

I thought Jesus was a car mechanic, because Jesus built my hotrod.

@mitchyboy41 3 года назад

Just wanted to say, to all the students, trying to comprehend this, you're not alone. I've pulled out my hair for 3 days trying to learn this. Just breathe, getting frustrated won't allow you to learn it any easier.

@AAIVE 3 года назад

thanks, mitch!

@misfire32 3 года назад

@@simoncharlene8947 Thx

@megajihamsikaa 3 года назад

Thank you

@real_GANGSTA_ 2 года назад

Which standard you are in

@SCP--mw7tx 2 года назад

i struggled for a few days, and then soon realized it's just some easy mathematics.

@charlieann8661 7 лет назад

Thank you for taking the time to do these videos!

@freedomofspeech122 8 лет назад

Thank you for all of your videos! You're a great teacher. Thanks for all of your hard work and efforts to help us chem students!

@ProfessorDaveExplains 8 лет назад

+May C it's my great pleasure! spread the word!

@freedomofspeech122 8 лет назад

+Professor Dave Explains I sure did! I shared your channel with a few homeschooling Facebook groups in BC, Canada.

@tonybatycki Год назад

@@ProfessorDaveExplains any recommendations of books about Avogadro and the process of how he developed his equation? Fascinating that he found this number.

@christinayang2658 2 года назад

okay you know what I got an A in chemistry in highschool but never knew the purposes of these concepts..... I really enjoy your constant reasoning on why we use moles in the first place! It really puts the whole picture into perspective vs just having my teacher mostly explain the math portion so I just learned how to do the math to get correct answers on my exam and homework..... the big picture and purpose for me was for sure lost. Thank you for your reasonable explanations!

@xdanx01 7 лет назад

I finally get stoichiometry! Thank you so much for this video

@doremi1414 2 года назад

I'm a Korean student and I'm really into science. Your videos helps me a lot cause you use simple words, giving great explains. You are the best prof for me. Thanks a lot for your hard work.

@kentheengineer592 Год назад

Learn More About Analytical Math & How to Think in Abstraction

@doremi1414 Год назад

@@kentheengineer592 Maybe in university. thanks for the recommendation

@williamconrad1087 4 месяца назад

By simple, you mean words like stoichiometry and stoichiometric.

@TenNineD Месяц назад

@@williamconrad1087it’s like Dave saying “for example” rather than saying “For a concrete demonstration of the illustration, we can observe”

@titidechdamrongwut1351 7 лет назад

Keep pushing this VDO , I will go thru all your VDO. Thank you 3 times.

@---fb6zs 6 лет назад

Very easily to understand! Thank you so much 😊 I will watching all of your videos ❤️

@sarayhazuki4709 4 года назад

Thank you so much for your videos! your videos are short and have all the information, plus your illustrations help a lot to understand more!

@expiredflunky5603 6 лет назад

Thank you jesus

@sreevivasaraghavan6848 3 года назад

I am thing professor Jesus

@edwintafalla589 3 года назад

Thank you Professor Dave. So much learning about your upload videos

@kent7966 5 лет назад

I have been using his videos to study for midterms

@roysolomon4755 5 лет назад

Your the best

@OIOTV-zo9qp 7 лет назад

Thank you for helping. hard to find people like you. I am going to share it. Thanks

@austinsporn8432 7 лет назад

you have saved me

@wilts8965 4 года назад

I see what you did there

@HenriFaust 2 года назад

In the first example, you rounded once for each conversion factor. In the second example, you combined all the conversion factors into a single operation and only rounded at the end. These are not the same method, and achieve differing results. *Method 1:* 32.8 g H2O and 73.0 g O2 *Method 2:* 32.7 g H2O and 72.7 g O2 Which method of rounding is correct?

@stu_0618 3 года назад

You litterally saved my chemistry GCSE. Thank you so much!

@veryhealthy9962 Год назад

If you are a self-learner, believe me when I say the amount of info Dave puts per video is extremely dense, but listen patiently and let it run through your brain until you get it. That tingle in the brain is similar when you finally understand something in arithmetics!

@ajibolakehindeaishat5892 Год назад

Thanks for all your chemistry videos

@saitejamandiga2916 6 лет назад

Thanks for all of ur videos sir My sir taught us but I didn't understand but after seeing ur videos anyone won't have ang doubts

@praviinashanbalagan1563 7 лет назад

You have everything I need thanks how about making video clips of you doing experiment in General chemistry maybe it helps me to know the procedure

@gbmsg282 3 года назад

First time I was able to actually understand the reason behind all those calculations. Thanks man!

@k_Why 2 года назад

Just had a quick question. I did the comprehension exercise in kind of a roundabout way calculating the weight of the CO2 and H2O then using both those values to figure out the weight of the O2 and adding them. I got the right result, but the weight on both sides of the equation isnt actually the same. I got 92,7g on the left side and 95,4g on the right side. I doubt that we actually created mass anywhere especially because this looks like a combustion reaction that releases energy. Mass defect wouldnt be enough to explain almost 3 grams anyway. Now did i just miscalculate and got the right solution through dumb luck or what's going on? Edit: figured it out. i mistakenly used 46 as the as the atomic mass for CO2 when its actually 44. i still got the right solution because i devided by that same number when i converted to O2

@user-ww3pf4cr8c 3 года назад

Your explains is more than great Mr Dave👏👍

@jackmorvan813 4 года назад

Great video, David!

@angeliemaebonaobra4448 7 лет назад

Professor Dave! Thank you!

@akira_asahi 2 года назад

Thank you for the video. I am grateful for your time and contribution. Kind regards, Akira.

@jacquelineoonzhien3234 3 года назад

Thank you so much for the video!

@mychaelpierce8049 2 года назад

Great video. Thanks for sharing!

@alexandrashields2600 3 года назад

Dude, thank you so much for helping explain this!! Bravo!!

@stupidsapien7304 2 года назад

Thank you professor ! It helped me alot.

@connerbrandy9185 3 года назад

Thank you, Helped a lot!!

@GriteKidsTV 3 года назад

i wasnt listening in class last time and i have a test, you just saved my ass

@chiklachikla7641 2 года назад

So how did the test go

@ThingsOut 8 месяцев назад

I don’t understand this! 3:27 How do you multiply?

@sunflowervol.6790 5 лет назад

Thank you so much sir. It's probably the best way to explain it so simply😊...A small request sir, Can we have an extended video on the same topic as it is a whole big chapter piled up.... plz do it if possible sir.

@ProfessorDaveExplains 5 лет назад

what's not in this one that you're looking for? it might be in another clip.

@cardiyansane1414 2 года назад

@ 5:24 It looks like they have done two conversions at the same time , maybe it would be easier to understand it is broken down step by step

@MARTZX1111 3 года назад

Thank u for this tutorial.. its very helpful..

@zeinabmuhammed4549 6 лет назад

Thank you professor dave 😇

@maesie_alexa4084 3 года назад

Watching 2 hours before deadline!! Thank youuu

@dominicnikon6276 5 лет назад

Awesome video thank you so much

@jzzh1 6 лет назад

thanks so much! you got a new subscriber

@user-mu5fw3ik2w 4 года назад

2:50 Why is this composition reaction not displacement reaction?

@jimbynumsierravistahs2319 4 месяца назад

I want to use this in a high school chemistry class. My issue is the ambiguity when it comes to where the numbers came from when going from mole of 1 thing to moles of the other. Somehow emphasizing that the numbers came from the balanced equation would prevent a lot of confusion.

@ameennasser5674 8 лет назад

if you please explain some mathematics that is mostly in chemistry so that we understand faster the fraction part is confusing if you could explain it in easy way that would be wonderful

@ProfessorDaveExplains 7 лет назад

it's just basic arithmetic, but don't worry, i've got math tutorials coming soon!

@triple_gem_shining 9 месяцев назад

literally love dave

@jimjimmy3131 6 месяцев назад

I got only one question, why did that chemistry teacher that hated her job and students in general made my day so difficult instead of simply explaining to a 15 year old kid such a formula. Hod damn, why do teachers become teachers when they cannot teach and dislike kids ffs.😅 even after all those years of this video being uploaded. I would like to thank you for the explanation.

@socceralex12345 7 лет назад

Thx 4 the vid

@old-tech Год назад

Remember that, like he said, the answer may very depending on where you round. In the case of the comprehension question, the answer is based on if you didn't round until the last number, which totaled to 72.7. If you did what he did in the first example question, and round the answer of 20 • (1/44) to 0.455, you'd end up with 72.8g for the final answer. If you ended up with that, you technically didn't do it wrong. Again, as Professor Dave said, it depends on when you round.

@DaveGrean Год назад

Thanks for reminding me, I got 72,8 despite having used a calculator so I was losing my mind, lmao

@callumalmighty 2 года назад

Nice one Dave!

@study4life443 Год назад

Hello, I've been confused at 4:03 Where did 1moleC3H8/44.0 g C3H8 come from? I know that we need to multiply by one in order to not change the equation, the thing that's confused me is how do we know that C3H8 has a mass of 44.0 g.

@ProfessorDaveExplains Год назад

It's the molar mass, just use the periodic table.

@spitfire184 5 месяцев назад

For anyone reading this after the fact, I think it's: Carbon (6 protons + 6 neutrons) x 3 = 36 Hydrogen (1 proton + 0 neutrons) x 8 = 8 36 + 8 = 44

@inoxide5454 9 месяцев назад

i love being taught by a Foo Fighter

@richardtriance5207 9 месяцев назад

"i've got another confession to make..,"

@RedToastt Год назад

where do we get the 20g from at 3:28?

@madylinn9235 5 лет назад

Thanks prof

@priovag2632 3 месяца назад

Your teaching is great

@steezyspamsl223 5 лет назад

saving me from chemistry finals 😂😭

@zaynahadi2699 2 года назад

i have a question from where did you get 32 in the last comprehension ?

@carultch 2 года назад

That's the molar mass of 2-atom oxygen, which is oxygen's elemental form where it is covalently bonded to itself. Unless otherwise specified, oxygen refers to 2-atom oxygen, rather than single atom oxygen (that will seldom exist). Ozone would refer to oxygen's 3-atom form. The same is also the case for any other element that more commonly exists as a 2-atom molecule than a stand-alone atom, such as nitrogen, hydrogen, and any halogen.

@EpicSchizophrenium 4 года назад

So If I would know how many Mols of O2 I have than would I have 4/5 of a mole of Water because the ratio is 4/5

@Roy-mk9zl 5 лет назад

Thanks sir.

@linaberkani309 4 года назад

Thank you sooooo muuuuch

@yigitcanbaysal824 2 года назад

I wonder professor David what is stoichiometric point.Could you explain me?

@jiinjung1445 4 года назад

Hi, professor Dave. May I ask you what's sig fig of the last question? I rounded up 20/44 as 0.454 as I thought the sig fig was 3? but it gave me a wrong answer.

@DaveGrean Год назад

The sig fig are 3, but you rounded wrong. According to my calculator the result is 0,454545... so rounded up it makes 0,455, not 0,454. Remember you need to round up from 5 onwards, not 6!

@ciaranlonergan9910 3 года назад

Love you Dave

@andrixleenocaspe3573 Год назад

So you don't account the CO2 when doing stoichiometry?

@briannamoran7555 5 лет назад

I don’t understand where the 32.0 grams came from can you explain?

@carultch 2 года назад

Oxygen has an atomic mass of about 16 amu. Oxygen's most common elemental form is the O2 molecule. The molecular mass of an O2 molecule is 32 amu. When we consider a mole of oxygen molecules, this means our amu units get promoted directly to grams, because there are by definition 1 mole of amu in 1 gram.

@just7815 2 года назад

prof dave is a genius. he makes a lesson no brainer.

@Dragon-Slay3r 9 месяцев назад

That was the najd interview yesterday

@sskybluezen 4 года назад

I suck at chemistry, but after watching couple of your vids I might pass in my upcoming exam. Thanks a lot !!!!!

@NeuronalAxon 4 года назад

How'd it go?

@peterclancy3653 9 месяцев назад

All I can remember of stoichiometry is warm summer days, blowflies buzzing on the windows and the drone of a old chem teacher. 56 years ago. AD(after Dave ) it finally clicked!

@Stephenc35753 22 дня назад

So you said that 0.455 moles of propane is equal to 1.82 moles of water, but wouldn't you have to add in the moles of the O2 as well? Seeing as you can't make water H20 from just the propane?

@ansumann 2 года назад

Thank you so much

@user-xu6ie9js9z 2 месяца назад

Bro is about to measure the amount of alcohol molecules that he's going to turn his glass of water into.

@ammyvl1 2 года назад

it took me a couple tries but I got it! thanks so much

@adhiyanthaprabhujeyashanka2091 3 года назад

Yes I finally understood this😉, thank you so much professional professor dave, love from India 😁, I will suggest to my friends to watch you, the best as always ❤️

@Dragon-Slay3r 9 месяцев назад

With a botox jab?😂

@johnnyWZL Год назад

Can we use O2 to find how many moles of water there is?

@loshithasahan7164 6 лет назад

Before I watch this video this lesson made a MASSIVE headache for me.......THANK YOU VERY MUCH PROFESSOR DAVE !

@gabriels2395 6 лет назад

Thank you so much again! So I can say that "mole" is the number of protons (or neutrons) needed to get 1 gram of them. Right?

@ProfessorDaveExplains 6 лет назад

yes that's one way to look at it! technically it's the number of carbon-12 nuclei that will equal 12 grams, but the math works out almost exactly the same.

@alderamin1402 2 года назад

I didn't understand what you are saying can you explain it to me

@demon_hawkeye5269 2 года назад

@@alderamin1402 I think it's due to the fact that protons and neutrons are almost the same mass so they both count as 1amu, so since moles are amu converted into grams 1mole of protons/neutrons would be 1g

@alderamin1402 2 года назад

@@demon_hawkeye5269 yes probably since he /she said just the number of protons I did not get it. thanks but I also really wonder about why 1 amu is equal 1 g. I asked it to my chemistry teacher but she did not know :'''')

@demon_hawkeye5269 2 года назад

@@alderamin1402 it's not that it's equal to 1amu, in fact it's very much the opposite to convert a 1amu neutron to 1g of neutrons you would have to have an avagadro's constant amount of that 1amu neutron, essentially, this is the number of things (be they individual subatomic particles, individual atoms, molecules or whatever else) in one mole of that thing it is 6.02×10^23 this is the same for anything you're trying to get a mole of

@thej680 7 лет назад

it took me a while to figure out that you just made up the 20g C3H8 and basically said that C3H8 is 1/4 the moles of water in the product, so you could multiply the 20g of C3H8 to figure out the moles of water. Then you could convert that into grams afterwards. However, is it possible to convert, say we knew the mass in grams of 5O2, into moles of water with the same reasoning that the ratio of moles of oxygen to moles water is 5/4?

@ProfessorDaveExplains 7 лет назад

yes absolutely! just make sure you convert mass of O2 into moles of O2 first!

@kaylapoulsen2603 7 лет назад

How did you get that 4 moles of H20 is equal to 1 mole of C3H8? You said they were in a 4:1 ratio, but I'm not sure how you got that ration. Thanks :)

@kaylapoulsen2603 7 лет назад

I see that you are using the coefficients, but I don't get why coefficients put them in a ratio

@ProfessorDaveExplains 7 лет назад

if one propane molecule produces four water molecules, then one mole of propane molecules will produce four moles of water molecules! it's the stoichiometric ratio of the reaction, which comes from the balanced equation.

@Dg-ii5xk 2 года назад

Thanks a lot!

@ameennasser5674 8 лет назад

i didn't like chemistry till saw your chanel thank you boss

@lakshminarasimhamurthyvish9204 8 лет назад

That's how #ProfessorDaveExplains !

@grantlong7788 4 года назад

you welcome mr. bossman. glad you sawed chanel

@ndappypaulus3064 Год назад

Professor i still need help in moles

@Dragon-Slay3r 9 месяцев назад

Ive already been stung there 😂

@universal6906 3 года назад

Thanks for You clear my dought

@nelson138 Год назад

In the comprehension section I get 72 gm , it says 72.7 grams . I'm multiplying 2.25 moles of O2 by 32.0 grams O2 and that gives me 72 grams of O2,Am I wrong?

@irenecuartocruz6371 4 года назад

Thank you because we have a reporting about this... Thank you very much... It is a big help...

@arway4766 3 года назад

I don't know how good you are at making music but could you possibly make a full "professor dave explains" song... Idk what lyrics you'd put into it but you're the expert add some science topics make them rhyme do whatever it honestly doesn't matter as long as I get a longer version of the intro lol

@ydelmaeselda402 3 года назад

i was wondering where did you get the 20.0g in the 4:22?

@ProfessorDaveExplains 3 года назад

given information

@ydelmaeselda402 3 года назад

@@ProfessorDaveExplains thank you! your videos help me in my chemistry class

@mxoeneod90 3 года назад

@@ydelmaeselda402 same problem for me but I just watched one more time with captions

@narniansworld9735 3 года назад

Thank you sir ❤️🙏🙏

@atanaciogarza7176 3 года назад

Thank you

@Skrilleze 2 года назад

is 0.5 mole of chromium (III) oxide (Cr2O3) the same as 0.5 mole of Cr+ ions and 0.5 mole of O- ions? or how does it work?

@ProfessorDaveExplains 2 года назад

well there are two chromium ions per formula unit, so double it!

@sunflowervol.6790 5 лет назад

Hello sir. Thank u for the quick reply. Stiochiometry has this sub topics which were not included - eudiometry, limiting reagents, volumetry and Iodometry which we would like to be explained by you sir as you r the only one to keep so simple and to exact point. Hope you will help. Thank you sir.😊

@ProfessorDaveExplains 5 лет назад

limiting reagents has its own clip so definitely check that one out. the other words i've never even heard of!

@sunflowervol.6790 5 лет назад

Ok sir.