GCSE Chemistry - What is a Limiting Reactant? Limiting/Excess Reactants Explained #27

[@Cognitoedu]

If you’d like to practise the material covered in this video, check out our platform at www.cognitoedu.org - it's totally free, and has been built to make learning and revision as easy as possible. The main features are: - Lessons organised by topic, only the lessons relevant to your specific exam board and tier are shown. - Automatic progress tracking. Progress bars tell you what you’re doing well at, and what you need to spend some time on. - Practise quizzes so you can test your knowledge. You can quiz yourself on any combination of topics you like. - A huge number of fully-hinted questions that take you step-by-step through some of the trickiest calculations & concepts. - A comprehensive bank of past exam papers, organised both by year, and also by topic. Amadeus & Tom

[@LevelUP84]

I’m a little confused, in the 2Na(small 2)O equation, how comes you only add 2 x 23 and not 2 x 46 as you balanced out the equation by adding the 2 in front so I thought it would be 2 x the 2 and not the 1 if that makes sense? 🤪 I’m new to this. Thanks.

[@salmaahmed8726]

This channel is single-handedly helping me get through Sciences and Maths especially in uncertain Covid times. Thank you so so much for all your hard work!

[@Cognitoedu]

Thanks Salma, so great to hear that

[@mohamedking6297]

Are you somali salma

[@NicolasYan-jy4vb]

I kid you not I absorbed more information about limiting reactants in this 4 minute masterpiece of a video than I did in an entire year of chemistry lessons. Cheers.

[@mayakleinberg6013]

thank you so much this has really helped me to understand this for my mocks. I struggle very much with chemistry and really appreciate good gcse videos

[@Cognitoedu]

Hi Maya thank you so much for taking the time to leave us a comment and let us know the videos are useful to you (it really helps the channel to grow/get seen) - we really appreciate it! Good luck with all your work!!

[@xfreja]

i struggle with chemistry too :( but i’m so stressed that i don’t understand half of the stuff

[@StrayNightsMike]

i genuinely still cant belive how u can make me understand stuff in 5 mins which would take hours for me to understand in school

[@ibphysicsclassroom]

Cos you genuinely don’t pay attention in class but here you take responsibility of your own learning. Those who did in class understood it

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[@stu_0618]

This man is single handedly saving my chemistry GCSE. Could not be more thankful!

[@Cognitoedu]

🤩🤩

[@savagex_2008]

I can’t believe it, I’m watching this video one last time before my exam tomorrow. And then I’m never gonna study chemistry in my life again.😢

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this the best channel for gcse videos have seen so far. really appreciate your efforts these have really helped me with a lot of concepts for all sublets for that matter. hats off to the team!!

[@nikki2423]

Idk why this video doesn't have more views, it was so useful! Thank you, just subscribed :)

[@mubeenkouser7695]

Even I don't understand seriously and I am so glad that I have found this on perfect time awesome video I literally wrote each and every thing you said in the video

[@beccalloydpoetry]

Thank you so much for all your videos. They help me in all the sciences so much! My mocks are this week and this has helped me to succeed so much!

[@saadiaa260]

This is a clear and coherent explanation. It is phenomenal! Really helped me to understand this topic a lot better:)

[@sumaiyaansari9968]

KZbin teaches me more in 5 minutes than my teacher in a few months. Thank you so much ✨

[@Asa_Stanley]

I just want to say thank. I am taking my final assessment for science today and I want to say thank you for helping me through the stressful process of exams.

[@Cognitoedu]

Hope your assessment goes well James 🤞

[@brooklyntafirenyika9103]

Helping me when ny science teacher won't, this is a life saver ❤

[@anthonyfaddul3582]

Thank you so much, very good explanation, I finally understand

[@Cognitoedu]

That’s great to hear! Thanks 🙌

[@poppymaeeee]

thank you Jesus for these videos saved my life

[@Cognitoedu]

He says you’re welcome 🤙

[@abishasivakumar9001]

hi, when you find the mr of na2 surely you do Na * 2 but whenin the video u did 2Na2 surely you have to times it by 4 a bit confused.

[@lukebrice2040]

Although it is of no relevance to you now, you do not need to multiply the Mr by the coefficient(2) at the front of the element.

[@subbhy3791]

You could do that and then you don’t need to do the molar ratio of 2:1. It will give you the same answer regardless.

[@LevelUP84]

We are confused about the same thing, thank goodness it’s not just me. 😅

[@Study_account1603]

Hi, regarding limiting reactants, will that change how we calculate the mass? Because at 4:02, you calculated the mass, as if there was no limiting reactant (does this limiting reactant really matter, and if so, when would it effect the equation) Thank you very much!!!

[@IamtheSmoosh]

thank you so much for this! I had missed a lesson and had no idea what was going and this helped me greatly!

[@AryanGhosh-y7o]

Thank you so much this video was so helpful! The limiting reagent is the one topic that kept me stuck with stoichemistry but this allievated the burden!

[@zen8877]

Thank you! This helped me to really understand the topic more!

[@xpertgamervloging7197]

Thank you so much this video clears my concept about limiting reactant ❤

[@ktsbfilms4639]

I have a question, at 3:59 when you add the sodium mass and oxygen mass to get the mr why dont you do 4 sodium since there’s a 2 in front of the Na2

[@DailyDoseOfFacts456]

Because that was just to balance the equation the actual compound is na2cl

[@homeexercise1122]

Thanks for explaining this in easy way i finally understand 🥰

[@nawal8790]

at 3:12 , why is the ratio for sodium 2:1 when sodium on both sides are 4? shouldn't it be 1:1 ?

[@nawal8790]

@@starlesscitiess thank you so much this helped a lot :)

[@soyadrink9831]

I'm just falling this. I just dont understand

[@TasneemPrangon]

Same

[@ShahdAl-Ali]

You are also failing English class. It’s failing not falling

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[@eshal3210]

Fr

[@tealisbored]

😭😭🥄​@@ShahdAl-Ali

[@aksimator2]

Thanks a ton! I needed it!!

[@BrusiedLavenders]

This video is so useful. It helped me very much to get through limiting reactants

[@Cognitoedu]

Ah thanks Khansa, so glad it helped! 👍

[@awsafrkhan4356]

Hello Mr Cognito! At 3:22 you multiplied 5 by 2 is the 2 Na or 2Na20 < the original one.

[@nerdyboi2000]

is this channel for key stage 3 (KS3)

[@irneaa]

Thank you

[@ibrahimbjoe001]

Good and brilliant 🇸🇱🇸🇱🇸🇱🎤🎤🧠📚📖📚

[@faithpraise9883]

Thank you so much. Are all your videos for students doing higher tier?

[@magicmissile9323]

now that my schools science departments terrible, i genuinely feel like telling them to use cognito over teachers and save the money

[@User-ki1ws]

at 3:02 shouldn't you have multiplied 23 by 4?

[@khaif.3376]

i was thinking the same thing oof

[@LevelUP84]

😭 me to. Now I have to turn to my thick accent science teacher who makes it complicated.

[@LevelUP84]

I thought it would be 4 x 23 because he put the big 2 in front of the equation. And 2 oxygens instead of 1.

[@skyblockplayer1916]

thanks maaaan

[@houseflyer4014]

only helpful video i found on the topic

[@Cognitoedu]

Thanks Hasan - really appreciate the comment!! Great to hear it was useful, and comments help the videos get seen which is great for us 🥳

[@keeranaravinthan]

at 2:52 why does he find the Mr of Na and not 4Na, arent they completely different?

[@murkeowri658]

very helpful thank you so much! Please make a video or put a link on how to solve for stoichiomery

[@BobMarley-yz4wh]

Thx! Great vid.

[@Cognitoedu]

Hi Abdul, thanks for the comment! We’ve double checked and we’ve done it for 115g which is exactly 5 moles of sodium. So it would produce 2.5 moles of sodium oxide which would have a mass of 155g. Have we understood you correctly, or is there something else you think we’re missing?

[@BobMarley-yz4wh]

Cognito yep sorry. Misunderstood. It is correct

[@Cognitoedu]

@@BobMarley-yz4wh No worries at all - we definitely want to know if something's wrong so we can fix it!

[@khaledbahy560]

Thank you 👍

[@williamhicklin6141]

Thanks for helping 🤌🏻

[@EldanaBirhane]

thank you very much you saved me😇😇

[@ayanahmed4010]

I love this Cognito❤

[@jenadaraji7408]

This was sooooo useful!

[@F1nn1810]

thank you for the very useful video

[@mayaa_yt4382]

2:56 help how did you get 115?

[@bonakim9202]

The question already gives you the mass: “when 115g of sodium is burned in the air”

[@roseyholcombe6714]

does anyone know how he got 5 for moles in the question. i cant figure it out

[@LevelUP84]

Confused me to, I thought it would be 4 moles.

[@zilovesmaths]

@@LevelUP84 He used the formula Moles = Mass / Mr The mass of the sodium is given in the question ('when 115g of sodium is burned in air') So we know 115g is the mass On the periodic table, the relative atomic mass of sodium is 23 So now using the formula moles = mass / mr moles = 115 / 23 = 5 So 5 moles Hope this helps!

[@kashishkazmi123]

At 2:31 why its not 2Na at the reacrant side and just Na²O as product?

[@LevelUP84]

How did you make that tiny 2 and O?

[@pxstelrxses1361]

​@LevelUP84 hold the 2 on your keyboard and it may come up

[@alexanderivankovic8966]

2na2O means there are 2x(2Na and O) which is 4Na and 2 times O. Since non metals form molecules with themselves and metals no then it will be 4Na plus O2

[@Ryan-tt4ph]

For the last example, why don’t you multiply the mr of the product by 2 Cuz there is a big 2 on the left of it? I thought that just means multiply the whole product by 2

[@Aahir.]

I dont know either could you help??

[@LevelUP84]

I’m confused about the same thing.

[@RoseInnn]

Thanks a lot!

[@Cognitoedu]

You’re welcome!

[@prettylife6086]

how.. how did yk its Na2O when Na nd O2 react? like howd yk we'd need 2 sodiums? is there a video for this im lost D;

[@galefray]

Alkali metals reacting with O2 can either give either Metal Oxide, Metal Peroxide or Metal Superoxide. You should remember that from video #11. Recap: Sodium Oxide = Na2O Sodium Peroxide = Na2O2 (A good way to remember perodixde is that it semantically tells you what it is, sodium PER oxide so... yeah lol. Overall things to rememeber from Video #11: All Alkali metals can react with Oxygen, Water or Chlorine. When reacting with Water: Metal Hydroxide + Hydrogen [Li + H2 ----> LiOH + H2] ~~ When reacting with Oxygen: Lithium + Oxygen ----> Lithium Oxide Li + O2 ----> Li2O ~ Sodium + Oxygen ----> Sodium Oxide Na + O2 ----> Na2O Sodium + Oxygen ----> Sodium Peroxide Na + O2 ----> Na2O2 ~ Potassium + Oxygen ----> Potassium Peroxide K + O2 ----> K2O2 Potassium + Oxygen ----> Potassium Superoxide K + O2 ----> KO2 ~~ When Reacting with Chlorine: Metal + Chlorine ----> Metal Chloride (Remember, Chlorine is a halogen all halogens become a halide when they react).

[@suryannair4804]

this is god sent even tho my exams are cancelled

[@EcoHotdog]

Suryan Nair no

[@swethavarshi3802]

What if no information about mass is given and we have to find the number of mole for calculating the limiting regent? How do we do that?

[@HassaanSajeer]

is the cation always the limiting reactant?

[@jenadaraji7408]

Now I finally get this topic by reading the description lol

[@uwotm8770]

bless you

[@LevelUP84]

I’m a little confused, in the 2Na(small 2)O equation, how comes you only add 2 x 23 and not 2 x 46 as you balanced out the equation by adding the 2 in front so I thought it would be 2 x the 2 and not the 1 if that makes sense? 🤪 I’m new to this. Thanks.

[@crxnge4483]

yeah i think its because the rfm is only the sum of the atomic masses of the atoms and that is not including the number of molecules

[@tezawr3963]

Thanks

[@tanvidge]

Thanks bc im a reporter of this topic in my ps class

[@graceabigail331]

Hi, do you know why it is important to have excess of one of the reactants?

[@abishasivakumar9001]

it's not important to have an excess of one of the reactants, It is important that you know that one of the reactants is a limiting reactant and that means the other reactants are in excess, hope that makes sense :)

[@graceabigail331]

@@abishasivakumar9001 ahhh right okay, that does make sense. Thankyou!!

[@sindhhh]

saving me 2 weeks prior mcat is insane

[@BibiAmna-m3s]

Why limiting is not applicable to reversible reaction

[@sueweng7307]

He iş the goat

[@arusu6478]

Exams in less than 3 week. Hope you ready

[@erikakisakka]

I have a chemistry paper 1 mock tomorrow and I am watching binge watching all the relevant videos ! They are SO helpful ! Thank you, you have saved me :)

[@Cognitoedu]

Thanks Erika, glad we could help 👍

[@mohamedking6297]

By any chance were you an IB student

[@WEEBWHOSELLSWEED]

Why Na+O2 can't give NaO rather than Na2O

[@JustinaMulengaChisamamba]

Sir how did u find 2.5 of NaO

[@rrrawat2333]

2 to 1 ratio

[@queensharabillones6297]

How do you get the 4Na+O2

[@zilovesmaths]

You need to balance the equation, as there need to be an equal amount of reactants and products on each side He's linked his video of balancing equations in the description so watch that!

[@tillysalmon585]

Mocks tomorrow ay ay ay

[@galefray]

For everyone wondering where the NA2O came from: Alkali metals reacting with O2 can either give either Metal Oxide, Metal Peroxide or Metal Superoxide. You should remember that from video #11. Recap: Sodium Oxide = Na2O Sodium Peroxide = Na2O2 (A good way to remember perodixde is that it semantically tells you what it is, sodium PER oxide so... yeah lol. Overall things to rememeber from Video #11: All Alkali metals can react with Oxygen, Water or Chlorine. When reacting with Water: Metal Hydroxide + Hydrogen [Li + H2 ----> LiOH + H2] ~~ When reacting with Oxygen: Lithium + Oxygen ----> Lithium Oxide Li + O2 ----> Li2O ~ Sodium + Oxygen ----> Sodium Oxide Na + O2 ----> Na2O Sodium + Oxygen ----> Sodium Peroxide Na + O2 ----> Na2O2 ~ Potassium + Oxygen ----> Potassium Peroxide K + O2 ----> K2O2 Potassium + Oxygen ----> Potassium Superoxide K + O2 ----> KO2 ~~ When Reacting with Chlorine: Metal + Chlorine ----> Metal Chloride (Remember, Chlorine is a halogen all halogens become a halide when they react).

[@myboyfriendsbetterthanyou4082]

you are a legend, i was so lost and forgot the basics of chemistry

[@Glowdits]

who the fuc are you thinking u r u btch asssholeee

[@Urmomlol6969]

Dumb question but why is na+o2 not nao2?

[@zilovesmaths]

@@Urmomlol6969 Probably not gonna be of any relevance to you now but The Na + O2 are reactants, they're just separate elements However, when they react then they become Na2O (on the right side of the arrow) So at the start it's Na + O2 because they are separate at that time, but then after they react then they become Na2O Hope this helps if you still need it! 😂

[@LevelUP84]

I thought it would be 4 x 23 because he put the big 2 in front of the equation. And 2 oxygens instead of 1. 😫🤯😱

[@kiyantv5040]

People here because of school^^^

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wautah

[@DelcieloCapital]

fooken legendddd

[@OggihM]

Mr matthew sent me here

[@mtine08]

Exams today

[@bhantihajarika5669]

Bagwan bachha le aj exam he meri jiasa galti koi mat karna

[@calum8172]

What’s Mr

[@pxstelrxses1361]

Relative atomic mass