Chemical Equilibria and Reaction Quotients

Many chemical reactions don't just go one way, they go forwards and backwards. Once there is balance between the two, this is an equilibrium. And we need to be able to predict how much stuff there will be at equilibrium! Get ready to bust out those ICE boxes, folks.
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Covered most of the things of the topic in short time. This is good one.

[@retroarthanadi1626]

Hi Professor Dave, for the answer 0.12, I know in the table it's 2x so 2 * 0.06 would be 0.12, but the question asks for NO2 while in the table is the concentration for 2NO2 so shouldn't that be divided by 2 again and get 0.6 (NO2) as the final answer? Sorry for my bad english

[@reddragonemperor1623]

No , if 1 mole of n2o4 gives 2 mole of no2 so in total moles of no2 will be 2 moles not 1 mole

[@hofnihangula1816]

@@reddragonemperor1623 Bruv Im getting the same anwser but my X is 0.949 Isthere a problem. pls help

[@tez0999]

Thank you sir

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Professor Dave I love you

[@ProfessorDaveExplains]

i love you too!

[@modernscientist5465]

SUBSCRIBED The channel well explained sir....

[@hadeelallaw7848]

How did you put the concentration in mole?

[@ProfessorDaveExplains]

a mole is a number, not a unit of concentration

[@hadeelallaw7848]

@@ProfessorDaveExplains thank you for your explanation

[@devverma8412]

Thank you for teaching me jesus

[@phyuhninnaing380]

Thank you so much Professor Dave. The most unique thing about your lessons is...there is always a comprehension check test at the end of it. It makes a significant difference because most of the time, I have been watching all online lessons and I thought I understood, but when it comes to problems, I dont know how to use the theory I learnt. But now, with your videos, I can learn what kind of problems will come up for the theory I learnt which is very helpful. Thanks again.

[@ProfessorDaveExplains]

happy to help!

[@jimmytorres7232]

Thank you professor Dave for a very clear explanations about Thermodynamics and Chemical Equilibrium. I really appreciate it.

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I swear my chem professor is the worst at teaching

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blueberry yup and so as mine ... she’s the reason why i lost my key to future tho 💔

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No , mine is worse 🙂💔

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My chemistry teacher doesn't even teach us...

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My science teacher too..

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My chem teacher is completely under qualified.

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I’ve learned here in 6 minutes what I’ve been confused about for the past week. Thank you!

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It's always crazy to see just how quickly and thoroughly you can teach a whole concept in under 10 minutes. Amazing work

[@corey5454]

Wish it was a step by step process on how you solved for x in the last example.

[@themathguy5492]

It's in there, look at the previous example for help. Remember products over reactants

[@michaeljessica6374]

Please I still don't understand

[@babatundejoseph4415]

Already confused he used 4x instead of 2x pls can someone explain that side to me,I mean the last place

[@SphokuhleNdlovu]

(2X)^2= 4X^2 I hope you understand 🥲

[@iz_latte]

the exponent applies to both 2 and x so you get the product of 2^2 and x^2 = 4(x^2)

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U really explained very well.... 🇮🇳loads of love frm India

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Got a exam in 30 mins! Let’s hope Dave can save me from failing!

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@Mari Christofidou i passes with a decent grade!

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Wish me luck, I'll be doing tha same :')

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god bless this man you make chem endurable :,)

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Literally saving my life! Thanks so much

[@nicholaspoh4916]

May I know how you solve 0.126=x/0.10-2x? If possible, please show me step by step. Thank you Dave.

[@Zero-th2sc]

just cross multiply, the rest is just algebra manipulation

[@arvojustice]

I think that “subjects taught at a university level” is just a nice way to say things taught poorly by people who don’t want to teach.

[@ProfessorDaveExplains]

Um, what?

[@arvojustice]

Joke lol, my prof spent a fair amount of time today complaining about how he needs to teach after someone asked him to further explain this concept

[@neaeanblue]

Hello, On the checking comprehension why is [NO2]^2 changed to 4x^2 and not 2x^2? Is it because of the equation give?

[@ProfessorDaveExplains]

don't forget that when you do (2x)^2 the exponent operates on both the 2 and the x! so it becomes (2^2)(x^2) or 4x^2

[@neaeanblue]

Professor Dave Explains Thank you. Your videos are great!

[@kmarie1102]

I love that you are able to present concepts in a way that makes sense. A lot of professors jump into certain topics without really letting us know the importance of it, what its used for in or why we should care. You have an amazing gift of giving students the AHA moment and making things click! Thank you doesn't suffice for the work you do. Much love 🤗

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Wow this is very helpful. I've been staring at my Icebox Questions for hours. Thanks Dave💪🏽

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Thank you so much for explaining this concept. You are superb and amazing

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Bruuhh im on a professor dave marathon since online classes got me confused as heck and now i have a test and i barely know what a chemical formula is xD

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2:55 "Simple no? ...no

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[@aychaabs5024]

in 2:52 why did he only take away one (0.135) form the 1m instead of two? shouldn't the product be 0.730 as both reactants have 0.135. someone please explain

[@nevilkumara9038]

I'm from Sri Lanka.... The way you teach is really amazing..... Really it covers our A/L syllabus.thank you so much

[@theepicsalad9576]

I've never had an online tutor that has been the pillar of my chemistry marks. LMAO

[@1NikkiPink1]

Hi professor Dave. Thanks again for the great videos. Quick question on the checking comprehension. Did you multiply both sides by negative one to get to the quadratic form? When I multiply both sides by the denominator, I get the opposites for addition and subtraction.

[@ProfessorDaveExplains]

nope i just brought the left side to the right side! if you have 0.036 - 0.36x and you bring it to the other side to be with 4x^2, you have to subtract the number and add the x term so the signs reverse.

[@1NikkiPink1]

wow lol that was silly of me. Thanks for taking the time to answer such a mundane question! You are awesome!

[@EarlSweatshirt1096]

@@ProfessorDaveExplains this was also helpful to me, thank you

[@Ramusacol]

Profesor Dave, your on line classes are helpful even to some teachers and professors. Your explanation is absolutely understandable. Thanks

[@dr.bucci.]

Thank you very much this is extremely helpful. However, I am confused about how you got 4x^2 in the numerator when solving for X using the Equilibrium Constant Expression. Could you explain why we use 4x^2 instead of 2x^2? Thanks again!

[@ProfessorDaveExplains]

you have to square the 2 as well!

[@mrpickles1]

@@ProfessorDaveExplains Yeah i was super confused as to why the 2 remained AS WELL as having it raised to a power of 2. I thought the coefficient was what became the power.

[@aswaths4184]

Why can't we talk about the concentration of solids? Isn't concentration of solids equal to the number of moles of the solids present in 1 liter of the solution?

[@ProfessorDaveExplains]

But that wouldn't be a solid. When a solid dissolves it is a solute in the aqueous phase.

[@aswaths4184]

Oh ok thank you for the quick reply!

[@gouripandey4148]

Sir plz can you in another video of yours.."The addition of inert gas at equilibrium at : (a) Constant pressure (b) Constant volume...... I would be really thankful if you could help.😃

[@saintofchelseathomascarlyl5713]

i thought this new semester was going to be a headache now im good thanks dude

[@elzika739]

You haven’t explain how to solve for x

[@draugami]

In that example, x was given in the problem. 0.135 moles was produced. From that, you can deduce how many moles of reactant is left.

[@jyfelisilda8194]

Can I ask something? What if the K is greater than 1 but the product is a solid. Is it still product favored?

[@shashankshekhar1266]

Hey Professor Christ. Suppose If I take the equation of PCl5 PCl3 and Cl2 at 1:44 . Now, since Kc(equilibrium constant) is independent of initial concentration, I can take Z molar solution and should still get the same answer. But if initial concentration is Z and degree of dissociation is a , Kc comes out to be (Za)^2/(Z-Za) => Za^2/(1-a). That is, it depends on Z(initial concentration) . PLEASE HELP.

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Professor Dave , you have doctoral degree of all subjects as you explain physics chemistry biology and other things , or you are speaker.

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Actually thought I knew what I was doing until I watched this, now I'm completely lost haha

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Are u sure about your thought 🤣🤣

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Thank you sooooooo much Professor Dave, you are a real life saver, Love from India::::))))

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Bro where are you from

[@dennishandfield4369]

I would love to learn more about balance being stillness please!

[@MohammadAlMarzooqi-hh5hj]

why is it 4x squared and not 2x squared, in the comprehension check?

[@StephenJM94]

These steps aren't shown in the video's solution, but remember that everything inside the brackets/parentheses raised to the power of 2 is squared: [NO2] = 2x [NO2]² = [2x]² [2x]² = 4x²

[@MohammadAlMarzooqi-hh5hj]

@@StephenJM94 thank you

[@matheusgodoy8288]

Hi Professor Dave, how are you? Well, I just wanna ask you (please) to put subtitles in yours videos, at least in English. I know that some of those have it, but some don't (like this one).

[@ProfessorDaveExplains]

+Matheus Eduardo Domingues de Godoy i certainly will! i normally do have subtitles for everything, i am just a little behind on the new content. thanks for watching!

[@matheusgodoy8288]

Ah, ok thanks Professor!

[@Summer-jw7qw]

i have a question about the example, how did you professor Dave get 0.036 from? And why is it 4x^2?

[@ProfessorDaveExplains]

(2x)^2 = 4x^2, and the rest is just from doing some algebra. check out my algebra tutorials if its confusing!

[@raghulbalaji8226]

Your way of teaching is awesome 👌 sir. I like it. I am from India.

[@RhynocerousRex]

Another way I learned this is with a Homophone. Kanye Quest. if Kanye Quest. Always helped me remember it because I could never remember if it was Q then K or K then Q.

[@bihararathnayake4056]

WOW SIR.... GREAT SIMPLE EXPLANATION. THANK YOU

[@manu-mm4pc]

How do you find 0.135 moles for x?

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I wish my teacher teaches like you

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Grazie.

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even the lower order students would top by hearing his lectures so innovative hats off!!!

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not me :/

[@mimiMie-ys3lx]

So can someone explain the math, how did he get 0.080?

[@tahaazalai1995]

proffesor Dave you really exactly teacher who should all students rely on your lessons shorts and clear and convincing. i really appreciate you professor , but only few topics i didn't get on your lessons. that's Nervous system. CNS and PNS

[@birdyboy4490]

if qc is higher than kc, the reaction proceeds in the reverse direction to achieve chemical equilibrium. So am i right to say that at the start of the reaction, the initial concentration of product is high while the reactant is 0?

[@ProfessorDaveExplains]

well you could start the reaction from anywhere, all products, all reactants, some combination, and it will go in one direction or the other until it equilibrates

[@birdyboy4490]

@@ProfessorDaveExplains oh alright thank you

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Thank you so much!!! My chemistry "professor" was literally gaslighting us wtf, he taught us the entire process wrong and then told us the answer keys are given wrong in our book. 🤢🤢 Can't believe such people exist in this world Anyway, thanks again professor dave!

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this is great but.. im still so losttttt

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I have a test in a few days and you're saving my life dude

[@Emilia-wh6oz]

Hi, do someone know why in the formula "C" is raised to "c", "D" to "d" and so on? and why C is multiplied by D and A by B, before division.

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I belong to pakistan,and aced my examinations in flying colours!thats just because of prof dave!tysm!✨

[@kookshow86]

oh man, I'm stuck trying to figure out how you got x=0.010 , my algebra is rusty af

[@dari4638]

the only actual meaning of Kc is whether it greater than 1, less than 1 or equal to 1, because we can multiply all of the coefficients of a given reaction by any positive number and the new Kc for that reaction will be equal to the old one raised to the power of said positive number. what I'm trying to say is that there's no one scale for Kc so we can't really compare it to any number other than 1. why do I seem to be the only person that's gotten to that conclusion?

[@realizejust415]

question Equilibrium does mean the rate of the forward reaction is equal to the rate of the reverse reaction Equilibrium constant = forward reaction / backward reaction If equal, it means one Why does the reaction reach the equilibrium state? The equilibrium constant is not one?

[@linakalilo735]

Good day sir... I honestly do not understand how one gets the change and equilibrium amount using the ICE I am lost

[@sanjaythiagarajan8349]

You crazy man you saved my life

[@deepaksingh-ip2dv]

Thx sir love from india 😘😘😘😘

[@victormakari3812]

why are we using Kc.....i thought we use partial pressures when talking about gaseous elements (Kp)

[@richardkeilig4062]

Prof Dave is the best.

[@trevornixon642]

Absolutely.

[@emmaebbasta6028]

I didn't really understood the difference between Kc and Q, since the formula is actually the same

[@aggudude624]

Understood everything very well, except i failed at the math part, but i guess that's on my own shortcomings

[@candidranger9110]

I love my chemistry C.I. but man it's easier for me to understand what he's saying if he provided us more visuals.

[@arjaydeleon5996]

Can somebody explain to me how did he got X at 5:45?

[@ProfessorDaveExplains]

the math is laid out step by step, was there one step in particular that is confusing?

[@sultandpippa]

@@ProfessorDaveExplains I am not sure I understand either, it seemed as though it went straight from 0.126 to just knowing what x was? I feel like I missed something

[@Aayesha739]

Ya made this one go easy too....Lucky to have prof like ya 😊😇

[@homesweetcooking939]

not understand still, you should explain it more slowly and throughly...

[@farmahdin]

Why coefficients are squared?

[@pinkman9927]

hello, prof. dave, i would like to ask which equilibrium constant(Kp or Kc) we should consider when a reaction involves GAS and LIQUID and even SOLID in the same reaction

[@ProfessorDaveExplains]

ah good question, i suppose Kc? that's just a general equilibrium constant.

[@pinkman9927]

well in thermodynamics we have K=e^-DeltaG/RT now which 'K' is that one!? these are actually ignore in our ordinary books. i dont understand why are these little things are ignored.

[@preethamjee6022]

It's Kc

[@coolkid9770]

I LUV YOU SOO MUCH!!!!! thank you thank you thank you!!!!! nobody told me anything about the ICE thing i had to assume everything myself...but thanks to this, im confident to answer these types of questions!!! THANK YOU THANKYOU THANKYOUU

[@Illzy]

Howd you solve for X?

[@esraamohamed9930]

thanks a lot from my heart

[@chillandp7648]

But i want according to chemistry that at static equilibrium will the concentrations will be same of both reactants and products

[@ProfessorDaveExplains]

it doesn't happen in chemistry, equilibria are always dynamic.

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he knows lot about science stuff professor dave explains!!

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Thank You so much for explaining this concept so easily and mess free.

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A hundred page unit summarized in one 7min video ur the best

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I love your explanations ! wish you all the best.......

[@Goyam0_0]

Even the first sentence of this video made so much more sense that what my teacher has taught

[@mrscherryhuggypoinks9438]

In 2:06, what do you mean by “In this case, all stoichiometric coefficients are one”? Can you explain that in layman’s term? :( And what are stoichiometric coefficients? :((( Sorry for the dumb questions.

[@ProfessorDaveExplains]

check out my tutorials on stoichiometry, the mole, balancing equations, etc. from earlier in the general chemistry series! they are necessary for understanding these concepts.

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YOU ARE THE BEST BROOOOOOOOO

[@mjtolentino9294]

your video really help in my review for board exam. thankyou so much. requesting for difficult example in problem solving on analytical chemistry.

[@نيومي-ع5ح]

Perfect except for Q

[@emmaebbasta6028]

idem