Thanks for watching! Sure, I would love answer any of your questions. Firstly, lets get something straight. An electrolytic cell is not a battery. But a battery and an electrolytic cell are both electrochemical cells. A battery is one type of electrochemical cell in which a spontaneous Redox reaction allows you to generate an electricity source. On the other hand, an electrolytic cell allows a non-spontaneous Redox reaction to take place with the help of a battery. With that said:
1) The purpose of a battery is NOT to power just any redox reaction. Its to power a non-spontaneous Redox reaction. So in this case, we use a spontaneous redox reaction to power a non-spontaneous redox reaction. The purpose of the battery is to create a movement of electrons that flows to the left. This means that to close the circuit, the electrons from right electrode must circle back to the point of origin. Otherwise, we would have an open circuit, which means electrons would not flow.
We will have a tad bit of hydroxide ions present in the mixture, which will be oxidized at the other end by the following reaction: 2OH- + -> (0.5)O2 + H2O + 2e-. The sulfate ion actually does not take part in the reaction and remains in the mixture. Why? Well because the oxidation potential for the above mentioned reaction is higher. Note that the concentration copper sulfate remains constant in the mixture.
That is exactly right! Looks to be like you got it! : ) I have a few other lectures on galvanic cells and concentration cells. Check them out and let me know if you have more questions!
2) Electrons naturally flow from negative to positive side. In a galvanic cell, electrons flow naturally from the anode to the cathode. That means, the anode must be negative and the cathode must be positive.
A battery is an electrochemical cell in which electrons spontaneously run from the anode to the cathode. They run between the wire connecting the two electrodes. Imagine cutting the wire and connecting the two ends to the electrolytic cell in such a way, that the electrons will run in the reverse direction in the electrolytic cell.
You seem to be following some type of formula.. Try thinking about it logically, you will see that you cannot get a positive value for an electrolytic cell. The reaction shown above is not spontaneous, which means it cannot have a positive voltage. Since oxidation of chlorine takes place in the anode and reduction of sodium takes place in the cathode, you simply add the two negative numbers up. And you get - 4.072. Remember, in an electrolytic cell, you are using a battery to power the reaction.
Hey Louis, Thank you. And yes, you are correct. The external source is a your regular voltaic cell. Which anode are you referring to? The anode in the electrolytic cell or the voltaic cell?
Voltage is an intensive property, which means it does not depend on the amount present. Therefore, you do not multiply it by the coefficients. On the other hand, enthalpy is an extensive property and that is why you always multiply enthalpy. Hope that helped :)
Thanks for the response! I was referring to the anode for the voltaic cell. I always get the negatives and positives for voltaic cells/electrolytic cells mixed up.
1.36 is the reduction potential of chlorine, so you have to flip the number to get chlorine's oxidation potential (since in this reaction it is being oxidized). Also, you have to take the sum of the oxidation and reduction potentials to find the voltage. The video explains that the voltage can't be positive because electrolytic cells deal with nonspontaneous (unfavorable) reactions, which would indicate a negative value for E
Good video! I like that you point out where the oxidation and reduction reactions are occurring. As a minor aside, it might be helpful to add an annotation to the video to show the battery's orientation (left is - and right side the + ). It seems a bit arbitrary that the electrons are moving to the left without that info, and could create the misconception that electrons always go to the left when an electrolytic cell is drawn. Just a thought.
Here's a case where you really shouldn't "PANIC" because that mnemonic is not accurate here because the cathode and anode are switched . I think the naming convention of anode and cathode could be greatly improved if we instead called anodes "oxodes" and cathodes "redodes" as the anode is where oxidation occurs and the cathode is where reduction occurs. This is true for any kind of cell, galvanic, electrolytic or otherwise.
Yes, your explanation helped a lot. It seems to me that you're saying the battery (galvanic cell) powers the flow of electrons in an electrolytic cell by reversing the flow of electrons so that an otherwise non-spontaneous redox reaction can occur. And for # 2, are you saying that the - sign becomes a + sign b/c in an electrolytic cell's anode b/c the electrons do not flow naturally from the anode but instead have to be "forced out" by the battery.
Thank you very much for this video! I have a quick question though. For the external battery source, is that battery a voltaic cell? Would the anode be the negative end where the electrons are leaving?
Im a bit confused. I am pretty sure that in voltaic/galvanic cells, the cathode is negative and the anode is positive, but you state the opposite. Electrons flow from anode -> cathode, therefore cathode is always negative, and anode is always positives because electrons are leaving. Can you clarify?
No he's right. The total voltage is the SUM of the oxidation and reduction potentials, so it's: Erxn = Eoxidation + Ereduction Erxn = -2.714 + (-1.358) = -2.714 - 1.358 = -4.072V
So if you have to bars of Cu(s) in a solution of CuSO4 and apply the current, the Cu+ ions would be attracted to the end with the negative charge (cation) and be reduced into Cu(s) therefore being left behind on the Cu(s) all ready there? What happens to the SO4?
This video is very helpful. Thanks a lot. I just wonder if you can clear some of my confusion. 1)If the battery is the electricity source in this kind of cell, then why are electrons being taken from the anode? I thought that the purpose of the battery was to power the redox reactions, so shouldn't the battery provide the electrons? 2)Why is the anode positive for electrolytic cells & negative for galvanic cells? I thought it should + in both cells b/c oxidation always occurs at the anode.
you say its reverse of voltaic cells, but in your voltaic cells video electrons also flow from a + charged anode to a negative charged cathode, so i dont understand. i mean in the diagrams you show it flowing diferently but essentially they both flow in the same direction
Everything is the same between voltaic and electrolytic cells except the charges of the anode and the cathode and the overall concept about how this is for reactant favored reactions.
If you are referring to the electrolytic cell, then the anode will be positive. Why? Well you said it yourself. Since electrons are leaving, that end will be electron deficient. Simple as that. Less electrons means more positive. The other end is negative because it gains the electrons.
very informative video, but what is the force that causes the electones to get sucked up the through the anode so it creates a positive charge around the electrode. we know chloride doesn't want to give up its electrons. is it the force of the battery?
theburthope lumby The wire and battery is the fastest way for the electrons to travel towards the positive source ( Na^+). And well Cl doesn’t like to lose electrons, Cl ion with a 1 minus charge is much easier. At least that is how I understand it, I could be wrong though.
quick question: since E cell = cathode - anode, wouldn't E cell = (-2.714) - (-1.358) = -1.356? E cell would still be negative, indicating an electrolytic cell, but would the emf but a different value than -4.07V?
sorry, i saw my mistake, i was supposed to flip the -1.358 and make it positive, thereby the equation should be -2.714 - 1.358 which would make it equal = -4.07V
you arent taking into account which of the electron potentials is in reference to oxidation and reductions. electron potential of cell = red electron potential + ox electron potential -4.072V= -2.714V + (-1.358)
THANK YOU SO MUCH FOR THE VIDEO A quick question, since Na is 1-, why is two electrons required instead of 1? And why is there two moles of Na and Cl in the half equation?
You're welcome! I think you mean Na is +1.. But anyways, the reason there are two moles of sodium atom is because one of the products of this reaction is a diatomic chlorine molecule. Since it is diatomic, it is composed of two chlorine atoms.. so to balance the equation out, we put a two in front of the sodium. Hope that helped!
E_cell = E_cathode - E_anode is only used if you are too lazy to flip one of the half-reactions from reduction to oxidation. That is, the negative sign is implemented to take that flipping process into consideration. However, I use the equation E_cell = E_cathode + E_anode because I like to first determine which is the oxidation and which is the reduction. When I determine the potential for the oxidation, I simply negative the sign of the cell voltage of that particular atom and then add up the two potentials. So lets say that you are not comfortable with my method, you can still use your equation and get the right answer: E_cathode - E_anode = - 2.714V - (+1.358V) = -4.072 V .. So you still get the correct answer. Basically, the way they teach it in schools and in textbooks is kind of annoying because they make you memorize the equation with the negative sign but never really explain what the negative sign is for. The negative sign is used to flip the equation from the reduction to oxidation equation.
Thanks for such a good explanation, but plz can you make a video on why do electrons flow from +ve to -ve terminal, although electrons have -ve charge :|
How did you know the electrons are going to flow the way they did? Why were you able to just say immediately "therefore electrons are going to flow this way"
Thanks for watching! Sure, I would love answer any of your questions.
Firstly, lets get something straight. An electrolytic cell is not a battery. But a battery and an electrolytic cell are both electrochemical cells. A battery is one type of electrochemical cell in which a spontaneous Redox reaction allows you to generate an electricity source. On the other hand, an electrolytic cell allows a non-spontaneous Redox reaction to take place with the help of a battery. With that said:
1) The purpose of a battery is NOT to power just any redox reaction. Its to power a non-spontaneous Redox reaction. So in this case, we use a spontaneous redox reaction to power a non-spontaneous redox reaction. The purpose of the battery is to create a movement of electrons that flows to the left. This means that to close the circuit, the electrons from right electrode must circle back to the point of origin. Otherwise, we would have an open circuit, which means electrons would not flow.
dude killer short lecture, to the point, and with all the information needed.
Love the clear explanations. Great for reviewing before my test!
We will have a tad bit of hydroxide ions present in the mixture, which will be oxidized at the other end by the following reaction: 2OH- + -> (0.5)O2 + H2O + 2e-. The sulfate ion actually does not take part in the reaction and remains in the mixture. Why? Well because the oxidation potential for the above mentioned reaction is higher. Note that the concentration copper sulfate remains constant in the mixture.
That is exactly right! Looks to be like you got it! : )
I have a few other lectures on galvanic cells and concentration cells. Check them out and let me know if you have more questions!
2) Electrons naturally flow from negative to positive side. In a galvanic cell, electrons flow naturally from the anode to the cathode. That means, the anode must be negative and the cathode must be positive.
I know it has been a while since this video was made, but your content is always incredibly easy to follow along with and quite informative. Thanks!
Awesome! good to see you found it helpful!
A battery is an electrochemical cell in which electrons spontaneously run from the anode to the cathode. They run between the wire connecting the two electrodes. Imagine cutting the wire and connecting the two ends to the electrolytic cell in such a way, that the electrons will run in the reverse direction in the electrolytic cell.
Hope that helped!
great! happy to hear that!
thank you!! taking the MCAT in a month and still didn't understand this until this video!
Awesome Sarah! Best of luck on the MCAT! Its such a long exam!
You seem to be following some type of formula.. Try thinking about it logically, you will see that you cannot get a positive value for an electrolytic cell. The reaction shown above is not spontaneous, which means it cannot have a positive voltage. Since oxidation of chlorine takes place in the anode and reduction of sodium takes place in the cathode, you simply add the two negative numbers up. And you get - 4.072. Remember, in an electrolytic cell, you are using a battery to power the reaction.
Hey Louis,
Thank you. And yes, you are correct. The external source is a your regular voltaic cell. Which anode are you referring to? The anode in the electrolytic cell or the voltaic cell?
The anode in the voltaic cell is negative. Electrons will flow from the anode to the positively charge cathode.
Thanks! Glad to hear it helped! :D
Voltage is an intensive property, which means it does not depend on the amount present. Therefore, you do not multiply it by the coefficients. On the other hand, enthalpy is an extensive property and that is why you always multiply enthalpy. Hope that helped :)
Thank you. I appreciate that.
This helped a lot, made the whole process really easy to understand, thank you so much :)
Thank you so much!! This just saved my chemistry lab mark!
Thanks motuza,
You are absolutely correct with your reasoning! :)
Thanks for the response! I was referring to the anode for the voltaic cell. I always get the negatives and positives for voltaic cells/electrolytic cells mixed up.
1.36 is the reduction potential of chlorine, so you have to flip the number to get chlorine's oxidation potential (since in this reaction it is being oxidized).
Also, you have to take the sum of the oxidation and reduction potentials to find the voltage. The video explains that the voltage can't be positive because electrolytic cells deal with nonspontaneous (unfavorable) reactions, which would indicate a negative value for E
Thanks man, i missed college and this vid cleared my concepts, yay!
Excellent video!!! Thanks so much! You're like a billion times better than my teacher.
Good video! I like that you point out where the oxidation and reduction reactions are occurring.
As a minor aside, it might be helpful to add an annotation to the video to show the battery's orientation (left is - and right side the + ). It seems a bit arbitrary that the electrons are moving to the left without that info, and could create the misconception that electrons always go to the left when an electrolytic cell is drawn. Just a thought.
Good
no way it's this easy. Haha i love your videos, concise and straight to the point. Thanks a million!
Mohammed Kamareddine :-) you're welcome! glad you picked up the concept that quickly!
Fantastic explanation. I am studying for medical school and this helped a lot. Thanks!
Thank you :)
absolutely great with clear explanation thank you
Here's a case where you really shouldn't "PANIC" because that mnemonic is not accurate here because the cathode and anode are switched . I think the naming convention of anode and cathode could be greatly improved if we instead called anodes "oxodes" and cathodes "redodes" as the anode is where oxidation occurs and the cathode is where reduction occurs. This is true for any kind of cell, galvanic, electrolytic or otherwise.
Excellent video - very helpful for studying for the MCAT.
great vid! thanks
Yes, your explanation helped a lot. It seems to me that you're saying the battery (galvanic cell) powers the flow of electrons in an electrolytic cell by reversing the flow of electrons so that an otherwise non-spontaneous redox reaction can occur.
And for # 2, are you saying that the - sign becomes a + sign b/c in an electrolytic cell's anode b/c the electrons do not flow naturally from the anode but instead have to be "forced out" by the battery.
Thanks man
helped a lot
Hope that helped :)
lol thanks! glad to hear that :)
You got a video!!!
Thank you so much sir!! I love your lecture videos it helped me a lot I will be taking chemistry board exam on october wish me well :)
Way better than anything I could ever learn in class. Thank you soooo much!!!
Thats awesome! Make sure to check out my site, tons of material there in a much more organized way!
Thanks fpr the help
great video
thanks,you're amazing :)
your awesomeness is awesome
you guys have very simple syllabus
thank YOU!
Thank you very much for this video! I have a quick question though. For the external battery source, is that battery a voltaic cell? Would the anode be the negative end where the electrons are leaving?
I love you! Thanks for this video! Also I love your accent :)
Yes, its correct. Check the comments below. Someone already made that remark.
Im a bit confused. I am pretty sure that in voltaic/galvanic cells, the cathode is negative and the anode is positive, but you state the opposite. Electrons flow from anode -> cathode, therefore cathode is always negative, and anode is always positives because electrons are leaving. Can you clarify?
do you multiply the electron potential by whatever coefficient is needed to balance charges of the half reactions or do you leave as is?
thank you somuch 🤗
No he's right. The total voltage is the SUM of the oxidation and reduction potentials, so it's:
Erxn = Eoxidation + Ereduction
Erxn = -2.714 + (-1.358) = -2.714 - 1.358 = -4.072V
So if you have to bars of Cu(s) in a solution of CuSO4 and apply the current, the Cu+ ions would be attracted to the end with the negative charge (cation) and be reduced into Cu(s) therefore being left behind on the Cu(s) all ready there? What happens to the SO4?
Hey.
That formula works under certain conditions. Check the comments below. The video has the correct calculation.
What do you mean?
This video is very helpful. Thanks a lot. I just wonder if you can clear some of my
confusion.
1)If the battery is the electricity source in this kind of cell, then why are electrons being taken from the anode? I thought that the purpose of the battery was to power the redox reactions, so shouldn't the battery provide the electrons?
2)Why is the anode positive for electrolytic cells & negative for galvanic cells? I thought it should + in both cells b/c oxidation always occurs at the anode.
KING
you say its reverse of voltaic cells, but in your voltaic cells video electrons also flow from a + charged anode to a negative charged cathode, so i dont understand. i mean in the diagrams you show it flowing diferently but essentially they both flow in the same direction
Everything is the same between voltaic and electrolytic cells except the charges of the anode and the cathode and the overall concept about how this is for reactant favored reactions.
how to decide the type of electrodes, same or different? from what series ?
Why does the addition of a battery cause the electrons to flow in the opposite direction?
If you are referring to the electrolytic cell, then the anode will be positive. Why? Well you said it yourself. Since electrons are leaving, that end will be electron deficient. Simple as that. Less electrons means more positive. The other end is negative because it gains the electrons.
Does the Na stick to the cathode or does it just hang around it?
Yes, it becomes electroplated to the cathode (negative electrode) hence the Na (s) meaning it is forming a solid.
very informative video, but what is the force that causes the electones to get sucked up the through the anode so it creates a positive charge around the electrode. we know chloride doesn't want to give up its electrons. is it the force of the battery?
theburthope lumby The wire and battery is the fastest way for the electrons to travel towards the positive source ( Na^+). And well Cl doesn’t like to lose electrons, Cl ion with a 1 minus charge is much easier. At least that is how I understand it, I could be wrong though.
Can you make a video on product of electrolysis? Thanks.
hey man..great videos. could you turn it into a playlist for chemistry?
also while you are at it..could you cover decomposition voltage and polarisation?
Good
Very nice video
quick question:
since E cell = cathode - anode, wouldn't E cell = (-2.714) - (-1.358) = -1.356?
E cell would still be negative, indicating an electrolytic cell, but would the emf but a different value than -4.07V?
sorry, i saw my mistake, i was supposed to flip the -1.358 and make it positive, thereby the equation should be -2.714 - 1.358 which would make it equal = -4.07V
you're so cute.
btw, you helped me pass my final.
Thank you! :-p and congratulations on passing the final!
you arent taking into account which of the electron potentials is in reference to oxidation and reductions.
electron potential of cell = red electron potential + ox electron potential
-4.072V= -2.714V + (-1.358)
I thing it should be 1.36 rather than -4.072 is that correct??\
THANK YOU SO MUCH FOR THE VIDEO
A quick question, since Na is 1-, why is two electrons required instead of 1?
And why is there two moles of Na and Cl in the half equation?
You're welcome!
I think you mean Na is +1.. But anyways, the reason there are two moles of sodium atom is because one of the products of this reaction is a diatomic chlorine molecule. Since it is diatomic, it is composed of two chlorine atoms.. so to balance the equation out, we put a two in front of the sodium. Hope that helped!
yes it's all clear now
thanks!
Ivysaaur Beans
Great!
i didnt understand why the E-cell is -4.072 ...
isnt it supposed to be E cathode - E anode?
E_cell = E_cathode - E_anode is only used if you are too lazy to flip one of the half-reactions from reduction to oxidation. That is, the negative sign is implemented to take that flipping process into consideration. However, I use the equation E_cell = E_cathode + E_anode because I like to first determine which is the oxidation and which is the reduction. When I determine the potential for the oxidation, I simply negative the sign of the cell voltage of that particular atom and then add up the two potentials. So lets say that you are not comfortable with my method, you can still use your equation and get the right answer: E_cathode - E_anode = - 2.714V - (+1.358V) = -4.072 V .. So you still get the correct answer. Basically, the way they teach it in schools and in textbooks is kind of annoying because they make you memorize the equation with the negative sign but never really explain what the negative sign is for. The negative sign is used to flip the equation from the reduction to oxidation equation.
woah you rock
thanks :)
Sorry if I have this totally wrong.It's all very new to me.
Get him to 1k likes
E0+ - E0- = 1,36 - (-2,71) = +4,07 V
Thanks for such a good explanation, but plz can you make a video on why do electrons flow from +ve to -ve terminal, although electrons have -ve charge :|
tanker 2399 I am no longer working on physics.
This is a chemistry question. Plz tell me. =(
They're being forced by an outside electrical potential. There is an outside force overcoming the repulsion of similar charges.
btw ur Eo was wrong... ITs reduction - oxidation. Which would have been -2.714v - (-1.358) = -1.36V.
How did you know the electrons are going to flow the way they did? Why were you able to just say immediately "therefore electrons are going to flow this way"
I got it.. ^_^
I got it to + 4,07....
hello .
Nice explanation 😍
Sir appko hindi nahi ati 😅
Plz, I beg you. Plz reply me.
I love you! Thanks for this video! Also I love your accent :)
I love you! Thanks for this video! Also I love your accent :)
I love you! Thanks for this video! Also I love your accent :)