GCSE Chemistry Revision "Fuel Cells" (Triple)
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- Опубліковано 13 чер 2024
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In this video, we learn how fuel cells generate electricity, looking specifically at the hydrogen fuel cell. We then compare the advantages of hydrogen fuel cells compared with rechargeable batteries.
This video is based on the AQA spec. If you are following a different exam board then you should check your specification. The Amazon link above is an affiliate link. This provides a small commission which helps to support freesciencelessons. The cost remains the same to you. If you prefer not to use this, you can search Amazon for the Freesciencelessons workbooks.
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Duracell 9V battery. commons.wikimedia.org/wiki/Fi... (Ashley Pomeroy)
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I remember in year 7, everyone sighed when the teacher played your videos. Now I'm in year 11, they're really helping with subjects I don't understand
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Sir in the exam can we give these simplified half equations or need we include hydroxide as there’s been some debate at school
Honestly well done you help so many people!
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3:05 - "Hydrogen fuel cells run on hydrogen" - Shawn, March 2017
Don't disrespect the legend.
Ok Charlotte
Thank you for being an absolute legend
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This guy needs to do a colab with vsauce
may I ask when will you do the paper 2/ have you done them (because i can't seem to find them)
Is it the actual successful collisions between the hydrogen and oxygen atoms that produces the potential difference in fuel cells?
love you. i fricking love you
Thank you my friend
Hello sir. Im a bit confused at 2:15. Why do we lose electrons at the negative electrode (cathode) when reduction occurs there?? Are there equations swapped because different sites tell me the opposite of what you are saying. Many thanks!!
@Freesciencelessons in the equation for the reaction at the negative electrode can you divide all the numbers by 2 and it would still make sense?
Yes you can do that but then it won't match the overall equation (2H2 + O2 --> 2H2O) so I personally wouldn't do it.
In the textbook it says the half equation at the negative electrode is 2H2 +4OH-=4H2O +4e-. And that at the positive electrode O2+2H20+4e-=4OH-. Are we expected to learn the ones in the video as well as these? The ones in the video seem a lot simpler
Thank you for the fuel cells
Hey thank you for this video it was really helpful! I just wanted to ask one question, on the revision guide one a labelled diagram of a fuel cell it says that the negative electrode is the anode and the positive electrode is the cathode- isn't it the other way round ??
Yes, that's correct. For electrolysis, the anode is positive and the cathode is negative but for fuel cells its the opposite.
Why isn't the half equation at the negative electrode just one hydrogen molecule changing into two hydrogen ions + 2 electrons
Why is everything double that.
It doesn't matter either way works
Thank you
watching before my mocks
I dont necessarily know why i'm watching this video as im doing the triple science exams this year in 2022 in three months and the exam board that im doing, aqa, said that fuel cells wont be in the actual gcse exams for this year due to the lockdowns of recent years that disrupted our learning so i dont need to learn this really. A whole load of stuff was taken out of physics and biology too which is good.
sir im not sure if i have to learn all the details for the edexcel paper. my book doesnt have half equations or the diagram(CGP 9-1)
This is aqa
Thanks a lot I subbed
Sir when the 4 hydrogen ions and oxygen and electrons all react to form water how are the electrons we wanted for our current supposed to be left in the cell and not gone or wasted with the water
Is hydrogen splitting in negative electrode and combining with oxygen in positive electrode to form water. Is this whole thing done to make water? I have never studied this please help I am confused.
ur a legend sir
Hello. For AQA, do we need to know in depth what happens in the fuel cell, or just what is stated in the video (if so, please can you summarise the steps we need to know?) Thanks!
.. (if someone replies ill know too)...
This is what you need to know according to the AQA specification:
Fuel cells are supplied by an external source of fuel (eg hydrogen)
and oxygen or air.
The fuel is oxidised electrochemically within the
fuel cell to produce a potential difference.
The overall reaction in a hydrogen fuel cell involves the oxidation of
hydrogen to produce water.
Hydrogen fuel cells offer a potential alternative to rechargeable cells
and batteries.
Students should be able to:
• evaluate the use of hydrogen fuel cells in comparison with
rechargeable cells and batteries
• (HT only) write the half equations for the electrode reactions
in the hydrogen fuel cell.
Legend
Is the 4H+ at the positive electrode from the electrolyte? In this case why is the positive electrode the cathode and the negative electrode the anode because it's the opposite in electrolysis? Thanks
Yeah it's meant to be like that in electrolysis the cathode is negative and the anode is postivive however in fuel cells its the opposite
Why is hydrogen gas pumped into the cathode? Shouldn't it be pumped into the anode? And how is it possible for hydrogen to lose electrons to the negative terminal?
No, this is a confusing area. In the hydrogen fuel cell, the ANODE is the negative electrode. You'll notice that I specifically do not say cathode and anode in the video. At the anode, the hydrogen is oxidised to release electrons, which is why this is the negative electrode.
Hi, I know it's been two months but I'm still confused. How is Hydrogen made to lose electrons though the electrodes aren't connected to an external circuit? What I mean to ask is how does each electrode become positively and negatively charged without being connected to a power supply?
At the negative electrode, just imagine that the hydrogen atoms are being oxidised, rather than being split.
The electrons then move from the negative electrode to the positive electrode.
The anode in this case is the source of electrons, and hence electric current. Therefore, it is considered as the negative electrode, even though oxidation occurs.
thnxs helped me...........
got my year 10 mocks coming up u have to save me man
r u in year 11 now
if i use the equations in this video in my exam (if a question like this comes up) would i get the mark ??
Yes
30 min before exam lesgoooo
Good luck. I hope that you get the grade that you wanted.
@@Freesciencelessons u literally saved me i found it ok. The absolute legend 🚀
@@MiniMahoneyYT I hope you did well!
Here the night before chem paper 1 , biology paper 1 was dodgy so I feel like they’ll put fuel cells in chem paper
sir my book states different half equations for this. At the negative electrode it is
2h^2 +40h- ---> 4h^2O+4e-
at the positive electrode there is
o^2+2h^2O+4e- -->4Oh-
CAn u explain why this is the case? many thanks
Hello:) Sorry I'm not Sir, but this is because there are two different conditions for a fuel cell - it can be in acidic conditions (like the one in the video - note the H+ ions) or alkali conditions (like the one in our textbooks - note the OH - ions). Both are correct, but AQA haven't been very decisive in telling us which one they want - so I'd recommend learning both just to be safe! Hope this helps:) Oh, and in the alkaline version there will be an electrolyte like Potassium Hydroxide providing the OH - ions.
Thanks for clearing my confusion
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Sir, i was wondering as to why in fuel cells is the anode the negative electrode and the cathode is the positive electrode? Whereas in Electrolysis it is the opposite, is it to do with the flow of electrons and electricity from the direct current?
honestly: the people who discovered fuel cells hate students and want to see them suffer in confusion
@@charleshierner2024 ikr
in the CGP AQA revision guide, it says:
H2 = 2H+ and 2e-
O2 and 4H+ and 4e- = 2H2O
I thought the hydrogens from the electrolyte and the electrons from the circuit react with the oxygen. How come in the 2nd equation it's '4H+ and 4e-' and not '2H+ and 2e-' (why did the big number change from a 2 to a 4?)
I know im soooo confused now
It’s just about balancing so it doesn’t matter what one you use
my textbook for anode says 'H2 --> 2H + 2E-. that's the same thing right ?
ye think so because there was a question on the 2018 specimen paper of that and the answer was that. but its at the negative electrode (the cathode) not the anode i think because the anode is positive (and so is hydrogen)
yes
Sir do we have to know why the Hydrogen gets reduced in the half equation? I don't get how you have formed the half equation
Similarly I don't get the half equation at the positive electrode
Do you know now?
@@someone-mv6ed Its been 2 years. This person is probably doing a levels or an apprenticeship somewhere.
@@phase0400 welp it’s the thought that counts
How does this relate to electrodes?! Very confused !
How would you do a balanced ionic equation for a hydrogen fuel cell??
Watch Dr Donnelly's balancing symbol equations video
I’m very confused is it reduction happening at the anode or the cathode or is it the other way round?
PANIC positive is anode negative is cathode
edit just realised u said this 4 years ago
Where did the half equations come from? I don’t understand how we get 4H+ and 2H2 etc
My dear knowledge seeker, that is because oxygen is a diatomic molecule meaning that it is always in groups of two, aka the total valency will be 2x2=4.Now in order to meet the demand of four electrons from the oxygen gas, the hydrogen gas needs to be doubled aka the valency in one molecule is 2 so 2x2=4, so that is exactly why you need 4 hydrogen atoms for two oxygen atoms.
Not all heores wear capes
exam tomorrow, never understood fuel cells, oh boy
Equilibrium???? That came up in my exam for this topic
Assessment tommorow :)
Always told myself to revise tomorrow. Now my chemistry exam is in 9 hours 😭
This video is good
No they're correct. The video is fine.
Freesciencelessons yea I miss interpreted the title. I apologize
Ohh now the Martian makes more sense
in the revision guide it says the negative electrode is
H2 -> 2H+ + 2e-
Not
2H2 -> 4H+ + 4e- ?
They're both correct but the second one is more correct as 2 x H2 react with 1 x O2.
Do we need to know about the reaction I'm the fuel cell at 1:22
He says you need to write them, so I would assume that it will give you part of the half equation and you can infer the rest, or you know that hydrogen loses electrons, then you know that it reacts with oxygen to produce water, so you can infer it gains electrons.
sorry for doubting you shaun
for the negative electrode, why is it not the equation H2 -> 2H+ + 2e-
It is balanced relative to the overall equation
Because oxygen and hydrogen combine
Because to balance the equation, you need to double H20 (2H20) which means that four hydrogen ions are in the products so need four electrons to be oxidised.
who else is here like 12 hours before the exam
do we need to know about alkaline fuel cells too?
Yes but not the reactions, just how they function and facts about it
bruh i'm confused. i was doing triple but my school dropped it, and yet we still have to learn some triple stuff likr this and titrations...???
Good luck tommorow everyone
thankyou hopefully I do well in gcse next year (2020).Are you a maths teacher.If so then please upload maths its a core subject and the world is in danger without your.HEEEELP Shaun Donnelly
lmao
why is is 2h2 and not just h2
Because otherwise the equation would not be balanced. 2H2O ----> 2H2 + O2
Here we go again
where did the negative and postive electrodes come from? at 1:51?
Cant believe I’m actually typing this but chemistry p1 GCSE tmr 😭
litch me this year in a few hours 😂
This was a 6 marker on AQA Triple!!
Hello, in your video you said that the negative electrode’s equation is: 2H2-> (4H+)+4e-. However, in my textbook, it says that the negative electrode’s equation is “2H2(g)+4OH-(aq)-> 4H2O(l)+4e-“. Are both of these equations the same?
In your video, you also said that the positive electrode’s equation is: O2+(4H+)+4e- -->2H2O. However, in my textbook, it says that the positive electrode’s equation is “O2(g)+2H2O(l)+4e- -> 4OH-(aq)”. So are both of these equations the same? Plss reply thank youuu
There are different types of hydrogen fuel cells and the equations that you have apply to one of the types. Can I ask which exam board you are following?
Freesciencelessons Hello sir, if it’s AQA which one would we be using as I don’t think they made it clear on the specification?
Gcse tmrw
this helped lol
CHEM paper one tomorrow
good video but its not 2H2 ----->4H+ + 4ELECTRONS it is H2------->2H+ + 2 ELECTRONS as thats more simplified isnt it?...
Hasan Javed I think it has to be double because there's 4 electrons being gained at the positive electrode and 4 hydrogen ions. It's kinda like simultaneous equations and these have to cancel each other out so you double the equation; otherwise you won't be able to get the overall equation.
Isn’t it actually 2H^2 + 4OH- -> 4H2O + 4e- because that’s what the spec says and it would work with the 4 thing
oh gosh
i'm not cramming what you on
18 minutes left
HELP WHY IS THE POSITIVE ANODE THE CATHODE HERE BUT NOT FOR ELECTROLYSIS MY HEAD OWWWW
Because in the fuel cell the current flows in the reverse direction.
Night before gang
_you called_
Taking a dig at Samsung batteries....
Safe g this gone pattern me a 9
did u get that 9 my bro
I was confused when i learnt this because i'm y10 and im learning it but it's a y11 topic
Anyone who thinks he looks like sheldon Cooper