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Reuben Cowell
06/12/2025
Chemistry
1.5.2 Chemical Cells and fuel cells
193
•
6 Dec 2025
•
Chemical and Fuel Cells: Notes on Hydrogen-Oxygen Cells
Reuben Cowell
@reubencowell
1 / 3
Chemical Cells and Batteries
Your phone, laptop, and even that old TV remote all rely on chemical cells to work. These brilliant devices are surprisingly simple - just two different metals (called electrodes) sitting in a chemical solution (the electrolyte), connected by a wire.
Here's the clever bit: the metals react differently with the electrolyte, creating a charge difference between them. When you connect them with a wire, electrons flow from one electrode to the other, and boom - you've got electricity!
The voltage you get depends on how different your two metals are. Pick metals that are really different in reactivity (like zinc and copper), and you'll get more voltage than if you choose similar ones.
Quick Tip: Think of it like a chemical see-saw - the bigger the difference between your metals, the more "unbalanced" it gets, creating more electrical energy!
How Batteries Actually Work
A single cell doesn't give you much power, so batteries are just several cells connected together in a chain (called series). It's like adding up voltages - a 2V cell plus a 2.5V cell plus a 1.5V cell gives you 6V total.
Non-rechargeable batteries (like the ones in your TV remote) die when the chemical reactants get used up. There's no way to reverse what's happened - once they're flat, they're done.
Rechargeable batteries are much smarter. Lithium-ion batteries in your phone can reverse their chemical reactions when you plug them into the wall. The external power source forces the electrons to flow backwards, essentially "undoing" the reaction that created electricity in the first place.
Real Talk: This is why your phone battery eventually stops holding charge well - after hundreds of charge cycles, the chemical reactions become less efficient at reversing themselves.
Fuel Cells: The Future of Clean Energy
Fuel cells are like the cool, environmentally-friendly cousins of regular batteries. Instead of storing chemicals inside, they continuously take in fuel (usually hydrogen) and oxygen from the air to create electricity and water.
Hydrogen-oxygen fuel cells are becoming massive in the car industry. They're cleaner than petrol cars because they only produce water as waste, and they might even beat electric cars for being green since you don't need to mine rare metals or dispose of toxic batteries.
Here's how they work: hydrogen enters at the anode and loses electrons, creating H+ ions. Meanwhile, oxygen enters at the cathode and gains those electrons. The H+ ions travel through the electrolyte to meet the oxygen, forming water. The flowing electrons create your electricity - it's a redox reaction in action.
Future Focus: Many car manufacturers are betting big on hydrogen fuel cells as the next step beyond electric vehicles, especially for lorries and buses that need to travel long distances.
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This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
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Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
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Best app on earth! no words because it’s too good
Thomas R
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Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Chemical and Fuel Cells: Notes on Hydrogen-Oxygen Cells
Reuben Cowell
@reubencowell
Ever wondered how your phone battery actually works, or why electric cars are becoming so popular? Chemical cells and fuel cells are the clever bits of chemistry that power loads of the gadgets and vehicles we use every day, turning... Show more
Chemical Cells and Batteries
Your phone, laptop, and even that old TV remote all rely on chemical cells to work. These brilliant devices are surprisingly simple - just two different metals (called electrodes) sitting in a chemical solution (the electrolyte), connected by a wire.
Here's the clever bit: the metals react differently with the electrolyte, creating a charge difference between them. When you connect them with a wire, electrons flow from one electrode to the other, and boom - you've got electricity!
The voltage you get depends on how different your two metals are. Pick metals that are really different in reactivity (like zinc and copper), and you'll get more voltage than if you choose similar ones.
Quick Tip: Think of it like a chemical see-saw - the bigger the difference between your metals, the more "unbalanced" it gets, creating more electrical energy!
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How Batteries Actually Work
A single cell doesn't give you much power, so batteries are just several cells connected together in a chain (called series). It's like adding up voltages - a 2V cell plus a 2.5V cell plus a 1.5V cell gives you 6V total.
Non-rechargeable batteries (like the ones in your TV remote) die when the chemical reactants get used up. There's no way to reverse what's happened - once they're flat, they're done.
Rechargeable batteries are much smarter. Lithium-ion batteries in your phone can reverse their chemical reactions when you plug them into the wall. The external power source forces the electrons to flow backwards, essentially "undoing" the reaction that created electricity in the first place.
Real Talk: This is why your phone battery eventually stops holding charge well - after hundreds of charge cycles, the chemical reactions become less efficient at reversing themselves.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Fuel Cells: The Future of Clean Energy
Fuel cells are like the cool, environmentally-friendly cousins of regular batteries. Instead of storing chemicals inside, they continuously take in fuel (usually hydrogen) and oxygen from the air to create electricity and water.
Hydrogen-oxygen fuel cells are becoming massive in the car industry. They're cleaner than petrol cars because they only produce water as waste, and they might even beat electric cars for being green since you don't need to mine rare metals or dispose of toxic batteries.
Here's how they work: hydrogen enters at the anode and loses electrons, creating H+ ions. Meanwhile, oxygen enters at the cathode and gains those electrons. The H+ ions travel through the electrolyte to meet the oxygen, forming water. The flowing electrons create your electricity - it's a redox reaction in action.
Future Focus: Many car manufacturers are betting big on hydrogen fuel cells as the next step beyond electric vehicles, especially for lorries and buses that need to travel long distances.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user