Fuel Cells | GCSE Chemistry (Triple)

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[00:00:00]Fuel cells work slightly differently to how chemical cells work. This is everything you need to know. Let's make it really simple. If you're new here, I'm Joseph aka Mr. Wells. If you have missed my previous video about chemical cells, give that one a watch before you watch this. So, a fuel cell can produce a voltage continuously so long as they are supplied with a constant supply of fuel and oxygen from the air. That fuel is oxidized electrochemically and that means that this whole reaction can take place at a lower temperature. And unlike with combustion, the energy released is not thermal energy, it instead is electrical energy. Now, the common one and the one on your spec is hydrogen-oxygen fuel cells. Here's a bit more about those. In a hydrogen-oxygen fuel cell, hydrogen and oxygen are used to produce water as the only product and that's a really good thing. Now, at the negative electrode, this happens.

[00:00:51]Hydrogen gas is combined with hydroxide ions to produce water and release electrons. Losing electrons, we can say the hydrogen is oxidized. Over at the positive electrode, the oxygen, along with some water and the electrons, come together to produce hydroxide ions again. That oxygen gaining electrons, we can say it's being reduced. And with these two equations happening together, the overall reaction is very simply just hydrogen plus oxygen to give water. Now, this topic often incorporates an evaluate question, so you might have to sum up the pros and cons of each of the different types of chemical cells and fuel cells. Let's start with an alkaline cell. These are great because they're very cheap to make. They're very cheap to manufacture. However, remember they're not rechargeable. So, once they're flat, they may just end up somewhere like in landfill. It's really hard to re-extract those metals and recycle them. Next one, rechargeable chemical cells. Obvious pro for this one, they're rechargeable. So, once they run out, you can recharge them and use them many a time. However, these ones cost more money to manufacture. So, compared with the alkaline cells, they're more expensive. And then finally, the hydrogen oxygen fuel cell.

[00:02:00]These ones are great because they're quite easy to maintain. There's no moving parts. They're very small in size, and water is the only product.

[00:02:07]That's brilliant. Cons for this one, hydrogen oxygen fuel cells are very expensive to produce. They also require that constant supply of the hydrogen gas as the fuel. And hydrogen gas is flammable. Remember your squeaky pop test. Spacecraft are the ones that often make use of the hydrogen oxygen fuel cells. They're very expensive, yes, but they're brilliant because they produce water that then the astronauts are able to make use of themselves. We then have a sort of complete cycle that takes place because these spacecraft, they also have solar cells. Solar cells, of course, convert light energy into electricity. So, we can then use that electricity produced from the solar cells to do electrolysis of water and split the H2O into more hydrogen and oxygen to be used in the fuel cell. So, the whole time that spacecraft is up in space, when it's light, we can make sure we make use of the solar cells. And when we hit a region of darkness, say we go behind the Earth with the sun