Transcription
Hello, and welcome to the Science Fairy. In this video, I will show you how to make sulfuric acid.
First, we need the most important ingredient, and that is sulfur. I directly ordered one kilogram. I actually have no idea what to do with so much, so if you have any ideas, write it in the comments. Okay, how do we turn this into sulfuric acid? It's actually super easy. We just have to burn the sulfur. However, we have to collect the gas and dissolve it into water. When sulfur burns, it turns into sulfur dioxide. If this is dissolved into water, it turns into sulfurous acid. Then, we can turn it into sulfuric acid.
To burn the sulfur, I will put it into a reaction tube with air coming into one side and the sulfur dioxide coming out the other side. This has to be done outside because sulfur dioxide is poisonous. For the reaction tube, I just removed the bottom of a test tube. For the air, I used the aquarium air pump from my nitric acid video. And to connect everything, I used rubber stoppers and tubes connected together. It looks like this: the aquarium pump pushes air through the tube; the sulfur burns; and on the other side, you get sulfur dioxide, which goes into the bottle and dissolves into the water. While doing this, you have to wear gloves and safety glasses. Sulfur can be irritating, and the acid, well, it's acid.
I then put sulfur into the tube and heated it up. It can be a bit hard to start, and I had the problem that the sulfur is just vaporizing instead of burning, and it clogged up the tube. But after a bit, the sulfur starts burning, and the bottle fills with the white gas. But just bubbling it wasn't working too well, so I shook the bottle every time it was full of gas until all the sulfur burned away. So now we only have sulfurous acid, not sulfuric acid. The German Wikipedia says you can turn sulfurous acid (H2SO3) to sulfuric acid (H2SO4) by using air. Funny enough, the English version doesn't say that. And after bubbling in some air into the acid, I saw why it can't really work: the sulfurous acid is just an equilibrium reaction between the water and the sulfur dioxide gas, and when air is bubbled through it, the gas leaves the solution. So I need a better way, and that is hydrogen peroxide. By using the right amount, I oxidized the sulfurous acid into sulfuric acid.
All right, now you may ask how high is the concentration? I used the density to figure that out, and I had 101 grams per 100 milliliters, and that corresponds to two percent acid, which is not much. However, I probably could have dissolved more gas into the water. But there is another way to get a higher concentration, and that's by boiling it. Sulfuric acid has a boiling point of 337 degrees Celsius, so in theory, we can heat it up that much to drive off the water. First, I wanted to heat the beaker with the acid on a hot plate, but I think you can see why this would be terribly inefficient. So I just put it in the microwave. Not the best option since you put food in there as well, but as long as it's not getting too hot, only water should be coming off. At the end, I just boiled it down so the liquid can fit into my flask. With the pH paper, you can see that it's strongly acidic. I don't really have any use for it, but I just wanted to make some to explore the chemistry. So subscribe if you want to see more stuff like that, and until next time, bye.