Warning: Sodium hydroxide is corrosive. Copper sulfate is toxic. Wear gloves when handling them. Greetings fellow nerds. In this video we’re going to do the famous chemical garden experiment. It’s a nice beautiful experiment and can even be kept as decoration or centerpiece if you wish. Now apologies for the weird filming location and lighting. As you know i don’t have a lab at the moment so i’m filming this in my bathroom. Seriously, my toilet is over there. If you hear any flushing sounds you’ll know why. Anyway, don’t look at this as a disadvantage, at least now i’m forced to do more homemade chemistry that anyone can do even without a lab. Although you will need a digital scale. So let’s get started. First get a tall glass container with at least one liter capacity we add 60g of silicon dioxide based cat litter. This is often called crystal cat litter or silica gel cat litter. Do not use the more common clay based cat litter. Clay will not work for this. We specifically need silicon dioxide. I find cat litter the best for this experiment, even better than sand. Now add in 30g of sodium hydroxide. This is available as drain opener and is often sold as crystal lye. Give it a quick shake. Now for the dangerous part, add in 100mL of water and shake. The water will dissolve the sodium hydroxide and react with the silicon dioxide to produce sodium silicate. The reaction generates a lot of heat and may even boil. We need that heat to drive the reaction forward. Keep shaking to dissolve as much of the silicon dioxide cat litter as possible. The steam generated isn’t toxic, but i do not recommend inhaling it. Now if a lot of it remains then you can leave it overnight and shake again in the morning. I’m going to do that and skip ahead. And here we are. There is still a small amount of cat litter but this acceptable. Now we add an additional 800mL of water to dilute the mixture and get it to the right concentration to make our chemical garden. We didn’t add all the water earlier because we needed high concentrations to make the sodium silicate. But for the chemical garden experiment we need low concentrations. Anyway, shake it until it’s thoroughly mixed. Now get some copper sulfate crystals. Copper sulfate is available as root killer formula or snail killer for ponds. Also get large crystals that are about a centimeter big. If your are too small or a powder then you made need to recrystallize your own copper sulfate. Now carefully drop the crystals in so they spread out. While there is nothing bad about them all bunching together, the final result just looks way better if you spread the crystals out. You can move the crystals with a stick or a straw if necessary. You have several minutes before anything significant happens. Let me adjust the container for a better view. Now all we do is wait. Over the course of a day the crystals will seem to sprout and grow. It almost looks like a stalagmite although the mechanism is completely different. What’s happening is quite fascinating. As soon as you drop the crystals in, the surface of the copper sulfate dissolves but immediately reacts with the sodium silicate solution to form solid copper silicate. This coats the crystal so it’s encased in a layer of copper silicate. But the silicate layer isn’t perfectly impervious or rigid, water can still diffuse in. As it diffuses in it dissolves the copper sulfate underneath and forms a solution. This concentrated solution pushes out as the water continues to diffuse in and increases in pressure. The copper silicate membrane bulges out but eventually it can’t contain the pressure and ruptures. The copper sulfate solution rushes out of the rupture and instantly reacts with sodium silicate solution to form another layer of copper silicate. This layer is newer and weaker so as the pressure builds again it too will rupture and the process repeats. This gives the appearance of a growing structure. It grows upward because the density of the copper sulfate solution is lower than that of the sodium silicate. Now this is rather slow so don’t expect it to be too dramatic. I’m actually timelapsing this over eight hours. An interesting historical footnote about this process is that early scientists a century or so in the past studied this extensively when they were beginning the exploration of the chemical underpinnings of life. The chemical garden honestly looked like a living process made from entirely non-living chemicals. So they thought there was some connection or analogous science going on. We now know that this has absolutely nothing to do with the complex organic chemistry of carbon bonds, lipid bilayers, proteins and DNA. But nonetheless, although it was a dead end, the chemical garden was an honest effort to get started. Anyway, here we are 8 hours later. We got some pretty good growth and even some changes in color as the copper silicates form small amounts of copper hydroxide and copper oxide. Now the growth is still going but my camera ran out of memory space. So i’m going to come back in a couple of days to see the final stage. And here are about two days later. You can see some impressive growth and it looks like we have a chemical forest rather than just a garden. I can see why early chemists thought this might have something to do with life. It resembles seagrass. Now if you want you can drop in more crystals if you feel there is still room. The sodium silicate solution is still active. Alternatively, you can also dump out the solution and do the experiment again in a different container. But I should warn you that the original garden is very fragile and will break up so if you want to preserve it you should leave it in the original solution. As you can see a lot of it is broken. Anyway, you can reuse the solution and drop in new copper sulfate crystals to do it again. Let me try and get a better view. And let me zoom in to get a macro shot of the growth. There we go. Now the solution does get weaker every time you use it so I only recommend a couple of uses before starting all over again. As you can see the growth is not as well formed but it’s still working. The chemical garden experiment was popular for many decades and sold as kits and even as toys. I remember buying a kit when I was younger. But concerns over safety have made them all but disappear. One particular problem is that the chemical salts, like these copper sulfate crystals, look just like candy. I’m sure you can imagine the accidents that resulted with young children. Now you might be wondering if you can use different chemical salts. And indeed you can. Here is one using cobalt chloride. This was a test run so it looks all bad since i tossed in all kinds of substances but it did work. You can use just any metal salt as long as it forms insoluble silicates. So you won’t be able to use sodium chloride or potassium salts as their silicates are soluble. Personally I recommend copper sulfate as it’s the easiest to get and produces the best looking growth. So that was the chemical garden experiment made using crystal cat litter, drain opener, and root killer. Thanks for watching. Special thank you to all of my supporters on patreon for making these science videos possible with their donations and their direction. If you are not currently a patron, but like to support the continued production of science videos like this one, then check out my patreon page here or in the video description. I really appreciate any and all support.