[Introduction Music Plays] Hi there everyone. Welcome back to Cody's Lab. So this here is 1 pound of liquid mercury. You can see it is quite small for it's weight. It's because mercury is very dense and a liquid. Many would say it's the most dense liquid on earth (at room temperature). I would say that an alloy of mercury and gold, however, would be heavier. But the question is: "How much heavier?" How much gold can I get to dissolve into mercury? You guys know that mercury will dissolve gold because this 31.1g gold bar now weighs 30.5 because I've put it into mercury before and the mercury dissolved some gold off. So, to see just how much gold the mercury will dissolve, I've produced some gold powder here. I just reduced some aurumchloric acid from solution. I'm left with a very very fine gold powder. I'm going to add just a little bit of mercury in there. I'm going to dissolve as much gold into the mercury as I can. The high surface area of the gold powder should allow me to dissolve it rather quickly. Then we're going to see how much gold the mercury picked up. So I'm adding approximately 1ml of mercury to my gold powder. And I'm doing this under water. I've got roughly a gram of gold in there. I think that'll be good. Now I'm going to let this dissolve the gold into it. It should be pretty easy. As you can see, it's already gobbled most of it up. Now, the mercury hasn't dissolved the gold. In fact, if I squeeze at it a little bit I can actually pull out bits of gold still. See, it's just kinda stuck to the gold at this point. It's not in a true solution. So what I'm gonna do now, is I'm going to let this sit in some hot water for a few hours so as to dissolve away as much gold as possible. Raising the temperature should increase the solvation rate. So, it's a couple of hours later and it appears that all of the gold particles are now coated in mercury. You can kind of see that when I move it around that the mercury is sort of clumpy in there. But I'm sure it dissolved some of it, so let's take this out, filter the gold and see just how much denser the mercury is, if at all. Ok, so I just put that mercury onto a paper towel so it will be dry. So basically I absorbed all the water off of it. Now I'm going to suck it up into this pipette here. Assuming it will suck up. Looks like it is very clumpy, as you can see. [Tap tap tap] Ok, now that I've got all of the gold sucked up, I'm going to put it into the syringe that I've got a piece of cotton stuffed into the bottom. Just like this. Now I'm going to insert the plunger and squeeze the mercury through the cotton. This should stop all the gold particles, but leave behind or let the mercury and any gold that is completely dissolved in it flow through. There it is, my lump of mercury gold amalgam. Looks like a white cylinder of metal, which is very heavy. Very interesting. See how hard that is. Feels about the hardness of chalk. Kind of looks like chalk too. Anyway, it's not what we're really interested in right now. What we're interested in is the stuff that was able to completely dissolve. So, the first thing I need to do to find the density of this mercury gold alloy is to find its volume. So I'm going to use a water displacement technique in order to figure out how much volume this metal is taking up. I got all of it. Now I'm going to put it inside this little dish. Make sure none gets left behind. I submerge it into the water. You can see I've got .865 ml of mercury here. Now all I got to do is tip it out of this to find its weight. Right about 12 grams. So let's compute the density and see if we got any denser than what mercury should be. So here is my mass of mercury, here is my volume. Dividing those 2 gives me 13.719 grams per cubic centimetre. Probably is a little bit more dense, but it's not a whole lot. It's not like 15 grams per cubic centimeter, it's still right around 13 and a half. I do have a more accurate way of measuring how much gold is in there. And that is to actually dissolve the mercury in acid and then weight the amount of gold that was dissolved into it. So to the 12 grams of mercury I'm going to add around 20ml of nitric acid. Which is an excess. The mercury will dissolve in the acid but the gold will not. While that's dissolving I've weighed out another 10g of mercury. I'm going to try something here, you see, I'm going to add a bit of zinc to the mixture. See, zinc is very soluble in mercury. I know that in a reaction with vanadium salts they use a zinc mercury amalgam which can be as much as 40% zinc. So I know zinc is highly soluble in mercury. And I also know that gold is highly soluble in zinc because the Parks process employs liquid zinc to extract gold from a lead mixture. So, let's see what happens if I dissolve some zinc into mercury and then try to dissolve the gold into that. Let's add just a little bit here. Let's say about a gram so that's roughly 10%. Ok, let's get that dissolved up and I'll add the gold. Now that I've got the zinc to the point where it's mostly mixed in with the mercury. You can still see that some solid zinc is in the mercury but it's all coated. So now let's add the gold and see if we can get this to dissolve. Yeah, still can crush it. Just mix it with the mercury and see if we can get any more gold to dissolve. So after letting this sit for a little while I'm left with something that is sort of solidified. Yeah, um. That doesn't look particularly good, does it? I might have to add a little bit more mercury. Errm, ya know. Let's try squeezing it as-is. I might be able to get this to mostly squeeze through the cloth. I got it in there. Let's see if it'll squeeze through. [Chuckle] It... it is... but slowly. It seems to be incredibly viscous but still a liquid. I am getting liquid to drop out. Once again we're going to measure its volume and then its weight to get the density. Well. And. We got. .445ml. 6.1 grams. So this is what I've come up with for the density of the zinc, gold, and mercury solution. Which is almost exactly the same as the number I got for just the mercury and gold. So I'm actually going to try something. I'm going to try measuring the density of just plain old mercury. Just so we can see if my method is flawed or not. Roughly a milliliter of mercury. Put this in the little dish. Same as I was doing before. .873 11.95 So, I actually measured the density of the mercury three times. You can see my numbers here. Thirteen point six seven, six nine, six five. So it seems to vary in the hundredths place with the method I'm using. But all of the numbers are off from the Wikipedia value of 13.534. So that means that something I'm doing, or maybe the fact that I'm doing this at room temperature rather than the optimal density of water or whatnot is causing me to be a little bit higher on the density. Ah man, I should not have written on both sides of this... It makes sense that they would be just a little higher, because it is dissolving some heavy gold into it. But look at that, that's tiny, that's not even 1%. So, here's the gold that I recovered from the first mercury dissolvation. And I notice that the gold is in the form of fairly large crystals which are far too large to have gone through the filter. So, they are definitely a result of the gold actually coming out of solution in the mercury and crystallizing as it does so. Which is really neat. Let's see just how much we've got. So that was about, I think it was, 12 grams of mercury. Let's see just how much weight that is. Alright, so that's right around 15 mg of gold in 12 grams of mercury. So that's about a milligram of gold dissolved per gram of mercury. So that's not very much, is it? That means I'm getting roughly one part per thousand. Or 0.1% gold, by weight, in the mercury. That is pretty tiny. Although, technically, it would make it heavier. Let's see if the zinc solution did any better. In this other decorative plate I have the gold that came out of the mercury that also had zinc in it. Now this stuff is markedly different in appearance. It's more of a brownish powder of super fine gold, which resembles what I started with. This tells me that rather than crystallizing from solution This gold hung on until the very end, until the acid had to rip the metal from it. That metal being zinc. My guess is that zinc formed a compound with it that was actually fairly stable. So let's put this on and see just how much gold we have. That is almost the same number. But that came from just six grams of mercury. And that had 12 mg of gold in it. That means that I had about 2 mg per milliliter. Which means I had twice as much gold. The density of the material was the same because, probably, the zinc made it a little bit lighter. But ultimately I got it to dissolve more gold by adding the zinc to it. That is cool. And I think that is because I think the zinc and the gold bond together to form a compound which is slightly more soluble in mercury. So there you go, it seems that the solubility of gold in mercury is about 0.1% But if you dissolve some zinc into it as well you can bring that up to 0.2%. Which means that, technically, the heaviest liquid that I know of so far is a mercury gold alloy. But it's only very slightly denser than just pure mercury. Also, this tells me that if I would have left this 30g gold bar in my about 100 kg of mercury for too much longer it would have completely dissolved. 100,000 grams of mercury could dissolve about 100 grams of gold. Which would be three of these. So really the only reason I was able to get it back is because it was only in the mercury for a very short amount of time. Also, one more thing, the mercury that I dissolved in the nitric acid I have right here in my waste mercury jug. Now, normally, I would treat this almost immediately so I don't have it sitting around for too long. But I think I'm actually going to make a video showing how I would go about that. So, I'm going to keep it around for a little while longer and produce that video sometime in the next few weeks or so. Anyway, hope you all enjoyed. I'll see you next time. [Music Plays]
