Hey, Vsauce. Michael here.
And I'm in Anaheim at VidCon. I hope to see some of you here, because I
like you guys. But I can't marry all of you.
But if I did put a ring on it, what is the most precious thing you could make that ring
out of? Silver, gold, platinum.
Those are all fine, but I wanna know what is the rarest, most scarce thing on Earth
that's stable and safe to wear I could make that ring out of.
And I want it to be pure. I'm talking elemental.
Well, luckily, I recently went to the University of Nottingham, home of Periodic Videos and
experimented with some elements. First things first, zinc dissolved in mercury.
This stuff is awesome, it's dense, it's heavy, it's liquid metal.
It's cool, but even cooler is human urine. Thank you Neil.
Of course I am just kidding. This is an aqueous solution of the metal vanadium.
And when we mix vanadium in with the mercury and the zinc, the mercury helps the zinc give
electrons to the vanadium. And is it gains more and more electrons, it
changes colour. We're looking for purple.
I love shaking this, it's crazy, it's like throwing me off balance.
It's so heavy. Look at that.
Thank you electrons.
Those colours were beautiful, but vanadium
is not that rare. I wanna get something more precious.
And how about precious personally, like my dad?
He's a chemical engineer who specifically works with and has a patent concerning one
element. Sulphur.
Of course a fun thing to do with sulphur is to make it bark like a dog.
Here's what we're gonna do. We're gonna take a glass tube and fill it
with laughing gas, nitrous oxide. We're gonna pour a little bit of water into
the tube to cushion and protect the tube and then we're gonna pour in some liquid carbon
disulphide. It's very volatile and will evaporate, giving
us a mixture of gases inside this tube. Finally, I will light the top of the tube,
causing the carbon disulphide to burn. And as it burns, the temperature and pressure
in the tube will increase, causing the reaction to go faster and faster.
It'll accelerate and bark.
Wow.
And look at all the sulphur on the sides of the tube.
That reaction was fun and cool and colourful, but we're way off track here.
Even though sulphur is precious and dear to my heart, it's not that rare at all.
So let's get crazy and talk about astatine. Astatine is so rare here on Earth that we
don't even know what it looks like. If you were to try to get enough astatine
atoms together that you could see it with your own eyes, it would instantly vaporise
itself because of its radioactive heat. The fact that it's so radioactive means it
wouldn't be great as a ring, so let's move on to something a little bit more standard
and see where it takes us. Gold.
Gold, of course, is famous for its un-reactivity, which is why it's a great way to store your
wealth. If you have a lot of gold laying around, the
likelihood that it will combine with other elements and dissolve or rust or corrode is
basically zero, with the exception of some special solutions.
In particular, one discovered in 1300s with the fancy name "aqua regia."
It's made out of hydrochloric acid and nitric acid and we're about to make some right now
thanks to Neil from Periodic Videos. Of course, we're using this fume cover, because
the fumes that come off the nitric acid are quite dangerous.
It's the gas NO2 and if you inhale it, nitric acid forms in your lungs.
So instead of doing that, let's put some gold in aqua regia.
We're just gonna use this ancient priceless Egyptian relic.
Let's go ahead and try this out. As the gold dissolves, what we wind up with
in the evaporating dish is chloroauric acid. Auric coming from aurum, the Latin word for
gold, which is why gold's symbol on the periodic table is Au.
It's really sad to watch that gold dissolve away.
I wish there was a way for us to just make other things into gold.
Now I know what you're thinking. "Michael, that's alchemy."
But alchemy is quite real. In today's particle accelerators we can smash
particles together, creating elements. At the accelerator collider at GSI they can
create gold by smashing particles together at a rate of 2 million gold atoms every second.
That's pretty cool, right? Well, as you know, atoms are incredibly small.
They're so small that even though GSI can make 2 million new gold atoms every single
second, were they to leave the machine on at that rate for 50 million years they would
only produce 1 gram of gold. Gold is rare and precious and expensive.
But gold is 40% more common than iridium. And iridium is incredibly resilient.
It doesn't dissolve in aqua regia and it's not even attacked by molten metals or silicates
at high temperature, which is nice and ..., but not as pretty as cerium, which reacts at high
temperature to form beautiful little sparkles. As we continue our journey to discover the
rarest thing to make a ring out of, we've got to discuss osmium.
This stuff is so rare there's fewer than one part per billion in our Earth's crust.
But we're not done yet. Iridium and osmium are both in the platinum
family. And if you take a look at platinum, it's much
more common than both iridium and osmium, but there's something neat that I think we
should consider. Stable isotopes.
And it's one of the isotopes of platinum that will finish our story.
Platinum-190. It's a stable isotope with half-life of over
billion years that's non-reactive. It's fits all our criteria.
A ring made of the scarcest, naturally occurring stable, non-reactive thing.
So hey, it would be an awesome ring. Now, you're probably wondering, "Michael,
why did you experiment with vanadium, sulphur, gold and cerium?"
Well, here's what's interesting. Take a look at the periodic table and there's
symbols. Ta-da!
Vsauce.
And as always,
thanks for watching.