and raised a skeptical eyebrow

And hey! Good for you doubting stuff on the internet because photoshop is a thing

But those photos are real

Even though the molten rock isn't what's blue, it's actually combusting gases

that make the glowing blue flame

A volcanic crater on the island of Java in Indonesia called Kawah Ijen

is the best place to see this phenomenon at night

Plus, the crater also has a deadly vivid turquoise lake which is full of acid

The chemistry of the volcano causes both of these briliant colors but in two different ways

Lots of volcanoes spit up gaseous sulfur compounds

Like the Dallol Volcano in Ethiopia

So blue flames aren't unique to this crater

But Kawah Ijen happens to have spectacular amounts of sulfur,

enough to support a huge mine

The miners are after the bright yellow chunks of solidified sulfur rock

But its sulfur forms a yellow solid,

why do the sulfuric gases seeping up from the ground burn blue?

It all has to do with the chemistry of combustion

When a fuel like a sulfur compound mixes with oxygen and high enough temperatures,

a combustion reaction happens

Heat gets released and new chemicals are formed like sulfur dioxide

and the visible part of the fire is the flames

which are caused by a bunch of atoms spewing out light energy

Basically the energy from the combustion reaction

boosts the electrons in the fuel atoms to a more energetic state

When the electrons fall back to their original state,

they release all that extra energy as a photon of light

The wavelenghts of those photons determine what the flame's color is

And in the case of sulfur compounds catching fire, it's an eerie blue glow

During the day, Kawah Ijen's lava looks pretty much like the orangey-red lava of any active volcano

Although the sulfuric gases are still burning, but the bright sunlight washes the color out

But at night, sightseers flock to see all of the glowing blue flames on the rivers of molten rock

If that wasn't enough to make Kawah Ijen one of the world's weirdest places,

then there's also that turquoise acid lake

Volcanoes tend to bring all sorts of chemicals from the Earth's interior up to the surface

And in Kawah Ijen's case, there are plenty of things besides sulfur

like chlorine and a bunch of metal

In the crater lake water, the sulfur dioxide gas made by the combustion reaction

dissolves and forms sulfuric acid

And the chlorine compounds mean that there's hydrochloric acid in there too

The pH of that crater lake is no joke below 0.5

which is really really acidic, like stronger than the acid in your car battery

Needless to say don't go swimming in that death lake no matter how cool it looks

Even just measuring the pH of the water can be a really dangerous job

Acid that strong can dissolve metals no problem

And dissolved metals do something that

organic carbon containing chemicals usually don't, they turn bright colors

The color you get and whether you get a color it all has to do with the chemistry

and geometry of the metal ions floating inside the solution

Many kinds of metal ions absorb certain wavelenghts of visible light

And your eyes perceive color based on the wavelenghts of light

that are reflected off an object

So, when a metal ion absorbs one color of visible light,

you'll usually see a complementary color to the one that's absorbed

The hue that's across from it on the color wheel

If a compound absorbs light outside of the visible spectrum,

all of the visible light gets reflected and the solution looks white or clear

That's why organic chemistry might as well be called

six hundred colorless compounds and how to draw them

In organic chemistry is where all the colors are

So, the mixture of dissolved metals in Kawah Ijen's lake

is what makes the water look vividly turquoise

If the volcano were to erupt, there's a chance that the lakebed could rupture

and send that acidic "death water" cascading down the mountain to do serious harm

And because Java is so densely populated,

volcanologists keep a very very close eye on any volcanic activity in the area

So Kawah Ijen owes its incredible colors to sulfur compounds

Whether they're burning or dissolved in the lake with some metals

Those two different kinds of chemistry make this weird place

a beautiful and deadly destination

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