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Turning water to metal may sound like a hidden superpower that Doctor Strange hasn’t revealed to us yet, but it actually is possible in this universe.
It might sound like magic, but under extremely high pressure, water can become a conductor—a substance that allows electrons or other particles that carry an electrical charge to move through it with ease. These pressures are not yet possible to achieve in a lab. That didn't seem to bother physicist Robert Seidel and his team of scientists, who were able to figure out another way to give H2O unreal metallic properties.
Seidel, who led a study recently published in Nature, was able to accomplish what could pass for fictional alchemy by putting an alkali metal into water. The mashup of sodium and potassium added charged particles to the water, transforming it into a silvery-golden metal that might mesmerize you if you stare at it too long.
“When an alkali metal comes into contact with water, it reacts with the water to form alkali hydroxide, hydrogen, and heat,” he told SYFY WIRE. “In an atmosphere of air or oxygen, hydrogen can get easily ignited and react with the oxygen in water to release a lot of energy. The heat release is so strong that even the metal itself starts to melt and burn.”
Super-high pressure was thought to be the only way to achieve this before because of how molecules and atoms react when exposed to it. As particles are cramped closer together, there will eventually be a threshold when the level of pressure becomes high enough to force the upper, looser molecular orbitals to overlap into a conduction band. Molecular orbitals are the result of combining orbitals in the atoms of that molecule. Electrons (which are negatively charged) in those orbitals then move around freely in the band and spark an electric current.
Alkali hydroxides can get the same result through an alternate reaction. They are made of a positively charged alkali metal ion, or cation, and negatively charged hydroxide ion, or anion. Alkali metals easily release their outer electrons, and can have explosive results when reacting with water, even without being aggravated by air or oxygen. The reason they can turn water metallic (if only for seconds) is because they let go of those outer electrons without much of a problem, just as most substances would under crushing pressure.
Electrons from alkali metals move from metal to water almost unfathomably fast. They then become solvated electrons, able to break chemical bonds and trigger intense reactions. Whatever positively charged ions are left will then enter the water, and it is the cations and anions repelling each other that causes an explosion, but what about that gold sheen?
“The golden color of the metallic water solution is due to the plasmon frequency,” said Seidel. “Plasmons are a typical metallic property caused by fluctuations of the (quasi-) free electrons. The excitation of the plasmons needs energy, which is typically in the optical or near-UV light region.”
How the water appears to us is all about what light gets absorbed, which our eyes are unable to see, and what light is reflected, which we can see. Blue and green light are absorbed by the solution while yellow, red and orange light are reflected under white light or sunlight. This is where the magic happens. It is the combination of those colors that makes it look as if water has suddenly been turned to gold.
Using optical reflection spectroscopy and synchrotron X-ray photoelectron spectroscopy, Seidel and his team were able to prove that they had indeed induced conductivity in water by detecting plasmon energy and determining how much was being produced. Plasmons have strong wavelengths. The positive charge of the cations that are left behind once anions make for the water tries to pull them back to where they were, which excites the plasmons and causes them to constantly move back and forth.
“Because plasmons are a typical metallic property, the appearance of a plasmon peak in the spectrum is outstanding proof,” Seidel said. “With synchrotron X-ray photoelectron spectroscopy, we could pinpoint the (binding) energy of the plasmons.”
This is also proof that if a phenomenon looks like magic, chances are there’s a science behind it.