Water and Oil Do Mix – On Saturn‘s Moon Titan,Scientists Find
PASADENA,CA – In a discovery challenging fundamental chemistry principles,scientists have found that substances typically considered incompatible - like oil and water - can combine too form stable structures on Saturn’s moon Titan. A team from NASA and Chalmers University of Technology demonstrated that hydrogen cyanide, a polar molecule, can form co-crystals with nonpolar hydrocarbons like methane and ethane, conditions mirroring Titan’s surface.
The finding, published in the journal PNAS, upends the conventional “like dissolves like” rule of chemistry, where polar molecules attract other polar molecules and repel nonpolar ones. On Earth, this principle dictates that oil and water remain separate. Though, the extreme cold and unique atmospheric conditions on Titan allow for an exception.
Researchers replicated Titan’s surroundings – approximately minus 183 degrees Celsius – by combining methane, ethane, and hydrogen cyanide. Spectroscopic analysis revealed that the nonpolar methane and ethane molecules intercalated, or squeezed into, the crystal structure of the polar hydrogen cyanide, creating a novel co-crystal.
“This goes against the rule in chemistry,’like dissolves like,’ which basically means it is indeed unfeasible to combine these polar and nonpolar substances,” explained Martin Rahm,lead author of the study from Chalmers University of Technology,in a statement.
Titan’s atmosphere is rich in nitrogen and simple hydrocarbon compounds, including methane and ethane, which cycle through local weather systems analogous to Earth’s water cycle.The discovery suggests that similar exotic solid structures may exist elsewhere in the Solar system and offers insights into the potential for complex chemistry in environments previously thought inhospitable to such interactions. The team further modeled hundreds of potential co-crystal structures to confirm their stability under Titan’s conditions.
