Water can exist in two different liquid states

The possibility that water could exist in two different liquid states was proposed approximately 30 years ago, based on results obtained from computer simulations.This counterintuitive hypothesis has been one of the most important questions in the chemistry and physics of water, and a controversial scenario since its beginnings. This is because experiments that can access the two liquid states in water have been very challenging due to the apparently unavoidable ice formation at the conditions where the two liquids should exist.

The usual "liquid" state of water that we are all familiar with corresponds to liquid water at normal temperatures (approximately 25 degrees C). However, the paper shows that water at low temperatures (approximately -63 degrees C) exists in two different liquid states, a low-density liquid at low pressures and a high-density liquid at high pressures. These two liquids have noticeably different properties and differ by 20% in density. The results imply that at appropriate conditions, water should exist as two immiscible liquids separated by a thin interface similar to the coexistence of oil and water.

The research appears in a paper published in the November 20 issue of the journal Science.

Read More: https://phys.org/news/2020-11-multiple-liquid-states.html