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However, the liquid density is very low compared to other common fuels. Once liquefied, it can be maintained as a liquid for some time in thermally insulated containers. [6] There are two spin isomers of hydrogen; whereas room temperature hydrogen is mostly orthohydrogen, liquid hydrogen consists of 99.79% parahydrogen and 0.21% orthohydrogen. [5]
The gaseous phase of water is known as water vapor (or steam). Visible steam and clouds are formed from minute droplets of water suspended in the air. Water also forms a supercritical fluid. The critical temperature is 647 K and the critical pressure is 22.064 MPa. In nature, this only rarely occurs in extremely hostile conditions.
The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. In liquid form, H 2 O is also called "water" at standard temperature and pressure. Because Earth's environment is relatively close to water's triple point, water exists on Earth as a solid, a liquid, and a gas.
This is a distinct physical state which exists at low temperature, and the resistivity increases discontinuously to a finite value at a sharply-defined transition temperature for each superconductor. [12] A superconductor also excludes all magnetic fields from its interior, a phenomenon known as the Meissner effect or perfect diamagnetism. [12]
For room-temperature liquids, the right-hand side is about 10 −14 seconds, which generally means that time-dependent processes involving translational motion can be described classically. [54] At extremely low temperatures, even the macroscopic behavior of certain liquids deviates from classical mechanics. Notable examples are hydrogen and ...
Chain-melted state: Metals, such as potassium, at high temperature and pressure, present properties of both a solid and liquid. Wigner crystal: a crystalline phase of low-density electrons. Hexatic state, a state of matter that is between the solid and the isotropic liquid phases in two dimensional systems of particles. Ferroics
At room temperature or warmer, equilibrium hydrogen gas contains about 25% of the para form and 75% of the ortho form. [30] The ortho form is an excited state, having higher energy than the para form by 1.455 kJ/mol, [31] and it converts to the para form over the course of several minutes when cooled to low temperature. [32]
Water is an inorganic compound with the chemical formula H 2 O.It is a transparent, tasteless, odorless, [c] and nearly colorless chemical substance.It is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent [20]).