Gases are one of four basic material states (the other three are solid, liquid, plasma). Gases can consist of individual atoms (e. G. Rare gases), single molecules consisting of one element (e. G. Oxygen), multi-element molecules consisting of compounds (e. G. Carbon dioxide). Gas mixtures may include a variety of gaseous substances such as air. A significant difference between gases and liquids and solids is the large gap between gas particles. This interval makes it difficult to detect colourless gases. Gases are fluids like liquids: they can flow, they can transform. Unlike liquids, gases can be compressed. If there is no restriction (container or force field), the gas can spread, its size is unlimited and it is not fixed. Atoms or molecules of gaseous substances can move freely among themselves。
The characteristics of the gas are between liquid and plasma, the temperature of the gas does not exceed that of the plasma, and the lower temperature of the gas, which is reduced to a condensed quark gas, is also receiving increasing attention. High-density atomic gases cool to very low temperatures and can be classified according to their statistical characteristics as botanical and pyro-gases, and other phase-by-phase lists。
Element gases
The chemical elements that are gas molecules under standard conditions are hydrogen (h2), nitrogen (n2), oxygen (o2) and two halogens, fluorine (f2) and chlorine (cl2). There are also rare gases of single atoms: helium (he), ne, aluminum (ar), krypton (kr), zirconium (x) and radon (rn). One
Physical nature
Because most gases are difficult to observe directly, they are often described through their four physical properties or macro properties: pressure, volume, number of particles (expressed by chemists in molars) and temperature. These four attributes have been repeatedly observed by many scientists (e. G. Robert boyle, jacques charlie, john dalton, joseph louis gay-lussack, amodyo avogadro, etc.) through different gases and different devices. Their careful study eventually led to the ideal gas law that describes the mathematical relationship of these properties. One
Macro properties
When gases are observed, reference or length scales are generally indicated. The larger length scale corresponds to the macro properties of the gas or the overall view. The range (notable size) must contain at least a large number of gas particles. Statistical analysis of gases so sampled gives the average properties of all gas particles in the sample (e. G. Speed, temperature, pressure, etc.). On the contrary, a smaller reference length scale corresponds to the perception of the micro properties or particle level of the gas。
Pressure
Main entry: pressure
In formulae, "p" or "p" is commonly used to denote gas pressure in units that are usually pascal in the international unit system。
When describing a gas with a packaging, the pressure (or absolute pressure) is the force applied by the unit area of the gas on the surface of the packaging, within which the gas particle may be considered to move in straight lines until it collides with other molecules or the wall of the container. In the event of a collision with the wall of the container, the change in the amount of the gas particle's kinetics in a unit time is the force of the gas acting on the packaging. During the collision, only the rate of the gas particle's velocity of the wall of the vertical packaging will vary, and the amount of its kinetics will not change if the gas particle is moving along the wall of the container. The pressure on the wall of the container is therefore the average of the changes in the dynamics of the gas particles that interact with the wall of the container。
Pressures are all gas particles that impact on the wall of the container, and the force produced is divided by the value behind the total area of the wall。
Temperature
"t" is commonly used in formulas to indicate the temperature of the gas and is often kelvin (k) in the international unit system。
The rate of gas particles is proportional to their absolute temperature. In the film to the right, when balloons are placed in liquid nitrogen, the size of the balloons is reduced by lower temperatures and slower gas particles. The temperature of the gas system is associated with the movement of particles (atoms or molecules) in it. In statistical mechanics, temperature can represent the mean kinetic energy stored in particles. The way energy is stored is related to the freedom of particles. When a gas particle collides, the particle produces a motion of flat, rotation or vibration, which increases its kinetic energy. Conversely, molecules in solids are not able to move or rotate in crystal cells and only increase temperature by vibration. Heated gases, because of their continued collision with packagings or other gas particles, have a large velocity distribution and can be described in the maxwell-bernzmann distribution, assuming that the gas particles are close to the ideal gas in a state close to the thermodynamic equilibrium。
Bien
Main entry: apparel
See: volume (thermal)
A "v" is commonly used in formulas to denote a gas phase, often in a cubic metre (m/kg) of the international unit system. This means that "v" is commonly used in the volume of gases, often in cubic metres (m)。
In describing the thermodynamic properties, a distinction is made between the intrinsic and the expansive nature. Volumes associated with the quantity (volume or mass) of the gas are referred to as expansive, and quantities not related to the quantity (volume or mass) of the gas are referred to as internal. The size of the mass gas in units of mass when the relative is internal and thermally balanced. The volume of gases is related to the volume of gases and is therefore expansive。
The contrast between solid state and liquid changes slightly with pressure or temperature, but when pressure or temperature changes, the contrast of gas changes significantly, and when the pressure is halved, the comparison of gas is doubled, so the gas is compressed。
Density
Main entry: density
The formula is often used to indicate gas density in units of kg per cubic metre (kg/m3) in the international unit system, which is the bottom of the scale。
Since gas molecules often move in containers, their mass is generally expressed in density. Density is the mass of the unit volume and the penultimate of the frame. The range of changes in gas density is large ... Because when pressure or volume are limited, gas molecules can be closer together. The change in density is compressible, the density and pressure of the gas and the temperature are state variables and the change in the process follows the laws of thermodynamics. For static gases, the density of the gas is the same throughout the packaging. Density is a measure, and if a fixed mass gas, density is inversely proportional to the size of the packaging. Two
Micro property molecular motion theory
Main entry: molecular motion theory
Molecular motion theory provides an intrinsic perspective on the macro properties of gases by considering the composition and movement of gas particles。
Brown movement
The random movement of gas particles, starting with different gases above and below, can eventually be seen to be spreading
Main entry: brown movement
Brown moves are mathematical models that describe the random movement of particles in fluids. The pink and green particles in the right animation describe the way the gas moves. Three
See
Solid melted liquid gas gas gas gas
Solid condensate liquid plumes liquid plumes
Gaseous platinum plume solid plume gas
The content of this term is contributed by:
Assistant professor zhang zhang zhou
