Between the states under which matter can appear, gases are probably the state that most easily admits mixing between different substances.
Practically all gases can be combined unlimitedly, of course conditioned by some chemical and physical aspects and fundamentally related to the safety of the user who handles them. Like the different types of mixtures that are established between substances, gas mixtures they also have properties that are unique to them.
The study of fizzy mixes is usually as useful as that of gases in their pure state: the same knowledge about the air that is present in the atmosphere would be impossible if it were not for knowledge about ratios and behaviors of bound gases.
In this way, it is essential to know some characteristics of gas mixtures as is the property of the partial pressure (that exerted by each one of the gases within the mixture) and that of the mole fraction (relation between the number of moles of the component with that of the total of the mixture). The moles express the proportion and the amount of gas in the substance.
The Dalton's Law is the one that states that the total pressure of a gas mixture is equal to the sum of the individual gases that participate in it: this is subject, of course, to the gases not reacting with each other. It should be remembered that the partial pressure is understood here as the one that each of the gases would exert if it were found alone in the same container and under the same temperature conditions.
The corollary of both equations is that knowing the proportion between the partial and total pressure (the mole fraction of the gas), the partial pressure can be determined, a data that is usually difficult to find but very useful.
One of the central elements in mixtures is that of concentration, which can be expressed in different units. In this sense, it is the most common to use the amount of substance in ppm (parts per million), since this unit is independent of pressure and temperature. Otherwise, the normal pressure and temperature conditions (CNPT), which give a normal state to 0 degrees Celsius of temperature, and 1013 hectopascals of pressure.
In some cases, the use of gas combinations requires an intended level of concentration, but note that a real one is actually produced: in this order of things, the level of tolerance with respect to the intended theoretical concentration becomes very important. . Usually it oscillates 5%, but it changes according to the content, type and number of components.
See also: Mixtures of gases with solids
The following list contains gas mixtures, specifying the elements that appear in the mixture:
- Air (mixture of 21% oxygen and 79% nitrogen, plus other gases in small proportions)
- Cronigón (mixture of 99% argon and 1% oxygen)
- Trimix (mixture of oxygen and helium, with a ratio of 1/5)
- Deodorant spray
- Neon, argon and xenon mix
- Blend of 85% methane, 9% ethane, 4% propone and 2% butane.
- Sulfur hexafluoride and air
- Aerosol insecticide
- Air and helium
- Nitrox (air mixture, oxygen enriched)
