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Steam. What is it?

Steam. What is it?

Steam is a substance in the gas phase that is at a temperature lower than the critical point. Due to this characteristic, the vapor can be condensed in a liquid or a solid increasing its pressure without reducing the temperature.

That is, the vapor is a gas that can be condensed at a constant temperature, increasing the pressure. On the other hand, to convert a non-vaporous gas to liquid, it is not enough to increase the pressure, but the temperature must be lowered.

For example, water has a critical temperature of 374 ° C (647 kelvin), which is the highest temperature at which liquid water can exist.

A vapor can coexist with a liquid or solid. When the vapor coexists with a liquid or a solid, the two phases will be in equilibrium, and the gas pressure will be equal to the vapor pressure equilibrium of the liquid (or solid).

Vapor state is the state in which a gas is found when it is below the critical temperature. In the gas state the molecules that form it do not react with each other forming molecular bonds, but tend to repel each other. When repelled, the molecules adopt the shape and volume of the container that contains them and tend to separate. That is, they expand and tend to occupy all the available volume.

In the graph, vapor is the so-called gas phase, closed, by the vertical line representing the critical temperature and the blue curves (vaporization curve) and red sublimation curve, which represent the ways in which a liquid or solid matter it becomes steam. Superheated steam is the gas that is above its critical temperature but below its critical pressure.

Not to be confused with the gas concept.

Usually the word steam refers to water vapor, gas that is produced by boiling when the water is heated to 100 ° C and a pressure atmosphere, or outside this temperature of change of state, when the water is found, any temperature below the critical, at a pressure below its vapor pressure at this temperature (this is the phenomenon of evaporation).

Properties of steam

Steam refers to a gas phase at a temperature where the same substance can exist in a liquid or solid state, below the critical temperature of the substance. The term gas refers to the compressible fluid phase.

Steam is responsible for the process of cloud formation and condensation. It is used in the distillation and in the preliminary phase of gas chromatography.

The constituent molecule of a vapor has movement of vibration, rotation and translation.

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Last review: November 17, 2017

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