Gas – A State of Matter

What is the Gaseous State of Matter?

The gaseous state is that state of matter which does not possess any definite shape or size and also do not have a specific volume. It is one of the crucial states of matter that showcases various properties.

A gas can be filled inside any vessel but unlike liquid, it never takes the shape of the container in which it is filled.

Gases are a crucial part of our life or I would say that without gas we cannot assume our life on this planet earth because the air we breathe is a gas. The particles of gas are separated at a quite large distance from each other thus are able to propagate freely and hence has no fixed shape.

Let us elaborate more about Matter

Matter is anything that has some mass and is voluminous in nature. Anything that we can touch or feel is matter.

There exist basically three states of matter which are solid, liquid and gas. In our previous content, we have seen the liquid state of matter.

What is Gas?

Like we have discussed at the beginning itself that gas is a state of matter without having a specific shape or any fixed volume and is considered to be less dense than particles of solid and liquid.

We all are familiar with the diffusive nature of gases. You must be thinking that what is the reason for the diffusion of gases in space?

So basically, the particles of gases possess large kinetic energy and are present at an appreciable distance from each other. Due to having large kinetic energy, the particles move at a quite fast rate and thus while in motion collision between them occurs. This resultantly causes them to spread out till the time the particles get distributed over the complete space or vessel within which the gas is present.molecules of gas Furthermore, with the increase in the number of particles within that particular fixed space, now the overall particles will get comparatively less space than earlier to spread out and thus they will be compressed. However, as the particles have large kinetic energy thus they exert the force referred to as pressure on the interior walls of the vessel.

Thus, the pressure is one of the crucial properties of gases other than temperature and volume.

How gases appear?

Gases have no fixed shape of their own. As against, solids have a definite shape and size whereas the liquid takes the shape of the container in which that liquid is poured. Gases are quite different as their particles completely occupy any closed vessel and thus the properties possessed by the gases shows dependency on the volume of the vessel rather than the shape of the container.

Physical characteristics of Gases

The fundamental physical properties possessed by gases are as follows:

  1. Gases completely fill the vessel within which it is kept thus neither maintains their volume nor shape.
  2. Gases are highly diffusive in nature.
  3. With the increase in temperature, gases expand.
  4. Gases are of compressible nature, thus with the increase in pressure, volume decreases.
  5. The pressure exerted by gases is equal in all directions.
  6. Gases are generally colourless however gases like chlorine, fluorine, iodine , bromine and nitrogen dioxide have their characteristic colour.

Measurable parameters of Gases

Mass and volume are regarded as the two parameters that describe the behaviour of the gases.

Mass: The mass of the gas can be determined by calculating the difference between the weight of the container with gas and the weight of the container by taking the gas out.

Volume: The volume of any gas depends on the amount of its content as well as temperature and pressure. Thus, it is expressed as a function of amount, temperature and pressure.

V = f(n, T, P)

State of a Gas

The various distinguishable parameters of gas like mass, temperature, pressure, volume, etc are regarded as the state of the gas.

  • Mass: Gas is a composition of innumerable molecules each having a mass of about 10-24 g. The overall mass of the gas is the contribution of the masses of each of the molecules composing the gas.
  • Space Occupied: The space that a molecule of gas occupies is nearly 1/1000th of the overall space occupied by the gas. The rest of the space within the vessel is vacant.
  • Motion: The gaseous molecules are in random motion, above absolute zero temperature. At room temperature, the gaseous molecules (air) move at the speed of 5*104 m/sec.
  • Isotropic: The molecules of gas simultaneously move in various directions as neither attractive nor repulsive force exists between them. Due to this reason, the molecules occupy the space within the container. These offer mutual solubility because of having vacant space. Thus, their motion is similar in all directions, hence called isotropic.
  • Stationary Energy: The collision between the various molecules of the gas are elastic in nature, thus molecules exert pressure on the inner walls without loss of energy on rebounding from it. Thus, the overall energy of the system remains conserved.

The pressure is also an important parameter of gas which is measured by an instrument called a manometer.

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