Behavior of gases

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Defination of Gas

A gas is a homogeneous fluid, generally of low density and low viscosity.

Gas has no definite volume but assumed the volume of any vessel which it is placed.

Specific laws that express the behavior of gases at various temperature and pressure are very important in petroleum technology.

The gases are divided into

1. Ideal (perfect) gas

2. Real ( non-ideal) gas

The properties of hydrocarbon gases are relatively simple since the parameters of pressure, Volume and temperature (PVT) can be related by a single equation.

the basics for this equation an adaptation of a combination of the classical laws of Boyle, Charles and Avogadro.

In the equation of state for an ideal gas, that is a gas in which the volume of the gas molecules is insignificant, attractive and repulsive forces between molecules are ignored, and maintain their energy when they collide with each other.

PV = C

When pressure goes up, volume goes down. When volume goes up, pressure goes down.

From the equation above, this can be derived:

P₁ V₁ = P₂ V₂ = P₃ V₃ etc.

This equation states that the product of the initial volume and pressure is equal to the product of the volume and pressure after a change in one of them under constant temperature

Ideal Gas Definition

An ideal gas is a gas whose pressure P, volume V, and temperature T are related by the ideal gas law

PV = nRT

where n is the number of moles of the gas and R is the ideal gas constant.

Ideal gases are defined as having molecules with negligible size with an average molarkinetic energy dependent only on temperature.

At low temperature, most gasesbehave enough like ideal gases that the ideal gas law can be applied to them.

List of laws that affect the behaviour of gas as follows:

The factors affects the behaviour of gases

Temperature (T)

Volume (V)

Pressure (P)

Quantity (q)

The interrelated facts of behaviour as follows:

1. The temperature is directly proportiante to volume and pressure, as the temperature decreases, the volume of the gas also decreases due to the contraction of gas molecules and When temperature increases, the volume of the gas also increases due to an expansion of gas molecules.

2. Similarly, as the temperature decreases, the pressure of the gas also decreases due to the contraction of gas molecules and when the temperature increases, the pressure of the gas also increases due to an expansion of gas molecules.

3. As the quantity decreases, pressure will also get decrease and when quantity increases than pressure also get increases.

4. For converting gas either into liquid or solid , the pressure of the gas must be very high or temperature of the gas must be very low.

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