# Ideal and Real Gases

Gas is a funny type of matter. Unlike solids or liquids, gases don't have a fixed volume and instead take the shape of whatever container they're in. But did you know that not all gases behave the same way? That's where ideal gases come in. Ideal gases are theoretical gases that behave exactly as predicted under all conditions. This makes it easier to study gases and figure out how they work.

The Ideal Gas Law is a formula that explains the behavior of ideal gases. It says that for an ideal gas, pressure times volume is always equal to the number of gas molecules times a constant (called the Gas Constant) times temperature. All gases that exist in the environment are Real Gases, and they follow the Ideal Gas Law only under certain conditions. While ideal gas is a hypothetical gas that follows the Ideal Gas Law at all conditions of temperature and pressure, real gases only behave like ideal gases under conditions of high temperature and low pressure. When it comes to describing gases, the Ideal Gas Law is just one of many equations used to explain how gases behave. So, next time you're studying gases, remember that ideal and real gases are two different things, and there's a lot to learn about how gases behave.

## Properties of Ideal and Real Gases

### Ideal Gas and Real Gas: How Are They Different?

Ideal gases are theoretical gases that follow gas laws at all temperatures and pressures. They are made up of solid, spherical particles that don't attract or repel each other. The motion of the gas molecules is completely random, and they travel in a straight line until they hit another particle or the container wall. The collision of these particles with each other or the wall is completely elastic, which means the kinetic energy of the gas remains constant.

However, any gas that exists in reality is a real gas. Real gases can never be perfectly ideal because atoms and molecules will always have some forces of attraction or repulsion between them, and they occupy some volume. Under some conditions, the size of atoms or molecules can no longer be considered negligible as compared to the distance between the particles. Generally, gases behave more like ideal gases at high temperatures and low pressures, while they deviate from ideal gas behavior at low temperatures or high pressures. At standard temperature and pressure, some gases such as Hydrogen, Oxygen, Nitrogen, Helium, and Neon show behavior close to that of ideal gases. Since there are no intermolecular forces of attraction between particles of an ideal gas, it can never be liquefied. Conversely, real gases can be liquefied under certain conditions, as intermolecular forces of attraction will overcome the kinetic energy of the particles and form a liquid.

## Ideal Gas vs Real Gas: Similarities, Differences, and Examples

Although ideal and real gases have many differences, they also have some similarities. Both are gases and are made up of particles that move randomly due to collisions with surrounding particles. This is called Brownian Motion.

While ideal gases are theoretical, some real gases come close to ideal gas behavior under certain conditions. For example, Hydrogen, Oxygen, Nitrogen, Helium, and Neon show behavior that is very close to that of ideal gases at standard temperature and pressure.

All gases found in the environment are real gases, even Hydrogen, Oxygen, and Nitrogen. However, they behave like real gases at low temperatures and high pressures, which is why it's possible to liquefy them. Most real gases behave like ideal gases under conditions of high temperature and low pressure. High pressure is when the particles are forced to be in close proximity, such as in CNG gas cylinders in cars or oxygen cylinders for scuba diving. The kinetic energy of gas particles is directly proportional to temperature. Higher temperature means higher kinetic energy of the gas particles, which minimizes the effect of intermolecular forces on the movement of the particles. At room temperature, gas particles have enough kinetic energy to overcome intermolecular forces and behave like ideal gases. In summary, while ideal and real gases have many differences, they also have some similarities. Understanding the ideal behavior of real gases can help us better understand how gases behave in different conditions.

## Deviation of Gases from Ideal Gas Behaviour

### Conditions of Ideal Gas Behaviour

As the container size is small, the particles are forced to be in close proximity. This means that the intermolecular forces of attraction or repulsion between particles become significant, even at high temperature. This reduces the speed at which the particles collide with the container, reducing the pressure. However, the ideal gas equation predicts that the pressure should be high due to the high temperature. This deviation from the ideal gas behavior is due to the fact that the size of the molecules is not negligible compared to the size of the container. This means that the particles are no longer behaving like point-sized particles and the average distance between particles is no longer much larger than the size of the molecules. The behavior of the gas can no longer be accurately predicted by the ideal gas equation, and therefore, the gas is said to be deviated from ideal gas behavior.

In summary, the behavior of real gases can deviate from ideal gas behavior under certain conditions. This includes low temperature, high pressure, and when the size of the molecules is not negligible compared to the size of the container. Understanding these deviations is important in various fields, including chemical engineering and materials science.

Additionally, Helium behaves the most like an ideal gas amongst real gases due to its monatomic nature and small size. On the other hand, deviations from ideal gas behavior can occur when the size of the molecules is not negligible compared to the size of the container, as well as under conditions of low temperature or high pressure. In such cases, the intermolecular forces of attraction/repulsion between particles become significant, and the behavior of the gas can no longer be accurately predicted by the ideal gas equation. Understanding these deviations is important in various fields, including chemical engineering and materials science.

## Ideal and Real Gases

What is ideal and real gases?

Ideal gas is a hypothetical gas  which follows Ideal Gas Law at all conditions of temperature and pressure.Real gases are those which exist in the environment. They follow Ideal Gas Law only under conditions of high temperature and low pressure.

What are examples of ideal and real gases?

Gases like Hydrogen, Oxygen, Nitrogen, Helium Neon behave like ideal gas under conditions of Standard Temperature and Pressure (0oC, 1bar).

When does a real gas behave like and ideal gases?

A real gas behaves like an ideal gas under conditions of high temperature and low pressure.

What is the condition temperature and pressure for ideal gases?

Volume of ideal gas at certain temperature and pressure will be determined by the formulaV = nRT/PVolume of a real gas will be more than that predicted by this formula because unlike ideal gas particles, real gas atoms/molecules have volume and occupy  space.

Why do gases exert pressure on any container they are contained in?

Particles of a gas are always in random motion. They are continuously colliding with other particles and with the walls of the container. When particles collide with the container, they exert force on it. Pressure of a gas is the net force of all particles on the container walls, per unit area of the walls.

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