Ideal Gases

We define ideal gases, classify them, and go through their characteristics. Additionally, its general properties and what they provide.

ideal gases
Many actual gases exhibit ideal gas-like characteristics.

What are ideal gases?

A hypothetical or theoretical gas is what is referred to as an ideal gas, and it is made up of particles that move randomly and without interacting with one another.

The relationship between its kinetic energy and temperature is straightforward. The molecules that make up it collides with one another and with the container or containers in elastic collisions, which preserve momentum and kinetic energy.

Is about a practical idea that may be examined using statistical mechanics and a condensed equation of state called the “ideal gas law.”

At least qualitatively, many of the real gases that are known in chemistry behave like an ideal gas at room temperature and pressure. This enables them to be investigated as ideal gases within a set of logical constraints.

The ideal gas model, however, frequently fails at low temperatures and high pressures because the gas particles interact strongly under these circumstances and the intermolecular gaps cannot be regarded as a vacuum.

However, this model works well for light gases like molecular hydrogen (H2) and some heavy gases like carbon dioxide, but not for heavy gases like refrigerant gases (CO2).

See also: Fluids

Types of ideal gases

According to the kind of physical method they have selected for their approach, ideal gases can be divided into three fundamental categories:

  • Maxwell–Boltzmann ideal gas. It can also be a quantum ideal gas or a classical thermodynamic ideal gas, depending on the physical method used to study it.
  • Bose quantum ideal gas. It consists of bosons, a kind of elementary particles. For instance, a sort of boson is photons, which are particles that carry electromagnetic energy like visible light.
  • Quantum Fermi ideal gas. Fermions, another kind of elementary particle, make up its structure. For instance, atoms’ constituent particle, the electron, is a form of fermion.

Properties of ideal gases

Some of the main properties of ideal gases are:

  • The number of molecules in them is constant.
  • Their molecules are not subject to any forces of attraction or repulsion.
  • They cannot switch between phases (gas-liquid, gas-solid).
  • At the same pressure and temperature, ideal gas molecules consistently occupy the same volume.

Ideal gas law

ideal gases
The behavior of most real gases can be predicted by the ideal gas law.

The four factors of pressure, volume, temperature, and the number of moles of gas are used to characterize the state of a quantity of gaseous matter.

The ideal gas law, which foretells the behavior of the majority of real gases at room temperature and pressure, is the ideal mathematical relationship between these variables.

According to the equation that captures this law, one of the four variables may be computed using the information of the other three:

ideal gases

P stands for the gas’s pressure, V for its volume, n for its number of moles (which must not change), R for the ideal gas constant (8.314472 J/molK), and T for the gas’s temperature.

If a gas obeys this law, it can be treated as if it were ideal.

Additionally, this law combines the Boyle, Gay-Lussac, Charles, and Avogadro laws.

Boyle’s Law

ideal gases
At constant temperature, the volume of a gas varies inversely proportionally to the pressure.

The scientist Robert Boyle established the relationship between pressure and volume in gases through a series of experiments he conducted in the seventeenth century utilizing gases and liquids.

This inspired him to come up with his law, which states that “if the temperature is constant, the volume of a gas varies inversely with the pressure.”

The following equation represents this for ideal gases:

ideal gases

Where P1 and V1 are the initial pressure and volume of the gas, while P2 and V2 are the final pressure and volume.

Gay-Lussac’s law

This law explains that the pressure of a mass of gas whose volume remains constant is directly proportional to its temperature (expressed in kelvins). It was raised by Joseph Louis Gay-Lussac in 1802.

For ideal gases, this law is represented by the equation:
ideal gases

Where P1 and V1 represent the gas’s initial pressure and volume, and P2 and V2 represent its final pressure and volume.

Charles law

This law, which defines the precisely proportionate relationship between temperature and volume of a gas under specific pressure, was made possible by the studies of the French scientist Jacques Charles in 1787.

This law can be expressed mathematically as follows:

ideal gases

Where V1 and T1 represent the gas’s volume and initial temperature and V2 and T2, its volume and final temperature, respectively.

Avogadro’s Law

Ideal Gases Explained Ideas
Two gases with equal volumes also have equal numbers of particles.

Amadeo Avogadro came up with the law in 1811 when he realized that:

“Equal volumes of different gaseous substances, measured under the same conditions of pressure and temperature, contain the same number of molecules.”

What is the ideal gas model for?

The idea of an ideal gas emerged from the need to comprehend how these frequently utilized industrial fluids perform.

Instead of building a model specifically for each type of gas, an ideal formulation is employed, which is a simplified model that can be used to study most gases.

Ideal and non-ideal gases

hydrogen - ideal gases
Under normal circumstances, hydrogen is closer to an ideal gas.

Non-ideal gases are those that actually exist in the real world and whose behavior does not always follow what is predicted by the ideal gas law.

This is especially true for heavy gases like water vapor, whose behavior cannot resemble that of an ideal gas due to the significant interactions between molecules. In contrast, under normal pressure and temperature settings, other light gases (like hydrogen) tend to be closer to an ideal gas.

Continue with: Noble Gases

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