# What is the order of the mean free path in gases?

## What is the order of the mean free path in gases?

Mean free path of an air molecule is of the order of 10-6m.

### What is the path of air molecules in order )?

Pathway of air: nasal cavities (or oral cavity) > pharynx > trachea > primary bronchi (right & left) > secondary bronchi > tertiary bronchi > bronchioles > alveoli (site of gas exchange)

What does mean free path depend on?

The mean free path equation depends upon the temperature and pressure as well as the molecular diameter.

What is meant by mean free path of a gas molecule derive an expression for it on which factors does it depend?

The mean free path depends on the following factors: i. Density – Density increases when the number of molecules are increased or the volume is decreased. Other factors – Mean free path can be affected indirectly by pressure, temperature and other factors which affect density.

## What is mean free path derive equation of mean free path?

Therefore, the number of molecule in the cylinder will be N/V multiplied by the volume of cylinder i.e.πd2vt. As such, the derivation of mean free path can take place as follows, λ = length of path during the time t/number of collision in time r ≈ \frac{vt}{\pi d^{2}vt\frac{N}{V}} = \frac{1}{\pi d^{2}\frac{N}{V}}

### What is the path taken by air molecules into and through the nose?

Air enters through the nose (and sometimes the mouth), moves through the nasal cavity, the pharynx, the larynx, enters the trachea, moves through the bronchi and bronchioles till the alveoli.

Which of the following is the correct pathway of air while exhaling?

In order for the lungs to expel air the diaphragm relaxes, which pushes up on the lungs. The air then flows through the trachea then through the larynx and pharynx to the nasal cavity and oral cavity where it is expelled out of the body.

Why mean free path is important?

1.2. The mean free path is the average distance that a particle can travel between two successive collisions with other particles. From Formula 1-11 it can be seen that the mean free path displays linear proportionality to the temperature and inverse proportionality to the pressure and molecular diameter.

## What is meant by mean free path of a gas molecule on what factors does mean free path depends?

The factors on which the mean free path (λ) of a gas molecule depends are: (i) Diameter of the molecule: (ii) Number of gas molecules per unit volume: (iii) It depends indirectly on factors like temperature, pressure and Boltzmann constant.

### What is mean free path derive an expression for mean free path?

ˉλ=1πd2n. The expression for mean free path has been obtained by assuming that all the gas molecules except the one under consideration, are at rest. In fact, all the gas molecules are in random motion, their velocities being governed by Maxwell’s law of distribition of velocities.

How do you calculate the mean free path of a molecule?

Molecules of diameter x 10-10meters (angstroms) should have a mean free path of = x 10^m which is times the molecular diameter and times the average molecular separation of x 10^m. The values for pressure, temperature, and molecular diameter may be changed above to recalculate the mean free path.

How is the mean free path of particles in air derived?

There is a simple approximation for the mean free path, λ mfp, of particles in air at room temperature (T = 25 o C) given by, where λ mfp is in units of centimeters and the pressure, P, is in units of Torr. While this is a commonly used approximation, it is not clear how it is derived. The following is one way to arrive at this result.

## What is the free path of an atmospheric molecule?

Our estimate for σ used Ro = 3 Å. The mean free path of 1400 Å is more than 400 times as large, showing that an atmospheric molecule spends most of its time in free flight. In solids, insulators and semiconductors, as a result of ionization, electrons and holes are formed.

### How do you find the mean free path of a gas?

The mean free path of a single species of gas is given by, where n is the gas density and σ is the collisional cross section. While this expression for a single type of gas (i.e. not a mixture such as air), we will apply it for the derivation of our approximate solution.