# What is meant by equimolar counter diffusion?

Table of Contents

## What is meant by equimolar counter diffusion?

Equimolar counterdiffusion is an instance of molecular diffusion in a binary mixture, and occurs when equal numbers of molecules of the two substances are moving in opposite directions.

## What is mass transfer by diffusion?

Diffusion is a mass transfer phenomenon that causes the distribution of a chemical species to become more uniform in space as time passes. In this case, species is a chemical dissolved in a solvent or a component in a gas mixture, such as the oxygen in air.

## Is mass transfer same as diffusion?

Mass transfer is the movement of mass from one place to another. Diffusion is a form of mass transfer. The main difference between mass transfer and diffusion is that mass transfer may or may not occur across a concentration gradient whereas diffusion occurs across a concentration gradient.

## What is pseudo steady state diffusion?

Pseudo-steady state (PSS) flow occurs during the late time region when the outer boundaries of the reservoir are all no flow boundaries. During the PSS flow regime, the reservoir behaves as a tank. The pressure throughout the reservoir decreases at the same, constant rate.

## How does mass transfer occur in equimolar counterdiffusion?

In this process, the net molar flow rate of the mixture and the molar-average velocity are equal to zero, and mass transfer occurs by diffusion only without any convection taking place. The mole fraction, the molar concentration, and the partial pressure of both gases involved in equimolar counterdiffusion vary linearly.

## Which is the molar flux of mass transfer?

The molar flux of A is NA,z= − AcDAB dy dz + yA(NA,z+ NB,z) = − cDABA dy dz For steady state and constant area of mass transfer NA,z= constant. Separating the variable and integrating

## How are mole fraction and partial pressure related in equimolar counterdiffusion?

The mole fraction, the molar concentration, and the partial pressure of both gases involved in equimolar counterdiffusion vary linearly. These relationships can be found in the following equations expressing the molar flow rates for each species, A and B, for a one-dimensional flow through a channel with no homogenous chemical reactions:

## How is K G related to mass transfer?

The diffusion in the bulk fluide compensate the utilisation of B at the surface of the catalyst. k g is the mass transfer coefficient. Although the mixture is stationary due to the molar flow rate and velocity being zero, the net mass flow rate of the mixture is not equal to zero unless the molar mass of A is equal to the molar mass of B.