Chemical reaction is not a mechanism of mass transfer. It involves the transformation of one substance into another, while mass transfer refers to the movement of mass from one location to another.

The rate of diffusion is directly proportional to the concentration gradient, which is the difference in concentration between two regions.

Flow of air through a pipe is an example of convective mass transfer, where the mass is transported by the bulk motion of the fluid.

Distillation is a separation process that utilizes the differences in volatility of the components in a mixture to separate them.

In a packed bed reactor, the mass transfer between the fluid and the solid particles is primarily governed by diffusion, as the fluid flows through the packed bed and comes into contact with the solid particles.

The mass transfer coefficient, $k_c$, is a measure of the rate of mass transfer, which is the amount of mass transferred per unit time and area.

The rate of mass transfer is affected by temperature, pressure, concentration, and surface area.

Distillation is a separation process that utilizes the differences in boiling points of the components in a mixture to separate them.

The rate of mass transfer in a gas-liquid mass transfer operation is influenced by gas flow rate, liquid flow rate, temperature, and surface area.

Filtration is a separation process that involves the physical separation of solids from fluids, and is not a type of mass transfer operation.

The mass transfer coefficient, $k_c$, is affected by fluid properties, system geometry, and operating conditions.

Evaporation of milk, drying of fruits, and pasteurization of milk are all examples of mass transfer operations in the food industry.

The mass transfer between the fluid and the solid particles in a packed bed reactor is influenced by particle size, particle shape, and packing density.

Filter press is a separation equipment used for solid-liquid separation, and is not a type of mass transfer equipment.

The mass transfer coefficient, $k_c$, is a function of diffusion coefficient, viscosity, and density.