Fick’s Law of Diffusion: Concentration, Formula & Application

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Fick’s law of diffusion is the law that explains the diffusion process in the derived form of equations. Diffusion is the spontaneous movement of atoms and molecules from their higher concentration to lower concentration in space. It is so named because it was described by Adolf Fick in 1855.

Table of Content

Fick’s Laws of Diffusion
Application of Fick’s law
Things to remember
Sample Questions

Key Terms: Diffusion, Fick’s Laws, Flux, Concentration of Matter

Also Read: Difference between Diffusion and Osmosis

Fick’s Laws Of Diffusion

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There are two of Fick’s laws of diffusion

First Fick’s law of diffusion: The molar flux due to diffusion is proportional to the concentration gradient.

The rate of change of concentration of any solution at a given point in space is directly proportional to the second derivative of concentration with space. It is given by the following equation:

N_i = -D_i ∇ c_i

Here for species i,

N_i is the molar flux (mol m^-2s^-1)

D_i is the diffusion coefficient (m²s^-1)

c_iis the concentration (mol m-³)

As per the continuity equation of mass:

∂c_i/ ∂t + ▽.N_i= 0

From the above equations, we can derive Fick's second law also

∂c_i/ ∂t = D_i▽²c_i

As per the equation, Di is a constant. It is valid for both concentrated and dilute solutions. It can be used to explain the diffusion of molecules in solids. liquids and gases.

Fick's law of diffusion

Fick's Law of Diffusion

Fick's Second Law of Diffusion: Fick’s second law of diffusion is a linear equation, where the variables are dependent. The variable is the concentration of the chemical substance. The diffusion of each chemical substance takes place independent of each other and that of temperature, pressure, etc.

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All about solutions

Types of solutions

Electrolytic cell

Application of Fick’s law

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Fick's law equations can be used to model transport processes in different categories like biopolymers, food items, pharmaceuticals, plasma physics, porous soils, population dynamics, nuclear materials, neutrons, and semiconductor doping processes. There are different fields where Fick’s law can be applied for practical purposes like biological application, liquids, fabrication of semiconductors, food industry, etc as follows:

Biological application: The exchange rate of gases through fluid membranes can be explained through Fick’s equation along with Graham’s law of diffusion.

Flux = −P(c₂−c₁) (Fick’s first law)

Here,

P is the permeability

c₂ - c₁ is the difference in concentration

Fick's law of diffusion

Fick’s Law of Diffusion

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Concentration cell

Neo-electrolytes

Colloids

Application in liquids: When two or more miscible liquids are combined diffusion takes place. The average or macroscopic concentration takes place as per Fick's law. On both mesoscopic scale and molecular-scale fluctuations in diffusion cannot be neglected. This kind of situation can be modelled with Landau-Lifshitz fluctuating hydrodynamics.

Application in the fabrication of semiconductors: Fick's law of diffusion can be used for the manufacture of integrated circuit fabrication technologies, model processes like Compact Video Disk, doping, thermal oxidation, and wet oxidation.

Application in pharmaceutical industries: It is used in medical science for research and development regarding healthcare.

Applications in food industries: Leaching and drying are controlled by internal diffusion.

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Principle of Homogeneity

Homogeneous Equilibrium

Things to Remember

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Fick’s law of diffusion is the law that explains the diffusion process is the derived form of equations.
Diffusion is the spontaneous movement of atoms and molecules from their higher concentration to lower concentration.
As per the first Fick’s law of diffusion, the molar flux due to diffusion is proportional to the concentration gradient.
Fick’s second law of diffusion is a linear equation, where the variables are dependent.
Fick's law equations can be used to model transport processes in different categories like biopolymers, food items, pharmaceuticals, plasma physics, porous soils, population dynamics, nuclear materials, neutrons, and semiconductor doping processes.
The exchange rate of gases through fluid membranes can be explained through Fick’s equation along with Graham’s law of diffusion.
The average or macroscopic concentration in liquids takes place as per Fick's law.
Fick's law of diffusion can be used for the manufacture of integrated circuit fabrication technologies, model processes like Compact Video Disk, etc

Kinetic theory

Science important questions

Sample Questions

Ques: What is Fick’s law for biological membranes? (2 marks)

Ans: Fick's law says that the rate of diffusion is proportional to the product of surface area and concentration difference in thickness of the membrane.

Ques: Why does the diffusion of A concerning B occur? (2 marks)

Ans: The concentration gradient of one substance is responsible for the diffusion of another substance as per Fick's law if there is passive diffusion down the concentration gradient.

Ques: What is Fick’s law? What are the factors that affect diffusion across membranes? (3 marks)

Ans: Fick's law says that the rate of diffusion is proportional to the product of surface area and concentration difference in thickness of the membrane.

Both surface area and thickness of the biological membranes affect diffusion. The surface area is proportional to the rate of diffusion. The thickness of the membrane and the distance travelled by a substance is inversely proportional to diffusion.

Ques: What is Fick’s law? How does concentration gradient affect diffusion across membranes in living cells as per Fick’s law? (3 marks)

Ans: Fick's law says that the rate of diffusion is proportional to the product of surface area and concentration difference in thickness of the membrane.

Molecules can move into or out of living cells by a process of diffusion. As the concentration of substances increases, there will be steeper the concentration gradient and faster the diffusion of molecules across the membrane. The direction of diffusion is said to be 'downhill' or as per the concentration gradient.

Ques: What is First Fick’s law of diffusion? What are the four variables in the numerator of Fick's Law of Diffusion? (3 marks)

Ans: As per the first Fick’s law of diffusion, the molar flux due to diffusion is proportional to the concentration gradient.

Fick's Law of diffusion states that the rate of diffusion of a gas across a semipermeable membrane will be determined by the chemical nature of the membrane, surface area of the membrane, partial pressure gradient of the gas, and thickness of the membrane.

Ques: What are the limitations of Fick's Law of diffusion? (2 marks)

Ans: Fick's first law is limited in radiation transfer equations. It is inaccurate while the diffusion constant is low. The radiation becomes limited due to the speed of light. It is not by the resistance of the material the radiation is flowing through it.

Ques: Why is diffusion important to living cells? (2 marks)

Ans: Diffusion allows cells to obtain the essential gases, liquids, and minerals for growth, development and cell division. It is also useful for the excretion of harmful waste products.

Ques: What are the different possible applications of Fick’s law? (5 marks)

Ans: Fick's law equations can be used to model transport processes in different categories like biopolymers, food items, pharmaceuticals, plasma physics, porous soils, population dynamics, nuclear materials, neutrons, and semiconductor doping processes.

Biological application: The exchange rate of gases through fluid membranes can be explained through Fick’s equation along with Graham’s law of diffusion.
Application in liquids: When two or more miscible liquids are combined diffusion takes place. The average or macroscopic concentration takes place as per Fick's law.
Application in the fabrication of semiconductors: Fick's law of diffusion can be used for the manufacture of integrated circuit fabrication technologies, model processes like Compact Video Disk, doping, thermal oxidation and wet oxidation.
Application in pharmaceutical industries: It is used in medical science for research and development regarding healthcare.
Applications in food industries: Leaching and drying are controlled by internal diffusion.

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Thermochemistry

Acid Test

Solvent

Fick’s Law of Diffusion: Concentration, Formula & Application

Fick’s Laws Of Diffusion

Application of Fick’s law

Things to Remember

Sample Questions

CBSE CLASS XII Related Questions

1.
Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

2.
Two thin lenses of focal length \( f_1 \) and \( f_2 \) are placed in contact with each other coaxially. Prove that the focal length \( f \) of the combination is given by \[ f = \frac{f_1 f_2}{f_1 + f_2}. \]

4.
Photoemission of electrons occurs from a metal (\( \phi_0 = 1.96 \, \text{eV} \)) when light of frequency \( 6.4 \times 10^{14} \, \text{Hz} \) is incident on it. Calculate: Energy of a photon in the incident light, The maximum kinetic energy of the emitted electrons, and The stopping potential.

5.
The figure shows three point charges kept at the vertices of triangle ABC. The net electric field, due to this system of charges, at the midpoint M of base BC will be:

6.
Write any two features of nuclear forces.

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Fick’s Law of Diffusion: Concentration, Formula & Application

Fick’s Laws Of Diffusion

Application of Fick’s law

Things to Remember

Sample Questions

CBSE CLASS XII Related Questions

1.Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

2.Two thin lenses of focal length \( f_1 \) and \( f_2 \) are placed in contact with each other coaxially. Prove that the focal length \( f \) of the combination is given by \[ f = \frac{f_1 f_2}{f_1 + f_2}. \]

4.Photoemission of electrons occurs from a metal (\( \phi_0 = 1.96 \, \text{eV} \)) when light of frequency \( 6.4 \times 10^{14} \, \text{Hz} \) is incident on it. Calculate: Energy of a photon in the incident light, The maximum kinetic energy of the emitted electrons, and The stopping potential.

5.The figure shows three point charges kept at the vertices of triangle ABC. The net electric field, due to this system of charges, at the midpoint M of base BC will be:

6. Write any two features of nuclear forces.

Comments

SUBSCRIBE TO OUR NEWS LETTER

1.
Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms per \( \text{m}^3 \). It is doped with \( 5 \times 10^{22} \) atoms per \( \text{m}^3 \) of Arsenic. Calculate majority and minority carrier concentration in the doped silicon. (Given: \( n_i = 1.5 \times 10^{16} \, \text{m}^{-3} \))

2.
Two thin lenses of focal length \( f_1 \) and \( f_2 \) are placed in contact with each other coaxially. Prove that the focal length \( f \) of the combination is given by \[ f = \frac{f_1 f_2}{f_1 + f_2}. \]

4.
Photoemission of electrons occurs from a metal (\( \phi_0 = 1.96 \, \text{eV} \)) when light of frequency \( 6.4 \times 10^{14} \, \text{Hz} \) is incident on it. Calculate: Energy of a photon in the incident light, The maximum kinetic energy of the emitted electrons, and The stopping potential.

5.
The figure shows three point charges kept at the vertices of triangle ABC. The net electric field, due to this system of charges, at the midpoint M of base BC will be:

6.
Write any two features of nuclear forces.