Electrical Double Layer and its Uses batry

electrical double layer ppt

1. ELECTRICAL DOUBLE LAYER

2. CONTENTS :- INTRODUCTION ELECTRICAL DOUBLE LAYER(EDL) LAYERS OF EDL CONCEPTS BASED ON EDL APPLICATIONS REFERENCES

3. INTRODUCTION :- Helmholtz (1879) explained qualitatively the electrical properties of colloids on the concept of electrical double layer at solid-liquid interface. All the molecules or particles carry out a electric charge due the their properties. Study of reaction in which charged particles cross the interface between two phases of matter, such as interface between a solid and a liquid. Electrochemistry and the surface and colloidal chemistry can be combine with this phenomena.

4. ELECTRICAL DOUBLE LAYER THEORY When electrode immersed in an electrolytic solution, charge accumulation will occur. Particle size should be greater than 1 nm. Charge separation always occur at the interface of the electrodes in the solution. The excess charge on the electrode surface is accumulated by an accumulation of the excess ions of the opposite charge in the solution.

5. EDL is a transition region between two phases consists of, 1. An inner molecular layer 2. An outer diffuse region 3. A layer intermediate between inner molecular layer and the outer diffuse layer

6. LAYERS OF EDL According to Stern, an electrical double layer consists of two parts; ( 1 ) One part of the double layer , known as fixed part ( STERN LAYER ) remains almost fixed to the solid surface. It has positive or negative ions. There is a sharp fall of potential. ( 2 ) The second part of the double layer, known as diffuse part ( DIFFUSE LAYER ) extends to some distance into the liquid phase. This layer contains ions of both signs. Its net charge is equal and opposite to that on the fixed part. There is gradual fall of potential into the bulk of the liquid where the charge distribution is not uniform.

7. STERN LAYER Also known as the Stationary Layer Occurs in next to the surface of the particle. Ions are bound to the surface very firmly. Occurs due to the absorbing and coulomb interaction.

8. DIFFUSE LAYER Occurs next to the Stern layer. This layer is called as bulk liquid layer. Occurs in between the stern layer and the bulk. Both positive and negative charges can be seen.