# Measurement of Surface & Interfacial Tension Important Questions Physical Pharmacy

Important Questions on Measurement of Surface & Interfacial Tension Physical Pharmacy

Important Questions:

1. Explain DuNouy Ring Method for determination of surface tension and interfacial tension. Give equation involved in this method.
2. Explain Drop Weight and Drop Count Method for determination of surface tension.
3. Explain Wilhelmy Plate Method for determination of Surface & Interfacial Tension.
4. Explain Spinning Drop method for determination for Interfacial Tension.
5. Explain Maximum bubble pressure method for determination of surface tension.

Surface Tension Methods: a. Capillary Rise Method
b. Drop Formation Method
1. Drop Weight method
2. Drop Number Method
c. Ring Detachment Method
d. Maximum Bubble Pressure Method
e. Wilhelmy Plate Method.
Interfacial Tension Method:1. Spinning Drop Method – Ring is immersed in liquid
2. Du Noxy Tensiometer Method / Ring Detachment Method
3. Wilhelmy Plate Method – Plate is immersed in liquid.

Important Question with Solutions:

Contents

### 1. Explain DuNouy Ring Method for determination of surface tension and interfacial tension. Give equation involved in this method.

DuNouy tensiometer is widely used to measure surface and interfacial tensions. The instrument is shown in Figure. This method is convenient for rapid determination, especially when the quantity of liquid available is small.
The principle is illustrated with the help of a Figure. The force required to detach the platinum-iridium ring immersed at the interface or surface is measured. The force is equal to surface or interfacial tension.
The derivation for the determination of interfacial tension (surface tension) by DuNouy ring method is as follow.

### 5. Explain Maximum bubble pressure method for determination of surface tension.

Important formula:

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