Surface Tension using Quincke’s Method Aim, Apparatus, Procedure, Viva, Result, Observations & Calculations 2023

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Aim :

To determine the surface tension and the angle of contact of mercury with glass by Quincke’s method.

Apparatus :

Glass plate with three leveling screws, mercury, travelling microscope, spirit level, spherometer and lamp stand.

Surface Tension of mercury by QUINCKE’S METHOD - Experiment

 

Formula :

Surface Tension of mercury by QUINCKE’S METHOD - Experiment

 

Diagram :

Study Surface Tension of mercury by QUINCKE’S METHOD - Experiment

 

Procedure :

Amrita Virtual Lab Quincke’s Method Experiment – Click here 

Credit – SapnaShukla L&G

  1. Using a spirit level and the levelling screws make glass plate perfectly horizontal.
  2. Pour mercury on a horizontal clean glass plate to form a large drop with flat top.
  3. In order to take observations on the flat surface, base and maximum horizontal area use tip of spherometer. Fix the tip of the spherometer such that it just touches the flat surface of the drop.
  4. Illuminate the pin with light. Focus the horizontal cross wire of travelling microscope on the tip of the spherometer. Note down the reading(a) of the travelling microscope.
  5. Now take readings at maximum cross section (b) and at the base (c).
  6. Measure the height h of the drop and the distance h’ from its top to the horizontal plane of maximum cross section with the travelling microscope.
  7. Take observations for at least 6 drops of appreciable size.
  8. Determine the mean values of h and h’.

Observation :

 

Viva Question and Answers [FAQ] :

1. What do you mean by surface tension? 

Ans : Surface tension is the force acting per unit length perpendicular to the line drawn on the surface of the liquid.

2. Aim of experiment? 

Ans : To determine the surface tension and the angle of contact of mercury with glass by Quincke’s method.

3. What is unit of surface tension? 

Ans : SI unit – N/m 

          C.G.S. unit – dyne/cm 

4. What is the density of mercury? 

Ans : 1.36×10^4 kg/M3

5. Name of the apparatus used? 

Ans : Glass plate with three leveling screws, mercury, travelling microscope, spirit level, spherometer and lamp stand.

6. What is the angle of contact of Mercury? 

Ans : Ideal value of angle of contact is 135°.

7. What is responsible for surface tension? 

Ans : Cohesive forces among liquid molecules is responsible for surface tension.

8. Difference between Adhesive and Cohesive force. 

Ans : 
  • Adhesive force – It is the force between different substance.
  • Cohesive force – It is the force between same substance.

9. What is Angle of contact? 

Ans : Angle between solid surface and tangent to free surface of liquid.

10. Why is Mercury used in thermometer? 

Ans : 
  • Doesn’t sticks to glass
  • High boiling point
  • Hight coefficient of expansion.

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