Determination of surface tension by drop count method

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BACKGROUND

The stalagmometer consist of a glass capillary tube with a bulb at the middle.There is a capillary bore at the tip of the stalagmometer. The surface tension of the liquid can be calculated using following formula.1-3

Where,   v1 =surface tension of test liquid

v2 =surface tension of water

ρ12 =Density of test liquid &water

n1=no.of drops of test liquid

n2=no .of drops of water

Aim: To determine the surface tension of given liquid by drop count method using stalagmometer.

REQUIREMENTS


Apparatus:     Stalagmometer,

Beakers,

Measuring cylinder.

Chemicals:     Water,

Acetone,

Ethanol,

Benzene.

PROCEDURE

The liquid which is to e tested was sucked into the clean stalagmometer upto mark A. Then it was allowed to fall down due to gravity. The no. Of drops were calculated when the liquid passes from mark A to B.

The procedure was repeated 3 times to obtain the mean value.Then the surface tension can be calculated using above formula.


Tabulation

LIQUID

NO OF DROPS

DENSITY

SURFACE TENSION

1

2

3

MEAN

WATER

ETHANOL

ACETONE

TOLUENE

CONCLUSION

From the above expt. We concluded that the surface tension of the given liquid is found to be————-.

REFERENCES

  1. More HN, Hajare AA. Practical Physical Pharmacy. Career Publications. 2010:104-105.
  2. Gaud RS, Gupta GD. Practical Physical Pharmacy. CBS Publisher and Distributors. 2009: 62-63.
  3. Mohanta GP. Physical Pharmacy Practical Text, Pharma Book Syndicate. 2006: 31-32.