To determine the surface tension of a give liquid using stalagmometer by drop countmethod.

 Experiment

 

(i) Drop count method

Aim:

To determine the surface tension of a give liquid using stalagmometer by drop countmethod.

Requirements:

• Stalagmometer

• Glycerin

• Water

• Specific gravity bottle

• Balance

Procedure:

• Select a clean and dry stalagmometerthan fix firmly in a vertical portion, in a beaker 

containing water and suck the water to the limb up to the level higher than the upper 

limb by using finger. 

• Leave the finger and allow the under water to flow down start counting of drops when 

the meniscus passes through the upper mark and until passes the lower mark ( the 

mumber of drops should be in between 15-20) repeat the experiment for 3 times. 

• Remove water and clean the stalagmometer.

• Select the liquid and repeat above step with liquid.

• Density of water and liquidare measure., them substitute these values together with 

number of drops of water and liquid in the equation and calculate the surface tension.

Calculation:

Weight of empty bottle (W1 ) = 

Weight of bottle with water (W2 ) = 

Weight of water (WW) = W1 – W2

LIQUID :

Weight of the empty bottle with liquid (W3) = 

Weight of liquid = W3 – W1 =

Density of water (g/v)= w1-w2

                                               V

Observation Table:

Surface tension of water √1 = 

Number of drops of water n1 =

Number of drops of liquid n2 = 

           γ2= n1ρ2

            γ1  n2ρ1

               𝛾2 = n1ρ2γ1

                             n2ρ1

Result:

Surface tension of the given liquid 𝛾2 =