In this experiment, we will determine the increase in surface tension of water after increasing the amount of detergent in it.
To determine the effect of increasing the amount of detergent on surface tension.
1. If the surface tension of water gets affected by the addition of detergent in it, the capillary tube will rise with increasing concentration. It would rise up to the point where the addition of excess detergents will not affect the surface tension anymore.
2. We hypothesized that the height of the water in the capillary tube after adding detergent in it would decrease.
2. Capillary tube
3. Detergents or soap
Step 1: Take distilled water in a capillary tube.
Step 2: Add detergent or soap into the same tube.
Step 3: Record the height of the capillary tube after the addition of detergent or soap.
Step 4: Continue adding the detergent until the capillary height does not get constant.
Step 5: Record your observations.
Surface Tension of Water in Capillary Tube
1. From the experiment, we observed that without detergent, the water acquired a height of 16mm into the capillary tube. But after adding detergent, the height decreased to 6mm.
2. The height of the capillary tube had not decreased more than 6mm.
1. The hypothesis in which we assumed that the height of the soap solution in the capillary tube would decrease was correct.
2. We also hypothesized that the surface tension of soap in water (soap solution) would approximately be one-third of distilled water was correct
3. The capillary height of the soap solution was 37.5 percent of the distilled water’s capillary height.
1. Record your observation precisely.
2. Continuously add the soap to the water.
In this experiment, we determined the effect of increasing the amount of detergent or soap on the surface tension of distilled water.
Viva Questions With Answers
Q.1 What was the aim of your experiment?
ANS. We aimed to determine the effect of detergent on surface tension.
Q.2 What was the effect of soap solution on capillary tube height?
ANS. The height of the capillary tube decreased with the increasing amount of soap in the water.
Q.3 What is the relation between the surface tension of soap solution and distilled water?
ANS. The surface tension of the soap solution is one-third of distilled water.
Saquib Siddiqui is a Mechanical Engineer and a content creator. He has special interest in science experiments and teaches the same to school and college students. He is also a technical lead at RUDE LABS PVT. LTD.