When fingers dipped in soapy water are placed in, why does pepper move to one side?

 

The ultra-popular surface tension experiment during the COVID-19 pandemic!!

 

 

If fingers previously dipped in a cleansing agent are immersed in water, why does pepper move to one side? Does the same phenomenon occur?

 

The answer is... yes!

 

Initially, due to surface tension, pepper grains float evenly distributed.

 

When fingers (previously immersed in a degreasing agent) are dipped into the water, soap particles are squeezed between the water particles, reducing surface tension. The oil layer moves to one side and drags the pepper flakes along.

 

Why use degreasers to clean surfaces?

 

Viral envelopes (the outer structure of some viruses) are composed of fat (lipids) and embedded virus proteins. This example demonstrates that lipid-dissolving cleansers can disrupt the lipid membrane, thereby preventing viral transmission. Cleaning surfaces with powerful degreasers can be effective.

 

Let's explain each step of this experiment!

 

Step 1: Prepare the cleaning agent to be tested (water-based)

 

 

Step 2: Fill a cup nine-tenths full with water

 

 

Step 3: Add salad oil to the cup, nearly filling it

 

 

Step 4: Sprinkle an appropriate amount of pepper

 

 

Step 5: Insert fingers into the water and observe the reaction (without touching the cleansing agent)

 

 

Step 6: Wet fingers with an appropriate amount of cleansing agent

 

 

Step 7: Insert fingers into the water and observe the change in pepper in the water

 

 

(Source: https://www.youtube.com/watch?v=PQe7yOfV_oI)