How does a soap bubble develop?
When air is blown into the soap skin,
the elastic mixture of soap and water
envelops the air and forms a soap bubble.
Dr Bubbles explains
The molecules of the soap, called surfactants, push themselves to the interface between air and water. These surfactants reduce the surface tension of the water and make the surface of this mixture elastic and expandable. Now you can blow air into the soap-water mixture without immediately ripping the surface. This is how the fascinating soap bubbles are created. At the same time, the soap molecules prevent the soap bubble from dying too quickly due to dehydration.
In water, the soap molecules decompose into electrically positive and electrically negative particles. The positive particles are distributed inside the soap bubble skin while the negative particles sit in a thin layer on the surface of our soap bubble skin. The negative particles on the surface consist of a hydrophilic end that loves the water and a hydrophobic part that loves the compound with fat. The water-loving hydrophilic part protrudes into the water, while the fat-loving hydrophobic end looks into the air. This creates a protective layer of soap molecules that slows down the evaporation of water and prolongs the life of our bubbles.
Why can't you blow bubbles with water alone?
If you try to make a bubble only with water, you will not succeed. The small water bubbles that form immediately shrivel or burst. This is due to the fact that the water molecules press very closely together. The attraction between the water molecules, called surface tension, is too strong. Therefore the water skin tears immediately when you try to inflate it.
Dr Bubbles thanks Professor Dr Haag for his scientific support.