how does soap work on the molecular level?

Question

how does it get all the dirt off my hands?

Answer 1

Soap is amphoteric. True soap is a sodium or potassium salt of long chain fatty acids. As such it has a polar head, so it can dissolve in water, and hydrophobic tails, which dissolve grease and grime. The soap works with water to mobilize the gunk with the soap micelles (groups of soap molecules), allowing the water to carry away the dirt.

Answer 2

The soap () dissolves by the principle of 'like dissolves like'. Soap contains inorganic cations, like Na or K and organic anions like the ester, palmitate, stearate, etc. It is this organic anion that has an interesting property. On one end it has long chain of hydrophobic( water hating) or conversely grime, dirt loving fatty acid backbone. On the other end, is the carboxylate hydrophilic (water loving) portion of the long fatty acid ester. The hydrophobic portion will dissolve like molecules of non-polar in nature while the hydrophillic portion will dissolve charged or ionic inorganic and small charged organic dirts.

Thus, the cleansing property of the soap is based on this fact that it is able to both dissolve organic and inorganic dirts.

Then, once dissolved, the soap form micelles that carry off the dirts down the drain. Think of micelles as traps or flexible containers.

Now, by you rubbing your hands, it makes it easier for the soap to get in contact with the underlying dirt and thus when you open the tap with flowing water, there goes the dirt and soap.

Answer 3

Soap is basically a water soluable oil. Dirt is usually a combination of solid contaminants mixed with body oil. The soap oil does not separate the contaminants from your body. Actually it combines with the body oil since they are mutually attracted and combined at the molecular level and it traps the contaminants with it. When they are rinsed with water, water soluable soap oil dissolves taking with it the dirty oil.

Answer 4

Something in soap lubricates water and makes it super soft. The softer the water, the more dirt and debris it will remove.