How Does Soap How Does Soap Work?Work?

History of SoapHistory of Soap

Soap was one of the first Soap was one of the first chemical compounds chemical compounds ever made by man.ever made by man.

The first soaps were The first soaps were probably the saps of probably the saps of certain plants, such as certain plants, such as the Soap Plant the Soap Plant ((Chlorogalum Chlorogalum pomeridianumpomeridianum), whose ), whose roots can be crushed in roots can be crushed in water to form a lather, water to form a lather, and used as a shampoo.and used as a shampoo.

When was soap first When was soap first used?used?

Some hypothesize that even Some hypothesize that even prehistoric man had a primitive form of prehistoric man had a primitive form of soap. soap. 

Soaps have been excavated in clay Soaps have been excavated in clay cylinders that date back to 2800 cylinders that date back to 2800 B.C. By 1500 B.C. B.C. By 1500 B.C.

Egyptians medical scrolls recommend Egyptians medical scrolls recommend a soap made from alkaline salts anda soap made from alkaline salts and

animal and vegetable oils animal and vegetable oils

for skin conditions. for skin conditions.

What is saponifcation?What is saponifcation?

Later, people learned that fats would react Later, people learned that fats would react with alkalies in the ashes left over from a fire with alkalies in the ashes left over from a fire to produce saponified compounds to produce saponified compounds

SaponificationSaponification is commonly used to refer to is commonly used to refer to the reaction of a metallic alkali (base) with a the reaction of a metallic alkali (base) with a fat or oil to form soap. fat or oil to form soap.

+ =

How is soap made How is soap made today?today?

Today, soaps are made Today, soaps are made from fats and oils that from fats and oils that react with lye (react with lye (sodium sodium hydroxidehydroxide). ).

Solid fats like coconut oil, Solid fats like coconut oil, palm oil, tallow (rendered palm oil, tallow (rendered beef fat), or lard (rendered beef fat), or lard (rendered pork fat), are used to form pork fat), are used to form bars of soap that stay hard bars of soap that stay hard and resist dissolving in the and resist dissolving in the water left in the soap dish. water left in the soap dish.

The Structure of SoapThe Structure of Soap

How does soap clean How does soap clean your clothes?your clothes?

Because of that dualism, soap molecules act like Because of that dualism, soap molecules act like a diplomat, improving the relationship between a diplomat, improving the relationship between water and oil.water and oil.

How? When soap is added to the water, the How? When soap is added to the water, the hydrophilic hydrophilic (polar)(polar) heads of its molecules stay heads of its molecules stay into the water (they like it!), while the long into the water (they like it!), while the long hydrophobichydrophobic (nonpolar)(nonpolar) chains join the oil chains join the oil particles and remain inwards (escaping from the particles and remain inwards (escaping from the water). water).

What is a Micelle?What is a Micelle?

In that way, they form circular groups named In that way, they form circular groups named micellesmicelles, with the , with the oily material absorbed inside and trapped.oily material absorbed inside and trapped.

A micelle is a spherical body, which arises when amphiphilic molecules aggregate.  These present their hydrophilic 'head' groups to the aqueous solvent and their hydrophobic 'tails' are buried within the micelle.

What other What other ingredients go into ingredients go into soap making?soap making? Glycerin:Glycerin: Emollient and texture Emollient and texture

enhancerenhancer BHT:BHT: anti oxidant to preserve the oils anti oxidant to preserve the oils

from going rancidfrom going rancid Sorbitol:Sorbitol: Helps make glycerine soaps Helps make glycerine soaps

more transparentmore transparent Titanium Dioxide:Titanium Dioxide: Makes soap opaque Makes soap opaque PEG-6 methyl ether:PEG-6 methyl ether: Surfactant, Surfactant,

detergent, emulsifier to make dyes detergent, emulsifier to make dyes and perfumes blend evenly and perfumes blend evenly