How does soap solidify into a solid?

According to historical records, the earliest soap formula originated in Mesopotamia in West Asia (meaning "the place between the two rivers", meaning between the Euphrates River and the Tigris River). About 3000 BC, people mixed 1 part oil and 5 parts alkaline plant ash to make a detergent. There are many legends about the origin of soap in Europe. Speaking of Gauls in ancient Rome, sheep oil and beech ash solution were stirred into a thick shape every holiday, applied to hair and combed into various hairstyles. Once a festival was caught in heavy rain, and the hairstyle was ruined, but people unexpectedly found that the hair became clean. It is also said that when the Romans sacrificed to the gods, the fat of roasted cattle and sheep dripped into the plant ash, forming a "grease ball". When women wash clothes, they find that clothes stained with "oil balls" are easier to clean. This shows that people have used animal fat and plant ash soap for thousands of years.

Archaeologists discovered a soap-making workshop in the ruins of Pompeii, Italy. This shows that the Romans had already started the primitive soap production as early as the 2nd century AD. China people have long known that plant ash and trona are used for washing clothes. People also mix pig pancreas and lard with natural pork to make a lump called "pancreas".

Early soap was a luxury. Until 179 1, French chemist Lublan successfully made caustic soda from electrolytic salt at a low price, thus ending the ancient method of making caustic soda from plant ash. 1823, German chemist Cheever discovered the structure and characteristics of fatty acids, and soap is one of them. /kloc-at the end of 0/9, the soap-making industry finally transformed from a manual workshop to industrial production?

Soap can decontaminate because it has a special molecular structure. One end of the molecule is hydrophilic and the other end is lipophilic. At the interface between water and oil, soap emulsifies oil and dissolves oil in soapy water. At the interface between water and air, soap surrounds air molecules to form soap bubbles. The dirt that was originally insoluble in water can no longer adhere to the surface of clothes because of the action of soap, but is dissolved in soap foam and finally washed away completely.

/kloc-in the 0/8th century, the French made "artificial soda" from salt and Carboniferous to replace the traditional alkali juice extracted from ashes. /kloc-in the 0/9th century, the Germans invented the electrolysis of brine to produce sodium hydroxide; Since then, the popularity of caustic soda has changed soap from a commodity that only the nobles in the palace can afford to a daily necessities for ordinary people.

Before that, the manufacture of soap depended on experienced craftsmen. It is prepared with oil-alkali ratio juice, because there is no information to refer to, and it is often tried again because it cannot be solidified.

It is worth mentioning that in the United States during the pioneer period, immigrants would choose warm days in early spring and gather the whole village to make soap.

The material source of soap is the astringent juice extracted from oak, beech and other wood as the source of alkali juice. If it is not enough, supplement it from the ashes of the heater. With alkaline juice, we can get oil from animal fat or vegetable oil for cooking, but once the oil and water are separated, we have to start all over again. Only in the19th century did enterprises invest in the production of soap.

Why is it called soap

Because the ancients used Gleditsia sinensis to wash clothes in the Yellow River valley, and there were no Gleditsia sinensis trees in the Yangtze River valley, they found a tree with the same performance as Gleditsia sinensis, which can also wash clothes, but it is more plump than Gleditsia sinensis, so they named her Gleditsia sinensis, also called Gleditsia sinensis fruit.

Later, when artificial detergents were invented, the word "soap" was still used.

Therefore, although there is no thin soap, there is a non-fat soap, namely "Gleditsia sinensis".

Soap (called Fan Jian in Guangdong) is a kind of surfactant used as personal cleaning products, which usually exists in solid blocks.

history

In ancient times, regardless of the east and west, the earliest washing ingredients were nothing more than sodium carbonate and potassium carbonate. The former is the product of natural lake minerals, and the latter is the main washing component of plant ash. The invention of soap is said to be Phoenician on the east coast of the Mediterranean. Legend has it that in a palace in ancient Egypt in the 7th century BC, a Phoenician chef accidentally knocked over a can of cooking oil. He was scared, so he quickly sprinkled the plant ash in the stove on it without anyone noticing, and then took it out and threw it away with his hand.

Looking at his greasy hands, he thought: I don't know when I can wash such dirty hands! He hesitated and put his hand in the water. Miracle happened: he just rubbed it a few times, and his greasy hands were easily washed off! Even the old dirt that was difficult to wash away was washed away. This cook was very strange, so he asked other chefs to taste this gray oil. As a result, everyone's hands are cleaner than before. Therefore, servants in the kitchen often wash their hands with oil and plant ash. Later, Lao Wang also knew the secret and asked the chef to make some plant ash oil to wash his hands.

Of course, legends are just legends after all, and they may not be completely taken seriously. But the Egyptian lake near Alexandria is rich in natural sodium carbonate, so the washing technology in ancient Egypt is relatively developed, and it is not surprising that soap was invented.

soap

It is the general name of fatty acid metal salts. The carbon number of fatty acids in daily soap is generally 10- 18. Metals are mainly alkali metals, such as sodium or potassium, but there are also ammonia and some organic bases, such as ethanolamine and triethanolamine, which are used to make soaps for special purposes. Soaps include laundry soap, soap, metal soap and liquid soap, as well as fatty acids, hardened oil and glycerol and other related products.

Soap contains not only higher fatty acid salts, but also fillers such as rosin, water glass, spices and dyes. Structurally, higher fatty acid sodium molecules contain nonpolar hydrophobic part (hydrocarbon group) and polar hydrophilic part (carboxyl group). Hydrophobic groups are lipophilic. When washing, the grease in the dirt is stirred and dispersed into fine oil droplets. After contacting with soap, hydrophobic groups (alkyl groups) of higher fatty acid sodium molecules are inserted into oil droplets and combined with oil molecules by van der Waals force. The hydrophilic group (carboxyl group) easily soluble in water partially extends out of the oil drop and is inserted into the water.

In this way, oil droplets are surrounded by soap molecules, dispersed and suspended in water to form emulsion, and then washed away by water through friction and vibration. This is the principle of soap decontamination. But ordinary soap should not be used in hard water or acidic water. Water-insoluble calcium stearate and magnesium stearate are formed in hard water, and water-insoluble fatty acids are formed in acidic water, which greatly reduces the decontamination ability.