Hard soaps (Latin : sapo medicatus), also termed soda soaps in older terminology, are categorized under soaps and are typically sodium salts of fatty acids. They vary in color from white to brownish and have a fatty acid content ranging from 72 to 75%. These soaps are typically made from lower-quality fats. Hard soaps serve as the foundation for products frequently labeled as fine soaps, which are fortified with nourishing additives, perfumes, and dyes.
The term hard soap originates from the soap production process. During this process, the addition of salt (sodium chloride) to boiling soap mixed with a substantial amount of water causes the soap nucleus to separate and solidify, making it "harder" and allowing it to float on the surface.
Through the process of saponification, fats (like tallow, pig, and bone fats) or vegetable oils react with sodium hydroxide to form the sodium salts of fatty acids and glycerin. [1] The resulting mixture is known as soft soap [ broken anchor ], which serves as a precursor for hard soap production. After adding sodium chloride (a process known as salting out), the soap nucleus rises and separates. The water-soluble glycerin and unwanted fat residues remain in the solution (see also soap [ broken anchor ]).
The fatty acid salts formed during production constitute the actual soap and are effective cleaners due to their surfactant properties. Using soap helps dissolve many water-insoluble substances, like fats and oils, making them washable with water.
In most cases, hard soaps or products based on them are used for handwashing because they exhibit an alkaline (pH value above 7) nature and can irritate the skin when in contact with mucous membranes. Hard soap has antiseptic qualities and can be used alongside warm water as a household remedy for paronychia. It's also used to shape dreadlocks.
In the realm of detergents, soaps are generally secondary due to the creation of soap scum. They are primarily utilized as defoamers.
Beyond cleaning, soaps also treat wood surfaces. They enhance the appearance of conifer woods, seal the wood's pores, minimize dirt accumulation, and prevent staining from fats or embedded dyes. [2] For cleaning brushes, especially in oil painting, hard soap ensures extended durability of the bristles or hairs.
On occasion, water-based soap solutions are employed for pest control on cultivated plants, like against thrips and aphids.
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group attached to an R-group. The general formula of a carboxylic acid is often written as R−COOH or R−CO2H, sometimes as R−C(O)OH with R referring to an organyl group, or hydrogen, or other groups. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion.
Soap is a salt of a fatty acid used for cleaning and lubricating products as well as other applications. In a domestic setting, soaps, specifically "toilet soaps", are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are used as thickeners, components of some lubricants, emulsifiers, and catalysts.
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations Na+ and hydroxide anions OH−.
Sodium chloride, commonly known as edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chlorine ions. It is transparent or translucent, brittle, hygroscopic, and occurs as the mineral halite. In its edible form, it is commonly used as a condiment and food preservative. Large quantities of sodium chloride are used in many industrial processes, and it is a major source of sodium and chlorine compounds used as feedstocks for further chemical syntheses. Another major application of sodium chloride is deicing of roadways in sub-freezing weather.
Sodium carbonate is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water. Historically, it was extracted from the ashes of plants grown in sodium-rich soils, and because the ashes of these sodium-rich plants were noticeably different from ashes of wood, sodium carbonate became known as "soda ash". It is produced in large quantities from sodium chloride and limestone by the Solvay process, as well as by carbonating sodium hydroxide which is made using the chloralkali process.
Saponification is a process of cleaving esters into carboxylate salts and alcohols by the action of aqueous alkali. Typically aqueous sodium hydroxide solutions are used. It is an important type of alkaline hydrolysis. When the carboxylate is long chain, its salt is called a soap. The saponification of ethyl acetate gives sodium acetate and ethanol:
Stearin, or tristearin, or glyceryl tristearate is an odourless, white powder. It is a triglyceride derived from three units of stearic acid. Most triglycerides are derived from at least two and more commonly three different fatty acids. Like other triglycerides, stearin can crystallise in three polymorphs. For stearin, these melt at 54 (α-form), 65, and 72.5 °C (β-form).
In chemistry, the common-ion effect refers to the decrease in solubility of an ionic precipitate by the addition to the solution of a soluble compound with an ion in common with the precipitate. This behaviour is a consequence of Le Chatelier's principle for the equilibrium reaction of the ionic association/dissociation. The effect is commonly seen as an effect on the solubility of salts and other weak electrolytes. Adding an additional amount of one of the ions of the salt generally leads to increased precipitation of the salt, which reduces the concentration of both ions of the salt until the solubility equilibrium is reached. The effect is based on the fact that both the original salt and the other added chemical have one ion in common with each other.
Stearic acid is a saturated fatty acid with an 18-carbon chain. The IUPAC name is octadecanoic acid. It is a soft waxy solid with the formula CH3(CH2)16CO2H. The triglyceride derived from three molecules of stearic acid is called stearin. Stearic acid is a prevalent fatty-acid in nature, found in many animal and vegetable fats, but is usually higher in animal fat than vegetable fat. It has a melting point of 69.4 °C (156.9 °F) °C and a pKa of 4.50.
Biodiesel production is the process of producing the biofuel, biodiesel, through the chemical reactions of transesterification and esterification. This process renders a product (chemistry) and by-products.
Laundry detergent is a type of detergent used for cleaning dirty laundry (clothes). Laundry detergent is manufactured in powder and liquid form.
Bath salts are water-soluble, pulverized minerals that are added to water to be used for bathing. It is said that these salts improve cleaning, enhance the enjoyment of bathing, and serve as a vehicle for cosmetic agents. Bath salts have been developed which mimic the properties of natural mineral baths or hot springs. Some bath salts contain glycerine so the product will act as an emollient, humectant, or lubricant. Fragrances and colors are often added to bath salts; the fragrances are used to increase the users' enjoyment of the bathing experience.
Oleochemistry is the study of vegetable oils and animal oils and fats, and oleochemicals derived from these fats and oils. The resulting product can be called oleochemicals (from Latin: oleum "olive oil"). The major product of this industry is soap, approximately 8.9×106 tons of which were produced in 1990. Other major oleochemicals include fatty acids, fatty acid methyl esters, fatty alcohols and fatty amines. Glycerol is a side product of all of these processes. Intermediate chemical substances produced from these basic oleochemical substances include alcohol ethoxylates, alcohol sulfates, alcohol ether sulfates, quaternary ammonium salts, monoacylglycerols (MAG), diacylglycerols (DAG), structured triacylglycerols (TAG), sugar esters, and other oleochemical products.
Cleaning agents or hard-surface cleaners are substances used to remove dirt, including dust, stains, foul odors, and clutter on surfaces. Purposes of cleaning agents include health, beauty, removing offensive odors, and avoiding the spread of dirt and contaminants to oneself and others. Some cleaning agents can kill bacteria and clean at the same time. Others, called degreasers, contain organic solvents to help dissolve oils and fats.
A metallic soap is a metallic salt of a fatty acid. Theoretically, soaps can be made of any metal, although not all enjoy practical uses. Varying the metal can strongly affect the properties of the compound, particularly its solubility.
Wet Processing Engineering is one of the major streams in Textile Engineering or Textile manufacturing which refers to the engineering of textile chemical processes and associated applied science. The other three streams in textile engineering are yarn engineering, fabric engineering, and apparel engineering. The processes of this stream are involved or carried out in an aqueous stage. Hence, it is called a wet process which usually covers pre-treatment, dyeing, printing, and finishing.
Saltwater soap, also called sailors' soap, is a potassium-based soap for use with seawater. Inexpensive common commercial soap will not lather or dissolve in seawater due to high levels of sodium chloride in the water. Similarly, common soap does not work as well as potassium-based soap in hard water where calcium replaces the sodium, making residual insoluble "scum" due to the insolubility of the soap residue. To be an effective cleaning agent, soap must be able to dissolve in water.
Taurates (or taurides) are a group of mild anionic surfactants. They are composed of a hydrophilic head group, consisting of N-methyltaurine (2-methylaminoethanesulfonic acid) and a lipophilic residue, consisting of a long-chain carboxylic acid (fatty acid), both linked via an amide bond. The fatty acids used could be lauric (C12), myristic (C14), palmitic (C16) or stearic acid (C18), but mainly mixtures of oleic acid (C18:1) and coconut fatty acid (C8 – C18) are used. Besides sodium, no other counterions play a relevant role (these could be e. g. ammonium or other alkali or alkaline earth metals).
