SOAPS

Soaps are water-soluble sodium or potassium salts of fatty acids. Soaps are made from fats and oils, or their fatty acids, by treating them chemically with a strong alkali.

First, i will explain the composition of fats, oils and alkalis, then the soapmaking process.

Fats and Oils

The fats and oil used in soapmaking come from animal or plant sources. Each fat or oil is made up a distinctive mixture of several different triglycerides.

In a triglyceride molecule, three fatty acid molecules are attached to one molecule of glycerine. There are many types of triglyceride; each types consists of its own particular combination of fatty acids.

Fatty acids are the components of fats and oils that used in making soap. They are weak acids composed of two parts;

A carboxylic acid group consisting of one hydrogen atom, two oxygen atoms, and one carbon atom, plus a hydrocarbon chain attached to the carboxylic acid group. Generally, its made up a long straight chain of carbon atom each carrying two hydrogen atoms.



Alkali

An alkali is a soluble salt of an alkali metal like sodium or potassium. Originally, the alkalis used in soapmaking were obtained from the ashes of plant, but they are now made commercially. Today, the term alkali describe a substance that chemically is a base(the opposite of an acid) and that reacts with and neutralizes an acid.

The common alkalis used in soapmaking are sodium hydroxide(NaOH), also called caustic soda; and potassium hydroxide(KOH), also called caustic potash.

How Soaps are Made

Saponification of fats and oils is the most widely used soapmaking process. This method involves heating fats and oils and reacting them with a liqiud alkali to produce soap and water (neat soap) plus glycerine.

The other major soapmaking process is the neutralization of fatty acids with an alkali. Fats and oils are hydrolyzed (split) with a high-pressure steam to yield crude fatty acids and glycerine. The fatty acids are then purified by distillation and neutralized with an alkali to produce soap and water (neat soap).

When the alkali is sodium hydroxide, a sodium soap is formed. Sodium soaps are "hard" soaps. When the alkali is potassium hydroxide, a potassium soap is formed. Potassium soaps are softer and foun in some liqiud hand soap and shaving creams.

The carboxylate end of the soap molecule is attached to water. It is called the hydrophilic (water-loving) end. The hydrocarbon chain is attracted to oil and grease and repelled by water. It is known as the hydrophilic (water-hating) end.

How Water Hardness Affects Cleaning Action
Although soap is a good cleaning agent, its effectiveness is reduced when used in hard water. Hardness in water is caused by the presence of mineral salts - mostly those of calcium (Ca) and Magnesium (Mg), but sometimes also iron (Fe) and manganese (Mn). The mineral salts react eith soap to form an insoluble precipitate known as soap film or scum.

Soap film does not rinse away easily. It tends to remain behindand produces visible deposits on clothing and makes fabrics feels stiff. It also attaches to the insides of bathtubs, sinks and washing machines.

Some soap is used up reacting with hard water to form the film. This reduces the amount of soap available for cleaning. Even when clothes are washed in soft water, some hardness minerals are introduced by the soil on clothes. Soap molecules are not very versatile and cannot adapted to today's varietyof fibres, washing temperatures and water condition.

HAIR DYE

The first safe commercial haircolor was created in 1909 by French chemist Eugene Schuller, using the chemical paraphenylenediamine. Hair coloring is very popular today, with over 75% of women coloring their hair and a growing percentage of men following suit. How does haircolor work? It's the result of a series of chemical reactions between the molecules in hair, pigments, as well as peroxide and ammonia, if present.

What is Hair?

Hair is mainly keratin, the same protein found in skin and fingernails. The natural color of hair depends on the ratio and quantities of two other proteins, eumelanin and phaeomelanin. Eumelanin is responsible for brown to black hair shades while phaeomelanin is responsible for golden blond, ginger, and red colors. The absence of either type of melanin produces white or gray hair.

Natural Colorants

People have been coloring their hair for thousands of years using plants and minerals. Some of these natural agents contain pigments (e.g., henna, black walnut shells) and others contain natural bleaching agents or cause reactions that change the color of hair (e.g., vinegar). Natural pigments generally work by coating the hair shaft with color. Some natural colorants last through several shampoos, but they aren't necessarily safer or more gentle than modern formulations. It's difficult to get consistent results using natural colorants, plus some people are allergic to the ingredients.

Temporary Hair Color

Temporary or semi-permanent haircolors may deposit acidic dyes onto the outside of the hair shaft or may consist of small pigment molecules that can slip inside the hair shaft, using a small amount of peroxide or none at all. In some cases, a collection of several colorant molecules enter the hair to form a larger complex inside the hair shaft. Shampooing will eventually dislodge temporary hair color. These products don't contain ammonia, meaning the hair shaft isn't opened up during processing and the hair's natural color is retained once the product washes out.

How Lightening Works

Bleach is used to lighten hair. The bleach reacts with the melanin in hair, removing the color in an irreversible chemical reaction. The bleach oxidizes the melanin molecule. The melanin is still present, but the oxidized molecule is colorless. However, bleached hair tends to have a pale yellow tint. The yellow color is the natural color of keratin, the structural protein in hair. Also, bleach reacts more readily with the dark eumelanin pigment than with the phaeomelanin, so some gold or red residual color may remain after lightening. Hydrogen peroxide is one of the most common lightening agents. The peroxide is used in an alkaline solution, which opens the hair shaft to allow the peroxide to react with the melanin.

Permanent Hair Color

The outer layer of the hair shaft, its cuticle, must be opened before permanent color can be deposited into the hair. Once the cuticle is open, the dye reacts with the inner portion of the hair, the cortex, to deposit or remove the color. Most permanent hair colors use a two-step process (usually occurring simultaneously) which first removes the original color of the hair and then deposits a new color. It's essentially the same process as lightening, except a colorant is then bonded within the hair shaft. Ammonia is the alkaline chemical that opens the cuticle and allows the hair color to penetrate the cortex of the hair. It also acts as a catalyst when the permanent hair color comes together with the peroxide. Peroxide is used as the developer or oxidizing agent. The developer removes pre-existing color. Peroxide breaks chemical bonds in hair, releasing sulfur, which accounts for the characteristic odor of haircolor. As the melanin is decolorized, a new permanent color is bonded to the hair cortex. Various types of alcohols and conditioners may also be present in hair color. The conditioners close the cuticle after coloring to seal in and protect the new color.

ACID RAIN

Many people are worried about acid rain. now let me explain briefly about what acid rain is, its main components, its effects, and what we can do about them.

What is acid rain?
“Acid rain” is “substances acidified by pollutants in the air precipitating from the sky” Actually there are two kinds of acid rain, wet deposition and dry deposition

Wet Deposition
Wet deposition means acidic rain, mist, snow and so on. Acidic water sprinkles down from the sky and sinks into the soil. During this process, it exerts many influences on animals and plants.

Dry Deposition
Dry deposition means acidic air or particles. Approximately half of the acidic substances in the air return to the ground as dry deposition. Acidic particles adsorbed on walls of buildings or on trees form acidic water when they are rinsed away by rain. Acidic particles can travel over more than several hundred kilometers in the wind.

Main sources of acid rain
It is thought that sulfur dioxide (SO₂) and nitrogen oxides (NOx) are the main agents causing acid rain. Acidic substances (sulfuric acid, nitric acid) are generated when these substances react with water, oxygen, etc in the air. This reaction is promoted by sunlight.

Sulfur dioxide and nitrogen oxides are mainly generated when fossil fuels, such as petroleum, coal, or natural gas, are burned. Thus, they are generated from human activity, such as automobiles, factories, and power plants.

Effects of acid rain
Acidification and damage to lake
The number of fish in an acidified lake decreases drastically at below pH 5, because plankton and water plants, which are pH sensitive, are affected. At below pH 4, eggs are not hatched and the gills of adult fish are harmed. It is reported that around 4000 lakes in Ontario in Canada, near the US border, are acidified, and around 1300 lakes in Quebec, next to Ontario, are affected also.

Damage to Forest
Acid rain directly destroys the wax layer or cuticle (which protects the surface of leaves), harms stoma, and inhibits photosynthesis and respiration. Acid rain indirectly causes an alteration of the soil. Clay in soil has a property of ion exchange. Under acidic conditions, H⁺ is adsorbed on the surface of clay and Ca²⁺ etc. are eluted instead. Al³⁺ is also eluted at a lower pH. Trees lack nutrition if Ca²⁺ and Mg²⁺ are washed away. In addition, Al³⁺ is toxic. At above 0.1 ppm of Al³⁺, the ends of the roots are damaged, and cell division and growth there is prevented.

What we can do?
What we can do individually is so small that it appears meaningless; however, remember that acid rain is the accumulation of what every single person generates in his/her daily life. Therefore, it is very important that each of us try to do something.

First of all, let’s begin to understand the issue of acid rain and the solutions to this problem.

Energy consumption is closely related to the issue of acid rain. Thus, reducing personal energy consumption is one of the best ways in which an individual can act.

For example, how about trying to do the following things?

• Turn off the power to electric appliances when they are not in use.

• Use public transportation, bicycle, or your feet as much as possible.
  

• Purchase a low-pollution car and use it for a long time.

GLUE

WHY DOES A GLUE STICK HAVE ADHESIVE FORCE, EVEN THOUGH IT IS NOT STICKY?

First of all, I will explain the reason why adhesives, such as glue, are able to attach things together.

When an adhesive is pasted on the surface of a material (adherend), the adhesive penetrates into the small gaps on the adherend surface, and then hardens and does not move any more inside the gap. It is thought that this inability to move is one of the reasons that things attach together. This effect is called the “anchor effect“, because like a ship with a dropped anchor the adhesive does not move. There are chemical bonds between adhesive molecules and adherend molecules, which also make them stick together. These bonds are, for example, hydrogen bond, Van der Waals bond, ionic bond, and covalent bond.

On the other hand, since the attraction force is generated when
one molecule comes close to another molecule, it is necessary that the adhesive is brought near to the solid surface by liqiud. Because the penetration of the adhesive into the adherend surface is important for adhesion, and the strength of adhesion depends on several effects above, we cannot always say, "to feel sticky=to have adhesive force".

The reason why glue stick does not feel very sticky when we touch it would be that PVP is solidified. Fatty acid(sodium salt) is added for solidifying the glue stick, and glycols are added for smoothing. So the solid form of a glue stick does not feel very sticky to touch, but when we use the solid form breaks up and stickiness increases.

BAKING SODA

Since early times, baking soda has been used as baking powder, abrasive, deodorant, cleaner and so on. Does anyone ever wonder why baking soda has so many functions?

Chemical properties of baking soda
Baking soda (sodium hydrogen carbonate or sodium bicarbonate, NaHCO₃), which is the weakest alkali among sodium compounds, has the following effects because of its properties:

Deodorizing
The mechanism of deodorizing by baking soda is neutralization of acids and bases. So NaHCO₃ can remove the acid odour only. It works efficiently in fridges, garbage disposals and footwear cupboards etc.

Baking

Carbon dioxide (CO₂) gas, generated when baking soda is broken down by heat (1), makes dough rise. You may notice that when you make pancakes because bubbles are formed as they cook.

2NaHCO₃ ↔ Na₂CO₃ + CO₂+ H₂O (1)

Polishing

The hardness of the particle is about 2.5 on the new Mohs hardness scale, so it can remove dirt without damaging materials such as stainless steel and iron which have high values of new Mohs hardness. However, it may damage soft metals such as aluminium and copper since their values of Mohs hardness are relatively low. So please be careful when you rinse such metals with baking soda.

Washing

Concerning the removal of dirt sticking on the surface of pots, put water in the pot, boil it and leave it overnight. The chemical reaction above occurs at high temperature so that the pH of the solution in the pot is increased (pH of baking soda is around 8, pH of Na₂CO₃ is around 11). The fat in the dirt is partially saponified and the fiber in the dirt is also softened by alkali so that water can go into the gap between the stuck on dirt and surface. Then the dirt is easily removed.

Cooking beans

Baking soda is also used to soften beans quickly. Proteins in beans are dissolved and the fibers in the beans are also softened by alkali so that water can go inside the beans more easily.

Caring for silver

Dullness of silver (Ag), commonly called tarnish, can be removed completely using baking soda. The tarnish is silver sulfide (Ag₂S), formed when the surface of silver reacts with hydrogen sulfide (H₂S) which exists in the air in small amounts. In order to remove the tarnish, first of all, aluminium (Al) foil is put on the bottom of a pot, and baking soda and almost boiling water are put in the pot. Then tarnished silverware is placed on the aluminum foil. The difference of redox potentials between Ag and Al is so large that they form a kind of battery. Added baking soda serves as an electrolyte in this system. Therefore, the electrons move from Al to Ag so that Ag₂S releases S and the surface becomes Ag again. This process causes the tarnished silverware to become shiny again.

Baking soda is a weak base and so it is not a powerful detergent like strong alkali which breaks down fat. However, it can remove dirt with the properties mentioned above.

In order to prevent alkali from damaging our skin, always remember to use rubber gloves when using baking soda.