Why do onions make us cry?

Do you all guys wonder why this thing does happen and how? I don really cook at home, but sometimes I do help my mom to cut some cooking stuff. Especially onion, which I don like to cut because it makes me cry... Does this thing happen to you all guys too...? I mean crying while cutting onions...

When you slice through an onion, you also cut through the onion cells. When the cells are cut, enzymes which are normally inside the cell are released. One of these enzymes, alliinase (from the onion), then reacts with a sulphur-containing compound known as ‘Prensco', that is also released by cutting the cells. This reaction results in the formation of 1-propenylsulphenic acid, which is further converted by the LF-synthase enzyme to propanethial S-oxide gas. This gas is also known as the Lachrymatory Factor (‘crying factor'), which also explains the name of the enzyme LF-synthase (meaning Lachrymatory Factor synthesising enzyme) 

This gas is instable and can react with water which results in, among others, sulphuric acid. When this happens in the eye, the eyes start to neutralise the acid by producing large amounts of water, and thus make us cry.

Many people start rubbing the eyes, which often works contra-productive if you just cut onions, as most likely your hands are covered with onion juice. Rubbing thus will make the irritation worse. 

How to chop onions without tears???

As a general rule, move your head as far away from the onion as you can, so the gas will mostly disperse before it reaches your eyes. 

Keeping the onion wet, or cutting under water is very effective, as the gas immediately reacts with the water around the onion and never reaches the eyes. 

Glasses and goggles also prevent the gas to penetrate the eyes to some degree, goggles being the most effective (although not practical). 

Cooling the onion may also help, as the enzyme activity is much slower at low temperatures. Cooking destroys the enzyme. 

Do you all know what is in coffee???

Coffee makes our morning fresh and energetic. The reason? Caffeine...

Caffeine is a central nervous system stimulant. It's one of the most popular drugs in the world, consumed by up to 90% of people in the world in one form or another, but mostly in beverages.

It is a naturally occurring substance found in plants like cocoa beans, tea leaves, and kola nuts.

Caffeine is a stimulant of the central nervous system (CNS), the cardiac muscle -increases heart rate, and respiratory system -relaxes air passages permitting improved breathing, and allows some muscles to contract more easily. It acts as a diuretic it increases the rate of bodily urine excretion, and delays fatigue -having the effect of warding off drowsiness and restoring alertness. Caffeine is probably the most popular drug in use because of these reasons. The effects that we might notice after consuming a large cup of coffee are hands getting cold, muscles tensing up, feeling of excitement and increased heart beat.

Effects of Caffeine

Caffeine absorption occurs in the body very quickly. It enters the bloodstream through the stomach and small intestine, and its effects are felt as soon as 15 minutes after consumption. It is completely absorbed within 45 minutes of ingestion. Caffeine does not accumulate in the bloodstream no is it stored in the body, but it does persist but only about ½ is eliminated in the urine within 6 hours. 

Caffeine sensitivity refers to the amount of caffeine that will produce negative side effects in a particular person. Regular caffeine consumption reduces sensitivity to caffeine, and a higher intake is needed for the same effects. So caffeine is considered to be an addictive drug. 

When we try to reduce caffeine intake, the body then becomes oversensitive to a chemical in the brain (adenosine) relevant to the sleep process, causing blood pressure to dropdramatically, producing an excess of blood in the head area (not necessarily on the brain), and leading to a headache often lasting several days. Other withdrawal symptoms reported are fatigue and muscle pain, irritability, inability to work, nervousness, restlessness, and feeling sleepy, and in extreme cases, nausea and vomiting. 

Cigarettes

Smokes don’t think about the chemical in the cigarettes. They only think about how cigarettes help them cope with the stress of daily life, how cigarettes calm them down when they we're angry, help them relax at the end of a long day, comfort them when they were sad or lonely. But do they know that there are harmful chemical in cigarettes???

When the chemicals in cigarettes are inhaled, they put our bodies into a state of physical stress by sending literally thousands of poisons, toxic metals and carcinogens coursing through our bloodstream with every puff we take. And those chemicals affect everything from blood pressure and pulse rate to the health of our organs and immune system. Most of the lung cancer related deaths are due to smoking. We do know that air tainted with cigarette smoke is dangerous for anyone who breathes it whether they are smoker or not.

Let's we look at some of the harmful chemicals in cigarettes and how does they affect our health.

The main ingredient in a cigarette is tobacco. Tobacco is a harmful substance. Chemicals and preservatives are added to the tobacco and filled into the cigarette. According to a recent study there are more than 3000 chemicals in the cigarette smoke. Worldwide smoking by teens has increased rapidly.

Carcinogens

A carcinogen is defined as any substance that can cause or aggravate cancer. Approximately 60 of the chemicals in cigarettes are known to cause cancer.

TSNAs

Tobacco-specific N-nitrosamines (TSNAs) are known to be some of the most potent carcinogens present in smokeless tobacco, snuff and tobacco smoke.

Benzene

Benzene can be found in pesticides and gasoline. It is present in high levels in cigarette smoke and accounts for half of all human exposure to this hazardous chemical.

Pesticides

Pesticides are used on our lawns and gardens, and inhaled into our lungs via cigarette smoke.

Formaldehyde

Formaldehyde is a chemical used to preserve dead bodies, and is responsible for some of the nose, throat and eye irritation smokers experience when breathing in cigarette smoke.

Toxic Metals

Toxic / heavy metals are metals and metal compounds that have the potential to harm our health when absorbed or inhaled. In very small amounts, some of these metals support life, but when taken in large amounts, can become toxic.

Arsenic

Commonly used in rat poison, arsenic finds its way into cigarette smoke through some of the pesticides that are used in tobacco farming.

Cadmium
Cadmium is a toxic heavy metal that is used in batteries. Smokers typically have twice as much cadmium in their bodies as non-smokers.

Poisons

Poison is defined as any substance that, when introduced to a living organism, causes severe physical distress or death. Science has discovered approximately 200 poisonous gases in cigarette smoke.


Ammonia

Ammonia compounds are commonly used in cleaning products and fertilizers. Ammonia is also used to boost the impact of nicotine in manufactured cigarettes.

Carbon Monoxide

Carbon monoxide is present in car exhaust and is lethal in very large amounts. Cigarette smoke can contain high levels of carbon monoxide.

Hydrogen Cyanide
Hydrogen cyanide was used to kill people in the gas chambers in Nazi Germany during World War II. It can be found in cigarette smoke.

Nicotine

Nicotine is a poison used in pesticides and is the addictive element in cigarettes.


This is only a partial list. Recent breaks in the wall of secrecy have revealed that cigarettes are only about 40% tobacco, and 60% other junk. So smokes please stop smoking, because it is very bad for health.

People are dying every year because of cigarettes...

How does soap and detergents work???

We use soap and detergents frequently in our daily life. We use them to wash our hands & body and to clean our clothes without knowing how this thing does really work...

Soaps and detergents are very similar in their chemical properties. However, there is a significant difference between them, which soaps are produced from natural products, and detergents are synthetic, or man-made.

Detergents and soaps are used for cleaning because pure water can't remove oily, organic soiling. Soap cleans by acting as an emulsifier. Basically, soap allows oil and water to mix so that oily grime can be removed during rinsing. Detergents were developed in response to the shortage of the animal and vegetable fats used to make soap during World War I and World War II. Detergents are primarily surfactants, which could be produced easily from petrochemicals. Surfactants lower the surface tension of water, essentially making it 'wetter' so that it is less likely to stick to itself and more likely to interact with oil and grease. 

Modern detergents contain more than surfactants. Cleaning products may also contain enzymes to degrade protein-based stains, bleaches to de-colour stains and add power to cleaning agents, and blue dyes to counter yellowing. Like soaps, detergents have hydrophobic or water-hating molecular chains and hydrophilic or water-loving components. The hydrophobic hydrocarbons are repelled by water, but are attracted to oil and grease. The hydrophilic end of the same molecule means that one end of the molecule will be attracted to water, while the other side is binding to oil. Neither detergents nor soap accomplish anything except binding to the soil until some mechanical energy or agitation is added into the equation. Swishing the soapy water around allows the soap or detergent to pull the grime away from clothes or dishes and into the larger pool of rinse water. Rinsing washes the detergent and soil away. Warm or hot water melts fats and oils so that it is easier for the soap or detergent to dissolve the soil and pull it away into the rinse water. Detergents are similar to soap, but they are less likely to form films (soap scum) and are not as affected by the presence of minerals in water (hard water). 

Modern detergents may be made from petrochemicals or from oleochemicals derived from plants and animals. Alkalis and oxidizing agents are also chemicals found in the detergents. 

Petrochemicals/Oleochemicals

These fats and oils are hydrocarbon chains which are attracted to the oily and greasy grime.

Oxidizers

Sulfur trioxide, ethylene oxide, and sulfuric acid are among the molecules used to produce the hydrophilic component of surfactants. Oxidizers provide an energy source for chemical reactions. These highly reactive compounds also act as bleaches.

Alkalis

Sodium and potassium hydroxide are used in detergents even as they are used in soap making. They provide positively charged ions to promote chemical reactions.

Types of detergent 

Synthetic detergents have similar molecular structures and properties as soap. Although the cleansing action is similar, the detergents do not react as readily with hard water ions of calcium and magnesium. Detergent molecular structures consist of a long hydrocarbon chain and a water soluble ionic group. Most detergents have a negative ionic group and are called anionic detergents. The majority are alky sulfates. Others are "surfactants" (from surface active agents) which are generally known as alkyl benzene sulfonates.

Anionic Detergents

Cationic Detergents

Another class of detergents have a positive ionic charge and are called "cationic" detergents. In addition to being good cleansing agents, they also possess germicidal properties which make them useful in hospitals. Most of these detergents are derivatives of ammonia.

A cationic detergent is most likely to be found in a shampoo or clothes "rinse". The purpose is to neutralize the static electrical charges from residual anionic (negative ions) detergent molecules. Since the negative charges repel each other, the positive cationic detergent neutralizes this charge.
It even works because the ammonium (+1) nitrogen is buried under the methyl groups as can be seen in the space filling model.

Neutral or non-ionic detergents

Nonionic detergents are used in dish washing liquids. Since the detergent does not have any ionic groups, it does not react with hard water ions. In addition, nonionic detergents foam less than ionic detergents. The detergent molecules must have some polar parts to provide the necessary water solubility.

On the above graphic, the polar part of the molecule consists of three alcohol groups and an ester group. The non-polar part is the usual long hydrocarbon chain.

Bile Salts - Intestinal Natural Detergents

Bile acids are produced in the liver and secreted in the intestine via the gall bladder. Bile acids are oxidation products of cholesterol. First the cholesterol is converted to the trihydroxy derivative containing three alcohol groups. The end of the alkane chain at C # 17 is converted into an acid, and finally the amino acid, glycine is bonded through an amide bond. The acid group on the glycine is converted to a salt. The bile salt is called sodiumglycoholate. Another salt can be made with a chemical called taurine.

The main function of bile salts is to act as a soap or detergent in the digestive processes. The major action of a bile salt is to emulsify fats and oils into smaller droplets. The various enzymes can then break down the fats and oils.

Soap

Soaps are sodium or potassium fatty acids salts, produced from the hydrolysis of fats in a chemical reaction called saponification. Each soap molecule has a long hydrocarbon chain, sometimes called its 'tail', with a carboxylate 'head'. In water, the sodium or potassium ions float free, leaving a negatively-charged head. 

Soap is an excellent cleanser because of its ability to act as an emulsifying agent. An emulsifier is capable of dispersing one liquid into another immiscible liquid. This means that while oil (which attracts dirt) doesn't naturally mix with water, soap can suspend oil/dirt in such a way that it can be removed.

The organic part of a natural soap is a negatively-charged, polar molecule. Its hydrophilic (water-loving) carboxylate group (-CO2) interacts with water molecules via ion-dipole interactions and hydrogen bonding. The hydrophobic (water-fearing) part of a soap molecule, its long, nonpolar hydrocarbon chain, does not interact with water molecules. The hydrocarbon chains are attracted to each other by dispersion forces and cluster together, forming structures called micelles. In these micelles, the carboxylate groups form a negatively-charged spherical surface, with the hydrocarbon chains inside the sphere. Because they are negatively charged, soap micelles repel each other and remain dispersed in water.



Grease and oil are nonpolar and insoluble in water. When soap and soiling oils are mixed, the nonpolar hydrocarbon portion of the micelles break up the nonpolar oil molecules. A different type of micelle then forms, with nonpolar soiling molecules in the center. Thus, grease and oil and the 'dirt' attached to them are caught inside the micelle and can be rinsed away. 

Although soaps are excellent cleansers, they do have disadvantages. As salts of weak acids, they are converted by mineral acids into free fatty acids:

CH3(CH2)16CO2-Na+ + HCl ----> CH3(CH2)16CO2H + Na+ + Cl-

These fatty acids are less soluble than the sodium or potassium salts and form a precipitate or soap scum. Because of this, soaps are ineffective in acidic water. Also, soaps form insoluble salts in hard water, such as water containing magnesium, calcium, or iron. 

2 CH3(CH2)16CO2-Na+ + Mg2+ ----> [CH3(CH2)16CO2-]2Mg2+ + 2 Na+

The insoluble salts form bathtub rings, leave films that reduce hair luster, and gray/roughen textiles after repeated washings. Synthetic detergents, however, may be soluble in both acidic and alkaline solutions and don't form insoluble precipitate in hard water.