Celebrating chemistry

Jagadish G Baragi tells us how chemistry is intrinsically linked to our lives

Chemistry is a big part of our everyday life. Everything is made of chemicals. You are made of chemicals. So is your dog. So is your desk. So is the sun. Drugs are chemicals. Food is made from chemicals. Many of the changes you observe in the world around you are caused by chemical reactions. Examples include changing colours of leaves, cooking food and getting clean. Knowing some chemistry can help you make day to day decisions that affect your life. Indeed all living processes are controlled by chemical reactions.

The International Union of Pure and Applied Chemistry (IUPAC) and UNESCO strongly believe that it is time to celebrate the achievements of chemistry and its contributions to the well-being of humankind and UN General Assembly declared year 2011 as the International Year of Chemistry.

The aim of celebrating the International Year of Chemistry is to:

* Increase the public appreciation of chemistry in meeting world needs
* Increase interest of young people in chemistry
*Generate enthusiasm for the creative future of chemistry
*Celebrate the 100th anniversary of the Mme. Curie’s Nobel Prize and the 100th anniversary of the founding of the International Association of Chemical Societies.

The emotions that you feel are a result of chemical messengers, primarily neurotransmitters. Love, jealousy, envy, infatuation and infidelity all share a basis in chemistry.

Nonverbal communication plays a big part in initial attraction which is due to pheromones, a form of chemical communication. Do you know that raw lust is characterised by high levels of testosterone? The 'high' of being in love is due to a rush of phenylethylamine and dopamine. Lasting love confers chemical benefits in the form of stabilised production of serotonin and oxytocin. Can infidelity be blamed on chemistry? Perhaps in part. Researchers have found that suppression of vasopressin can cause males to abandon their love nest and seek new mates.

What is it in onions that makes them burn your eyes? When you cut an onion, you break cells, releasing their contents. Amino acid sulfoxides form sulfenic acids. Enzymes that were kept separate now are free to mix with the sulfenic acids to produce propanethiol S-oxide, a volatile sulfur compound that wafts upward toward your eyes. This gas reacts with the water in your tears to form sulfuric acid. The sulfuric acid burns, stimulating your eyes to release more tears to wash the irritant away.

Cooking the onion inactivates the enzyme, so while the smell of cooked onions may be strong, it doesn't burn your eyes.

Soap is a chemical that mankind has been making for a very long time. How can something so nasty actually make you cleaner? The answer has to do with the way soap interacts with oil-based grease and grime. Soaps are sodium or potassium fatty acids salts, produced from the hydrolysis of fats in a chemical reaction called saponification.
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 interacts with water molecules forming structures called micelles. 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 centre. Thus, grease and oil and the ‘dirt’ attached to them are caught inside the micelle and can be rinsed away.

Food goes bad because of chemical reactions that occur between food molecules. Fats can become rancid. Bacteria grow that can make you sick.

 Can bottled water go bad? Most bottled water has an expiration date stamped on the bottle, but does the bottled water actually go bad? If so, how long is bottled water good? Here’s the answer to this common question.

Some bottled water only carries its bottling date or a ‘best by’ date. These dates are helpful because the flavour of the water will change over time as it absorbs chemicals from its packaging. The flavour will not necessarily be bad, but it may be noticeable.

Leaching of chemicals from packaging is a health concern, but as far as toxic chemicals go, you can get exposure to most of those chemicals from freshly bottled water as well as bottled water that has been on the shelf a while. A ‘plastic’ taste is not necessarily an indicator that the water is bad; absence of an unpleasant flavour does not mean the water is free from contaminants.

While algae and bacteria will not grow in sealed bottled water, the situation changes once the seal has been broken. You should consume or discard water within 2 weeks after opening it.

You can apply chemistry to decide when and where to use household chemicals. While you might think detergent is detergent, so it’s interchangeable from one application to another, there are some good reasons why laundry detergent should stay in the washing machine and not in the dish washer.  The detergent itself may be the same from one product to the other, but laundry detergents may contain brighteners, fragrances, stain removers, and anti-soiling chemicals that you don't really need volatilised by the heat of your dishwasher so that you breathe them. The ingredients in laundry detergent might not rinse completely from your dishes.

Sunscreen uses chemistry to filter or block the sun’s harmful ultraviolet rays to protect you from sunburn, skin cancer, or both. Sunscreen combines organic and inorganic chemicals to filter the light from the sun so that less of it reaches the deeper layers of your skin.

Like a screen door, some light penetrates, but not as much as if the door wasn't present. Sunblock, on the other hand, reflects or scatters the light away so that it doesn't reach the skin at all.  The reflective particles in sunblocks usually consist of zinc oxide or titanium oxide. In the past, you could tell who was using a sunblock just by looking, because the sunblock whited out the skin.

Many common household chemicals are dangerous. They may be reasonably safe when used as directed, yet contain toxic chemicals or degrade over time into a more dangerous chemical. Here’s a list of some of the most dangerous household chemicals, including the ingredients to watch for and the nature of the risk.

Thus Chemistry, appropriately called the Central Science, is both a deeply philosophical inquiry and an applied scientific endeavour. The science of chemistry is fundamental to humanity’s understanding of the world and the cosmos. Molecular transformations are central to the production of foodstuffs, medicines, fuels, metals, i.e., virtually all manufactured and extracted products.

Through IYC the chemical community will publicly celebrate the art and science of chemistry, its key contributions to developing human knowledge, advancing economic progress and fostering a wholesome environment.