Archives for category: chemistry

I hate cutting onions. Actually, I used to hate cutting onions. Now I am not bothered by the tears. Onions were just too good to give up over a few tears.

When we cut open an onion, we allow an enzyme called alliinases to react and break down amino acid to generate sulphenic acid. At this point the chemical still remains on the cutting board– so how does it get to our eyes?


A second enzyme called lachrymatory factor synthase or LFS later mix with sulphenic acidto form, get ready for this, propanethiol S-oxidePropanethiol S-oxide is a volatile gas, and it travels readily in the air. When the gas reaches your eyes, it mixes with water in your eyes to form sulfuric acid. This prompts our eyes to release water to irrigate the irritating invader.

The natural reaction to the Propanethiol S-oxide invasion is to shut your eyes. This, of course, is not a good idea if you are cutting an onion. Rubbing your eyes is a bad idea, since your hands are likely full of the tear-making onion juice, and by rubbing your eyes you are actually transferring the sulphenic acid to your eyes, in addition to the sulfuric acid induced by the Propanethiol S-oxide gas.


So how do you keep from crying? I believe there are many methods out there, or some traditional methods passed down from mom to child. One that I have tried and works is from WikiHow.  It suggests briefly freezing the onion, using a sharp knife, and cutting near a strong fume hood. Downside- I never prepare far enough in advance and freeze the onion.

Another tried and true, if not inconvenient method is to cut underwater.  I believe the water dilutes the chemicals making it a cry free experience. But then who has the time, space and inclination to cut onions underwater every time?

Otherwise, I’ll stick to wearing goggles. This works like a charm, is quick and ideal for the lazy chef.




The Pufferfish is considered the second deadliest vertebrate in the world, after the Golden Poison Frog. The common image we have of this creature is that it inflates when threatened. I have kept these fish in an aquarium, and in my experience they rarely puff out in captivity.

What makes the Pufferfish, also called the Fugu so popular is the lethal toxin in its liver, skin and the ovaries, and the fact that the Japanese treat it as a delicacy. Pretty ironic I guess? By the way it is extremely expensive and prepared only by trained, licensed chefs who, like all humans, occasionally make mistakes.


Almost all pufferfish contain tetrodotoxin, a substance that makes them foul tasting and often lethal to fish. To humans, tetrodotoxin is deadly, up to 1,200 times more poisonous than cyanide. The toxin paralyzes the muscles, including the muscles in our diaphragm, which is essential for breathing. The victim eventually dies of asphyxiation. There is enough toxin in one pufferfish to kill 30 adult humans, and there is no known antidote. Tetrodotoxin has been isolated from widely differing animal species, including western newts of the genus Taricha (where it was formerly termed “tarichatoxin”), pufferfishtoads of the genus Atelopus, several species of blue-ringed octopuses of the genusHapalochlaena (where it was called “maculotoxin”), several sea stars, certain angelfish, a polyclad flatworm, several species of Chaetognatha (arrow worms), several nemerteans (ribbonworms) and several species of xanthid crabs.

Tetrodotoxin molecule


Negative aspects aside, Puffer Fish makes cute companion.

Of course, don’t go around scaring puffer fish because a puffer fish could only perform a limited number of inflation in its life.


When a Pufferfish is threatened, it will pump itself up by taking 35 gulps or so in the course of 14 seconds. Each gulp draws in a big load of water thanks to some peculiar anatomic changes in the muscles and bones. The entire fish balloons as it continuously takes water into its stomach.

The stomach expands to nearly a hundred times its original volume, and the fish’s spine, already slightly curved, bends into an upside-down U shape, and all other internal organs become squeezed between the fish’s backbone and its rapidly expanding stomach. Meanwhile, the fish’s skin is pushed out, obscuring most of the puffer’s features-

Image: Sally J. Bensusen. American Museum of Natural History.

Sometimes they have difficulties expelling water from their stomach, and hence they actually risk dying every time they inflate. I guess we should record a default video showing one individual inflating itself on a public website to prevent curious divers/swimmers/fishers going around harming more Pufferfish. Pufferfish belong to family Tetraodontidae is a family of primarily marine and estuarine fish of the order Tetraodontiformes. The family includes many familiar species, which are variously called pufferfishpuffersballoonfishblowfishbubblefishglobefishswellfishtoadfishtoadies,honey toadssugar toads, and sea squab. They are morphologically similar to the closely related porcupinefish, which have large external spines (unlike the thinner, hidden spines of Tetraodontidae, which are only visible when the fish has puffed up). The scientific name refers to the four large teeth, fused into an upper and lower plate, which are used for crushing the shells of crustaceans and mollusks, their natural prey.

With all of this, many people still consider Fugo to be a delicacy , especially in Japan.


I stumbled upon a number of interesting papers recently, which are in fact genuine scientific investigations into matters we often take for granted, for example –  the radiation level of bananas.


I’ve read about radioactive bananas(oh by the way, all bananas are radioactive) in my nuclear physics class, and yet I never got bothered by it.
Bananas are radioactive because they contain potassium-40, which is pretty unstable. But you don’t have to worry about gulping down the yellowish-radioactive-fruit, because it takes a whopping 37,290,000,000 bananas to kill you, and still, it won’t qualify you for the Xavier Institute for Higher Learning.


The paper takes 450mg as the mean amount of potassium contained in a banana. Of this, only a small percentage of the total mass is represented by potassium-40, around 0.0117%(5.27mg). The half-life of this small fraction is around 1.26 billion years, making the decay relatively slow, and hence ensuring a continuous burst of energy throughout your life. A banana equivalent dose (abbreviated BED) is a nonstandard unit of radiation exposure, ostensibly defined as the additional dose a person will absorb from eating one banana.

The concept is based on the fact that bananas, like most organic material, naturally contain a certain amount of radioactive isotopes—even in the absence of any contamination due to human nuclear endeavors. The banana equivalent dose was meant to express the severity of exposure to radiation, such as resulting from nuclear powernuclear weapons or medical procedures, in terms that would make sense to most people.

The amount of energy released, however, is minute, around 0.0000000000000931 J/s, roughly 0.000000000107 Gray. It takes around 1 Gray to cause radiation sickness in an adult, and it takes 4 times that to have a good chance of killing someone. The simple multiplication that ensues gives 37,290,000,000 bananas.

Assuming that a dude takes a banana a day, oh… he would have to pump his age up to 102 million years in order to acquire enough bananas to kill himself.

No, no. They don’t form anything like the Hulk, and definitely won’t form a super-molecule containing one of everything.

There are two methods of putting it to the test, neither of which are practical.

The first method would require energy equivalent to dozens of Large Hadron Colliders-an impressive and extremely treacherous experiment indeed. The second method would be putting together a chunk of each element and observe what happens.

Both, however, would eventually create carbon monoxide and a pile of rust and salts rather than a cool Frankenstein element.


Atoms are made up of a nucleus of neutrons and protons with a set number of electrons circling around them. Molecules form when atoms’ electron orbitals overlap and effectively hold the atoms together. What you get when you mix all your atoms will be influenced by what’s close to what.
Oxygen, for example, is very reactive, and if it is closest to hydrogen, it will make hydroxide. If it is nearest to carbon, it will make carbon monoxide. Certain elements, such as the noble gases, wouldn’t react with anything.
Bombarding the atoms together at 99.999 % the speed of light in the Large Hadron Collider might be able to break protons, but it could also be used to fuse a few nuclei together. But still it won’t produce anything supernatural-and if there’s any, it would probably decay into something more common in a fraction of a second. Moreover, you would need 118 colliders-one to accelerate each element in the Periodic Table to get the task done, which sounds pretty quixotic to me.


Another approach would be to toss a pulverized chunk of each element or a puff of each gas into a sealed container and observe the consequence. No one has ever tried this experiment either, but here’s how scientists think things would play out: The oxygen gas would react with alkaline metal (lithium or sodium) and ignite, raising the temperature in the container to the point that even Devil himself would complain. There are roughly 25 radioactive elements, and they would make your flaming stew a little dangerous. Flaming plutonium is a very bad thing-inhaling airborne radioactive material can cause rapid death.
Once temperature drops, the result would be as boring as the atoms-only scenario. Carbon and oxygen would yield carbon monoxide and carbon dioxide. Nitrogen gas is very stable, and would remain as is. The noble gases wouldn’t react, nor would a few of the metals, like gold and platinum, which are mostly found in their pure forms. The things that do react will form rust and salts. 

Some smaller level reactions can be shown here with cool videos. Take water and sodium. Two things we have at home, maybe even on the dinner table. Sodium in its elemental form is highly reactive to water.

Check out this video: Sodium v Water (slow motion) – Periodic Table of Videos

 Zinc and sulfer another another fantastic combo.   Zinc and Sulfur – Periodic Table of Videos 
Of course not just sodium reacts with water.  So does potassium.