Tag: chemistry

Posted in Science & Nature

Badass Weapons Of Nature: Bombardier Beetle

Posted on by Jinavie

The bombardier beetle, or Brachymus creptians, has a “machine gun”. When attacked, it makes an explosive sound and spouts smoke.
This beetle combines chemicals from two separate glands to make the smoke. 
The first gland produces a solution of 25% hydrogen peroxide and 10% hydroquinone, while the second gland produces peroxidase, an enzyme that catalyses the reaction. When these solutions are combined and heated to 100°C, smoke and nitric acid vapour is produced and explosively released.

If you put your hand close to a bombardier beetle, it will rapidly release a scalding, noxious, red vapour. This nitric acid will cause blisters on afflicted skin.
Bombardier beetles also know how to aim the tip of its abdomen to target an enemy. Via this method, it can hit a target a few centimetres away. Even if it misses, the explosive sound will scare away any predator. 
Normally, bombardier beetles store enough chemicals for three or four shots. However, some entomologists have found that some species can fire up to 24 times in rapid succession if provoked.

As these beetles are a bright orange and silver-blue colour, they are very noticeable. They act as if they do not care if they are seen, as they are equipped with an effective cannon. Generally, beetles with a colourful coat have a unique, ingenious defensive mechanism to ward off curious animals and insects.
Despite this, rats that know that the beetle loves to use this “ingenious defensive mechanism” quickly grab the beetle and plant its abdomen in the ground. After attacking it continuously while in the ground to exhaust the beetle’s rounds, the rat bites off the head first.

(from the Encyclopaedia of Relative and Absolute Knowledge by Bernard Werber)

Posted in Science & Nature

Piquance

Posted on by Jinavie

When the word taste is mentioned, people often think of sweet, sour, bitter, salty, savoury and spicy. But among these, only the first five are officially “tastes”. Spiciness is technically not a taste; it is rather a type of pain.
Due to the confusion between the words hot (which could mean temperature) and spicy (suggesting there are spice, but not specifying what type), scientists devised a new word called piquance to correctly name the sensation.
Piquance is caused by chemicals such as capsaicin stimulating the densely packed nerve fibres in mucous membranes in the mouth, causing pain. This sensation can be sensed anywhere covered by thin skin or membrane such as the eye. Tear gas and pepper spray exploit this by attacking the eyes, disabling sight, and the respiratory system, crippling breathing by inducing cough reflexes, to nullify the target.

Being a sensation, piquance can be seen as a subjective measure. Is there an objective way of measuring the piquance of a food?
In 1912, an American pharmacist called Wilbur Scoville utilised the fact that piquance is due to capsaicin to create something called the Scoville Scale. This scale’s unit is 1 Scoville Heat Unit (SHU) and is proportionate to the level of capsaicin.
The following is a list of many types of chilli and their SHU:

  • Paprika: 0
  • Peperoncini: 100-150
  • Jalapeño pepper/Tabasco sauce: 2,500-8,000
  • Chungyang red pepper: 10,000-23,000
  • Habanero chilli: 100,000-350,000
  • Red Savina habanero: 350,000-58,0000
  • Naga Jolokia: 1,067,286
  • Naga Viper: 1,382,118
  • Trinidad Scorpion Butch T pepper: 1,463,700 (currently the world’s hottest pepper)
  • Tear gas/pepper spray: 5,300,000
  • Pure capsaicin: 16,000,000

Posted in Science & Nature

Bleach

Posted on by Jinavie

The most potent and frequently used household cleaning product is bleach. Bleach is a diluted solution of sodium hypochlorite (NaClO), which has powerful antimicrobial properties thanks to the element chlorine. This is also the reason chlorine is used to treat tap water and disinfect pools.

Although it is an extremely useful chemical, chlorine also has a very dark side. Chlorine gas is a highly toxic gas, which forms hydrochloric acid when breathed in and seriously burns the respiratory tract. Due to its toxicity, chlorine gas was used as a weapon of mass destruction in World War I. However, this terrifying gas can be made very simply at home. Unfortunately, this is often done accidentally (but sometimes on purpose) and causes significant damage.

The key warning for using bleach is that it must never be mixed with other cleaning products. If mixed with an acid cleaner, it causes a chemical reaction that produces chlorine gas, while mixing it with ammonia creates chloramine, another deadly gas (although dangerous in itself, chloramine can sublimate into chlorine gas too). Therefore, many people suffer a loss of smell, consciousness or their lives by accidentally mixing two cleaning products or cleaning up urine with bleach. A major problem is that these victims tend to be children who unknowingly mix the chemicals, creating a horrible accident. What is more unfortunate is that some people choose to end their lives using this method.
If you do find a person rendered unconscious by chlorine, it is imperative to quickly move them to a well-ventilated area, while not endangering yourself. An ambulance should be called right away.

As seen from above, simple chemicals found easily at home can produce toxic gases, which can cause irreversible damage. Thus, one must never mix bleach and cleaning products and should educate their children on the dangers of chlorine gas.

Posted in Science & Nature

Taste Of Water

Posted on by Jinavie

It is a common chemical fact that water is flavourless and odourless. However, most people will know that water “tastes” subtly different each time.
Taste is composed of information from taste buds on the tongue, combined with the sense of smell from your nose. Although water itself has no flavour or smell, it has many things dissolved in it such as gases and minerals that can be tasted.
This is why tap water can taste bad due to the chlorine used to treat it, or metals such as copper that have come off the pipes. 

It is also well known that temperature affects the taste of water. The ideal temperature is between 10~17°C, where oxygen saturation is sufficient, giving the water a “refreshing” taste. Any hotter and the oxygen escapes, giving the water a flat taste, just like distilled water. Warm water also causes the brain to think it is saliva or mucus, sometimes producing an uncomfortable sensation. Any colder, the tongue is numbed and it loses its ability to taste.

When making tea, the ideal temperature is 70~80°C. A simple way to achieve this is by leaving a cup of boiled water for a minute or two before putting the teabag in. This is the temperature when the dissolving of the various chemicals in tea leaves is optimal. If it is too hot, bitter-tasting tannins and catechins are released in excess, whereas if it is too cool, not enough dissolving occurs.

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Posted in Science & Nature

Mentos Coke Experiment

Posted on by Jinavie

There is an extremely entertaining experiment that can be done with two simple ingredients found in the local supermarket: Mentos mints and Diet Coke (it is more effective than original Coke). The experiment procedure is as following:

After opening the bottle, quickly drop the Mentos in to the Diet Coke. Run.

As soon as the Mentos falls in, the Coke spurts foam explosively, which shoots up to great heights. Depending on the temperature of the Coke (the warmer the better) and the number of Mentos mints (it is more effective to thread them and drop them all at once), the pillar of foam can rise to a few metres.

This fascinating phenomenon is not caused purely by a chemical reaction, but has more to do with physics. Mentos mints are coated with menthol, which has numerous microscopic dents. When it enters the Coke, the dissolved carbon dioxide forms bubbles that collect in these pits. As they collect, the bubbles expand until the pressure builds past a certain level, causing an explosion. 

The most important point is that if this experiment is not performed outside, one could end up cleaning a sticky room for days.