Important annoucement - Chemistry

Dear 3E2,

See you guys for extra lesson on 5 May (Wed) 2.30pm.

Jia you in your exam preparation!

Eat well and sleep well too!

Mrs. Yeoh

Wednesday, May 19, 2010

Physics (edited) by : Poh Wan Jie (17)

Q1) From the burning of fossil fuels to produce energy, green house gases are emitted which contributes to Global warming or the Green house effect. From the video, name some of the green house gases emitted by humans.

The green house gases emitted by humans are Water vapour , Mathane , Nitrogen Oxide .

Q2) How has global warming affect Singapore over the past 20 years? (Search the internet)

The planet faces great menace which is occurred by global warming. Global warming is an observable fact, but no one understands the level of its power on climate change. Due to the climate changes we all have now big problems like summers are getting very hot than ago year, winters are frieze than of previous years, and bad incident happens gradually. Further affect of Global warming is on to our coasts, our health, our energy and water resources, our agriculture, our transportation infrastructure, and our recreational resources due to the global warming.

Green house gases
There are numerous global warming affect on our climate, but the major affect is green house gases like carbon dioxide, methane, and nitrous oxide are playing vulnerability on our climate in the present times. There has been a noticeable rise in the average temperature of planet in the past century. This rise in temperature is credited to the effects of global warming brought about by the increase of greenhouse gases in the atmosphere. These green house gases catch heat in earth’s atmosphere and thus result in increasing the temperature of earth. They catch warmth release by the sun, heating earth. This process will make life on the planet possible. Natural greenhouse gases like carbon dioxide, methane, and nitrous oxide have always been in the atmosphere. Lack of this gas, world’s average temperature would be a chilly-18 degree Celsius. With the help of greenhouse effect we can enjoy an average temperature of 14 degrees on our planet.

Carbon dioxide (CO2)
Carbon dioxide is the number-one reason for climate change. The major source of carbon dioxide is the power plants. These power plants emit large amounts of carbon dioxide produced from burning of fossil fuels for the purpose of electricity generation. Carbon dioxide is the second-most important greenhouse gas behind water vapor. Methane and ozone are more efficient, but have less effect on climate change. Due to industrial revolution, the average amount of carbon dioxide in the atmosphere has been increased by nearly 40 percent. This increase in CO2’s share of the atmosphere is mostly due to burning fossil fuels, deforestation and industrial production. Mostly humans produce around 32 gig tons of carbon dioxide every year, fifty percent stay in atmosphere and remaining are absorbed by oceans and plants. The result of the increasing amount of carbon dioxide in the atmosphere is greenhouse effect and, next climate change.

Sea level rising
It depends on which greenhouse gas increase setting is used (high or low) for projected sea-level. Sea level has been rising at an average rate of 1.7 mm/year (plus or minus 0.5mm) over the past 100 years. It is considerably larger than the time averaged over the last thousand years. Sea level rise is projected to be anywhere from 0.18 (low greenhouse gas increase) to 0.59 meters for the highest greenhouse gas increase set-up. This increase is due to mainly thermal expansion and contributions from melting alpine glaciers.

Oceanic circulation changing
The oceans absorbed fifty percent carbon dioxide but highest levels of CO2 have led to ocean acidification. Furthermore, as the temperature of the ocean increases, they become less able to absorb excess CO2. Global warming is projected to have a number of effects on the oceans. Likerise in sea levels due to thermal expansion and melting of glaciers and ice sheets, and warming of the ocean. Other probable effects take in large-scale changes in ocean circulation.

Global Warming

Q3) You have just studied heat is transferred in 3 ways, conduction, convection and radiation. And you have some ideas on how to keep the classroom COOL in a hot and sunny day yet cutting down on the energy usage! * so air-con is out of the option *




We can paint our classrooms in colours or white colour that is a good reflector of light and also radiates heat quickly. This way we would not feel so much heat. Must not paint the classroom wall in black colour as it absort and emit heat very quickly . This way , it makes us feel hotter .We can use curtains to block out the heat.We must not close the doors of our classrooms so that air can come in. Otherwise, the classroom will be very stuffy and we would not feel comfortable studying. we should change all the bulbs into the energy-saving bulbs. This would obviously save the energy that is being used. With all this , We are able to study and learn well in an conducive enviroment !

Tuesday, May 18, 2010

Danial's physics

Singapore is a country surrounded by seas. Heavy rain is one of the consequences of global warming. The state controlled press tries to skim over it, by saying it is just unusually heavy rain. The truth is , unusually heavy rain will no longer be unusual.  Flooding will become an everyday occurrence.

 It is not because of bad drainage. The canals and drains there are deep and sufficient enough since a long time ago. The government has done everything they can to improve drainage. There is nothing more they can do. The problem is not drainage. It is global warming.
The sea level is rising at an unprecedented rate. When the suns rays hit the surface of the sea, the heat causing sea water temperature to rise. When the rays become hotter with global warming, the hotter the water gets. When water temperature rises, it expands. Simple physics. And when it expands the sea level rises  (video)
haiz...exam over alr...
regretted for not studying well enough...
scared to see the number of subjects failed in my report book.
just came back from ssc and bishan wit shuqing.
went shopping eating and crazys.
planned to go bugis with joanna yuxia and waiching.
but alr went there last few days so sian..
and no mood.
will see them back in sch tmr..
so bye now~
noticed that all my posts are getting shorter and shorter.
post the pics on next time.
tmr is mums' bdae...
maybe going out celebrate
hope my results wont be too bad and can make her happy instead of angry
promise will work hard!

Saturday, May 15, 2010


Q1) From the burning of fossil fuels to produce energy, green house gases are emitted which contributes to Global warming or the Green house effect. From the video, name some of the green house gases emitted by humans.

answer:The green house gases emitted by humans are Water vapour , Mathane , Nitrogen Oxide

Q2) How has global warming affect Singapore over the past 20 years? (Search the internet)

SINGAPORE — Surrounded by sea and almost pancake flat, Singapore is without doubt vulnerable to the rising sea levels many scientists predict global warming will cause.
While topographical maps are considered a military secret here, anyone flying into Singapore can easily see that the island is elevation-challenged. Its highest point is a jungle-clad hill rising 165 meters, or 540 feet, above sea level. Most of the business-end of Singapore - its airport, its business district and, of course, its busy container ports, lie less than two meters above sea level.
Faced with the prospect of a long, slow submersion into the very waters that serve as the lifeblood of this maritime trading hub, Singapore has reached out to the world's greatest experts on the subject of battling back the sea - the Dutch.
"We are already in consultations with Delft in Holland to learn how we can build dikes," said Lee Kuan Yew, the former prime minister, in an interview last Friday.
Delft Hydraulics, a research institute and consulting firm specializing in water management issues in the canalled Dutch city of Delft, is already helping Singapore convert its biggest river and marina into a huge downtown reservoir. Now it is also helping the city-state look into just what it can do to defend its roughly 200-kilometer, or 125-mile, coastline.
"We feel we have strong reasons to be concerned, but no reasons for panic," said Vladan Babovic, director of the Singapore Delft Water Alliance, a $43 million research center opened in February between Delft, the National University of Singapore and the country's water management agency, PUB Singapore. "We will be able to resolve these challenges," he said.
Singapore got a preview of just what havoc rising sea levels could cause back in 1974 when a rare astronomical event caused the tides to rise 3.9 meters, more than double the usual level.
"It eroded the coast very badly," said Wong Poh Poh, an associate professor specializing in beach geography at the National University of Singapore, who studied the event. Areas along the Singapore River were inundated, as were parts of the airport and a coastal public park built on reclaimed land.
Wong later discovered that during such periods of elevated sea levels, the variations between high and low tide are accentuated, putting the country's reservoirs, many of which lie adjacent to the coast, at risk. Singapore officials later used one of Wong's reports to draw the attention of the United Nations to the problems associated with global warming.
Still, no one is certain just how much of Singapore is vulnerable to the problem. The Singapore Delft Water Alliance and researchers at the national university's Tropical Marine Science Institute began a study into the potential effects of climate change on Singapore in March. But the leader of that study, Liong Shie-Yui, said that the group had yet to produce any noteworthy findings.
Assessing the risk is complicated by the fact that no one knows for sure just how much the sea may rise or how fast. Estimates vary from as little as 60 centimeters, or about 24 inches, to as much as 6 meters. And sea levels are not consistent from place to place: atmospheric pressure, wind and currents can cause variations.
Ultimately, Singapore is unlikely to build dikes per se, but rather concrete seawalls, Babovic said. Dikes are technically made of earth. After digging up and quarrying much of its own interior to reclaim new land that has increased Singapore's area by between 15 percent and 20 percent, Singapore now relies on imported landfill and sand for its reclamation efforts and to produce cement for new buildings.
Many scientists believe that dikes are no longer the most environmentally sensitive solution. Wong recommended docks and seawalls back in the early 1990s but now said that more natural structures might work better.
Babovic said that scientists were studying ways to incorporate mangroves and sea grasses into the design of dikes and seawalls to improve their environmental impact and make them look better, too.
"You need more imaginative solutions," said Wong. "What we don't want is to put something there that will constrain future use."

Q3) You have just studied heat is transferred in 3 ways, conduction, convection and radiation. And you have some ideas on how to keep the classroom COOL in a hot and sunny day yet cutting down on the energy usage! * so air-con is out of the option *
answer:use energy saving fan....and paint the classroom whiten so that the room wont radiate sooo much heat....but still i think that the air con is the best way.

Friday, May 7, 2010

option 2- hair rebonding

How hair rebonding works to straighten your hair from your natural curl? What occurs to the structure of hair when rebonding treatment takes place? What happens to the keratin in the hair during rebonding? What is/are the chemical(s) involved to re-structure your hair, to make it straight? Is it harmful?

during rebonding, the chemical bonds of your hair are broken. then they are rearranged and bonded back again permanently. this makes the rebonded hair remain straight while the newly grown hair will be in its original state. during the process, your hair can burn if ithe temperature is more than 180degrees. you can also experience baldness after afew years of regular rebonding. this is because your hair becomes weak and can break easily.there will be also a bad smell coming out
from the keratin while the rebonding is in process

Thursday, May 6, 2010


when the onion skin is broken, it releases a substance called propanethial sulfoxide, which is similar to sulfuric acid.So the nerve endings in your eyes detects the propanethial sulfoxide and your brain tells your eyes to produce tears to wash it scientist have created an onion without the cell with the  propanethial sulfoxide.It’s still in the development innovative way is to put a small fan beside the onion so that the propanethial sulfoxide will not reach our eyes. another way is to freeze the onion so as to deactivate the cell with the propanethial sulfoxide

DAN'S chemistry

According to the webpage that i found, onions contain amino sulfoxide which can irritate our eyes and make it tear. The one that causes our eyes to tear is the lachrymal glands above our eyelids that regulate the release of tears. Ity also triggers our nerve of crying to our brain which will then make our eyes cry. One of the ways to prevent our eyes from tearing is by covering it with a safety goggle. :) another way told by a guy was: NO more tears? try chilling your onion.  

Wednesday, May 5, 2010

Option 3: Onions

When we cut onions, its not the odor that makes us cry, but the gas that is release when we cut onions.
Onions contains oil, which contains sulfur, both an irritant to both our nose and our eyes.Cutting the onion will produce a gas called propanethiol s-oxide.This gas will mix with the enzymes in the onions and will produce a sulfur compound.The sulfur compound will react with the water in our eyes to produce sulfuric acids.
Our eyes will automatically blink and produce tears which will flush out the sulfuric acids from our eyes.

One way to prevent crying when cutting onions is to cut it underwater.The water will dissolve the sulfur and will not be able to have contact with our eyes. The water will also draw out the juice.Another way is to cut it with a sharp knife.If you cut it with a blunt knife,you will crush the onion and not slicing it.Crushing the onion will produce more of the gas.You can also wear goggles and mask when cutting onions.Rubbing our eyes will only makes things worst. This is because your hand contains the onion juice and the sulfuric acids.

Syazrin 3e2

Why Do Onions Make Us Cry???

Why do onions make us cry?
Most of us think that the reason why our eyes sting when we cut onions is due to the very strong odour of the onion. However, this is not really true. What is the answer then? Well, our eyes cry because of the gas that the onion releases when we severe it, propanethiol S-oxide.
The onion itself contains oil, which contains sulfur, which likes to irritate both our noses and eyes. Cutting an onion arouses propanethiol S-oxide, whi
ch then couples with the enzymes in the onion to emit a passive sulfur compound. When this upwardly mobile gas encounters the water produced by the tear ducts in our eyelids, it produces sulfuric acid. In response to the acid, our eyes automatically blink, and produce tears which irrigate the eye, and which flush out the sulfuric acid.
Another reflex to rid the eyes of a foreign substance, that of rubbing our eyes with our hands, often exacerbates the situation, because our hands are coated with the caustic, sulfuric acid producing oil from cutting the onion, which we then rub directly into our eyes.

How do we avoid crying when cutting onions?
The only remedy for ridding the onion of its pungent and irritating oil is to boil it.
Another way is to wear protective glasses so that not much of the gas may enter the eyes.
Also, we can usually wash our eyes, even though it may cause to be a nuisance.

Done by: Siti Farina

Monday, May 3, 2010

Hair Rebonding
generally , Our hair curls because of there is sulphur bonds in our hair. Rebonding will break down the sulphur bonds by heat and chemicals. During rebonding, keratin is added on the surface of the hair. Interferon alpha is a drug used to modify hair follicles and is used in rebonding but it only damages the hair texture. Neutralizers are used to stabilize the hair. rebonding requires at least 3 hours to complete and its is expensive depending on the length of our hair. nowadays , alot of ladies and even guys go for rebonding as people get more vain in nowadays. although reonding is nice , it also damages our hair.

Thursday, April 22, 2010

Hair rebonding

Hair rebonding soften, smoothen and straighten the hair. Most people wants their hair to be rebonded because they want they hair to look shiny and have a smooth like appearance. Keratin in our normal hair contains protein high in sulphur and amino acid cysteine. These chemical substances makes the keratin able to keep our normal hair strong and natural.
During rebonding, cream softener is used to break the hair structure. Then, a neutraliser is used next to straighten the hair again. The chemical use for hair rebonding affect the hair structure and its quality. The normal hair usually has keratin to keep the hair strong, however, when hair rebonding happens, the hair becomes weak tends to cause problems. Such example would be the loss of hair.
Hair rebonding is harmful. Although it gives you the appearance of hair a person would want, however, in reality, it only destroys and damage the hair structure and leads to more problems. If too much chemical is used during hair rebonding, it can damage the hair to the extend that the hair would become dry and or even hair loss.

Rachel - 3E2
Option 3: Onions.
Why do onions make you cry?What is 'happening' in your eyes? What is/ are the chemical compound(s) that cause you to tear? How can you make onion-dicing less problematic?

Onion is just like other plants. It is made up of cells which are separated by membrane into two parts. One part contains enzymes while the other part contains the molecules that consist of sulfur compound. When the onion is cute, some onion cells break open and the contents (enzymes and molecules that consist of sulfur compound) of membrane mix together. The enzyme causes the sulfur compound, amino acid sulfoxides to undergo a few chemical reactions. Sulfenic acids are formed, which are immediately coverted into a volatile gas, propanethiol S-oxide. The gas gets in contact with your eyes and reacts with the water present in the eyes. Certain chemical changes are taken place inside the eyes and a mild sulfuric acid is formed. This causes irritation of the eyes. Your eyes twinge while cutting the onion because the nerve endings in the eyes are very sensitive. The tear ducts in the eyes produce more water in order to dilute the irritating acid. However, this is good as the eyes are protected.

The irritation can be prevented by cutting the onions by different ways. One of the easy ways is to keep your head as far away from the onion as possible. Gas will mostly disperse before it reaches your eyes. Another simple way is to wear goggles. Another way is to peel the onion and chill t in the refrigerator before cutting, then it woud minimize a release of gas. This is because a change in the temperature alters the compounds present in the onion. You can also cut the onions under water or run the tap over the onions as you cut it.



When we cut onions, we break the cells releasing all their contents making amino acids sulfoxides form sulfenic acids. The enzymes that were separated are now able to mix with the sulfenic acids, thus producing propanethiol S-oxide. Propanethiol S-oxide is a volatile sulfur compound that noves upwards to our eyes. The gas reacts with the water in our eyes. Certain chemical changes take place in the eyes and there is the formation sulfuric acid. This sulfuric acid burns your eyes releasing tears to wash the irritating substance away. One way in which we can prevent the tearing of our eyes is by keeping it cool in a refrigerator before taking it out to cut it. this slows down the reactions and changes the chemistry in the onion. Another way of avoiding the tearing of the eyes is by cutting the onion under running water. Lastly, when cutting an onion, avoid the roots as it has a higher concentration of enzymes.

Science Chemistry Networking Project - Onion [Vincent]

Question:Why Do Onions makes us cry?What is happening in our eyes?What is/are the chemical compound(s) that cause you to tear?How Can you make onion-dicing less problematic?

Actually when onion make us cry , it is not the strong odor that makes us to cry but the gas that releases from the onion when we cut it.

The onion itself already contain oil in it which contain sulfur which irritant our eye and nose.
When we cut the onion, it will actually produce a gas called Propanethiol S-Oxide.

This gas which will combine with the enzymes contains inside the onion and emit a passive sulfur compound. The passive sulfur will then travel upwards to your eye and when it encountered the water in our eyelid produced by our tear ducts , it will then produce sulfuric acid.

These caustic acid makes our eye blink automatically, to protect from these caustic acid , your brain will tells your eye duct to produce more water so that it will dilute the irritating acid and the sulfuric acid will be flush out.

We can make onion-dicing be less problematic.There are actually 2 ways you can do it, the first way is that you chop the onion under cold water so that when the passive sulfur compound is produced out , it will react with the cold water first instead of reaching your eye.

Another way is that before you cut the onion, you freeze the onion for 10 minutes. By doing this, it will coolder the temperature of the onion and it will slow down the chemical reaction which form the passive sulfuric compound.This will also slows down all the activities of the enzymes.

By Vincent.



Why do onions make you cry? What is 'happening' in your eyes? What is/ are the chemical compound(s) that cause you to tear? How can you make onion-dicing less problematic?

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

Here are ways to make onion-dicing less problematic. 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.Here are some videos url which show how onion dicing can be less problematic and more tears? Try chilling your onion before cutting it.

Done by adrian(23)3e2

Science(chemistry)-Networking Project

Q1.Why do onions make you cry?Q2.What is 'happening' in your eyes? Q3.What is/ are the chemical compound(s) that cause you to tear?Q4: How can you make onion-dicing less problematic?

A1:According to my research,Our eyes automatically start blinking and producing tears because of the irritants like chemicals such as sulfenic acids which produce a pungent odor which is converted by the LF-synthase enzyme into a gas called syn-propanethial-S-oxide, also known as the Lachrymatory which is also known as a crying factor

A2:Our eyes started to cry as it force / flush the chemicals that are received by our eyes out.

A3:As what i answer in question 1, it contains sulfenic acids, which is converted by the LF-synthase enzyme into a gas called syn-propanethial-S-oxide which is also known as Lachrymatory or crying factor.

A4: According to my research,there are lot of ways to make the onion-dicing less problematic. One way is to put them into the refrigerator to reduce the gas that it releases. Secondly, Cut fast!, and there more, like: put a slice of bread in your mouth, chew a gum while dicing and even dicing the onions with the help of running water.

Here is the link to the video which further improve our understanding about the question:

Done by: Ralph Joshua(34)
Class of 3e2

chemistry-hair rebonding

Hair Rebonding
Our hair is curly because of the sulphur bond of our hair. Rebonding simply break down the sulphur bond by heat and chemicals. During rebonding, keratin is added but it is only left on the surface of the hair instead of being the internal part of the hair naturally when it grew. Interferon alpha is a drug used to modify hair follicles and is used in rebonding but it only damages the hair texture. Neutralizers are used to stabilize the hair. A lot of money and time is needed to put in to maintain a rebonded hair. For example, it needs to be oiled, and it has to be redone whenever our hair grow to touch up any unneccessary curls.

Q3 Onion

It is because as we cut the onion, the onion itself contain oil. The gases release by the onion obtain sulfur which irrate our eyes and nose. When the gases Propanethiol S-oxide, is released and it rise upward encounter the water produced, the tear ducts is automatically blink, and produce tears which irriate the eye, and flush out the sulfuric acid in our eyelids, it produces sulfuric acid. In response to the sulfuric acid, our eye blinks and produce tears which irrate our eyes. Our tears contain the sulfuric acid. Thr chemical are Propnethiol S-oxide, sulfur , sulfuric acid and amino acid.
First we should put our onion in the cold water so the volative sulfured compound will react to the water. Then we froze the onion before cutting so the chemical reaction would be slow down.

Option 2 : hair rebonding

Rebonding is a chemical hair treatment that makes your hair straight, sleek and shiny. It is a permanent and expensive procedure. Prices for the treatment may vary across salons due to products used, service, your hair type and post treatment care. Each type of hair has a natural bond.Curly or wavy, are the result of natural bonds that give the hair its physical quality. The cream softener or relaxant used in the rebonding treatment breaks the hair structure. Then a neutraliser bonds the structure again and makes hair straight. In simpler terms the rebonding treatment changes your natural hair structure and restructures it. Once your hair is straightened you have to touch up the new growth every three months, six months or a year, depending upon your growth. Very strong chemicals are used to alter the structure of the hair, to break down its bonds (this is what gets rid of the curl) and to ‘rebond’ it again using chemicals to keep them straight. After shampooing, a cream softener or relaxant is applied to every hair shaft, keeping it thin plastic board. The hair is then steamed for 10 to 40 minutes, depending upon hair type and condition, and then rinsed. Hair is blow dried and then keratin lotion is applied and then it is ironed to further straighten it. Lastly a neutralizer is applied and kept for at least 30 minutes. After this procedure, one is not allowed to wash or tie back or even wet the hair for a few days. Even afterwards, you have to be extremely careful with your hair, since the rebonding process renders the hair shafts weak and very prone to breakage. You need to use a hair conditioner and hair serum regularly. It is also advisable to oil hair and to use a hair masque at regular intervals. If inferior products are used or you have the misfortune of going to an untrained professional, rebonding can go disastrously wrong and seriously damage hair, in extreme cases also sometimes results in hair fall and bald patches. So if you are considering hair rebonding, arm yourself with the knowledge of the possible pitfalls and the fact that you will have to take extra care afterwards. Any chemical process affects hair texture and quality. Excessive use of chemicals makes hair dry, weak and can even lead to hairfall. Hair rebonding requires post treatment care otherwise it may turn harmful. If you are suffering from hairfall, you must avoid rebonding or any other chemical hair treatment. Cheap chemicals, inexperienced hair stylists and weak hair can make rebonding a bad experience. Hair rebonding can turn into a disaster if you do not take care of your hair. Hair will need extra pampering once it has been rebonded. You cannot ignore your hair just because it looks straight and shiny. Rebonding done from a reputed and trustworthy salon lasts longer and hair quality does not suffer.

3) Onions

When we cut the onion, we cut through the cells, releasing their contents. Amino acid sulfoxides to form sulfenic acid. Enzymes that were kept seperated now are free to mix with sulfenic acid to form a volatile sulfur that reacts with your tears to form sulfuric acid, making your eyes "cry". The chemicals are amino acid, sulfenic acid, propanethiol sulfuric-oxide and sulfuric acid.
First, we can chop the onions in cold water so that the volative sulfured compound will react with the water but not our eyes. Second, we can freeze the onion for 10mins before cutting. It will slow down the chemical reaction of the volatile sulfured compounds.


Why do onions make us cry?
Like most other plants, onion is made of cells. These cells are separated by a membrane into two sections. One side of the membrane consists of enzymes, while other side contains the molecules that consist of sulphur compound. This is because when you cut the onion, a number of onion cells break open and the contents of both sides of membrane mix together and it would release a gas that will cause us to tear.This is because the onion contains oil, sulfur which will irritate both our eyes and nose.This causes a chemical interaction, a substance called prophanethiol s-oxide with the enzymes in the onion will emit a passive sulfur compound.

What happens in our eyes?
When this gas reach the water in our tear ducts in our eyelids, it would release a sulfuric acid.The nerve endings in the eyes are very sensitive and hence, your eyes twinge while cutting the onion.Our eyes would automatically blink and produce tears to flush out the sulfuric acid. This would also cause a burning sensation in our eyes. The brain would also send signals to the eyes to produce more tears.
What is/are the chemical compounds that cause us to tear?
The chemical compounds are synthase enzyme that converts the sulfoxides (amino acids) of the onion into sulfenic acid. The unstable sulfenic acid rearranges itself into a volatile gas, syn-ropanethial-S-oxide.

How can we make onion dicing less problematic?
As the onion has a pungent smell which will also irritate our eyes, we can try boiling it instead of directly slicing or dicing it first. We can also cut the onion under water as the water would wash away most of the sulfuric compound. Peeling the onion and storing it in the refrigerator before chopping may also help as the temperature change would be altered. Some people also tried biting a slice of lemon or bread may help to keep us from crying when cutting an onion. Wearing safety goggles may sound ridiculous but people wear it to prevent themselves from tearing too!

Option 1: Antiperspirant VS Deodorant

Definition and causes of body odor

Body odor is a perceived unpleasant smell our bodies can give off when bacteria that live on the skin break down sweat into acids - some say it is the smell of bacteria growing on the body, but it really is the result of bacteria breaking down protein into certain acids. the body. These bacteria multiply rapidly in the presence of sweat. Sweat is actually odorless; it is bacteria that live off perspiration on our body that create the bad smell.

Types of acid contain in the body odor .

Propionic acid and Isovaleric
acid is found in the sweat. These two types of acid are commonly present when there is body odor. Also , there are two types of sweat glands : Eccrine glands and Apocrine glands.Humans generate apocrine and eccrine sweat. Eccrine sweat is used to lower our temperature, like when we exercise or when it's really hot. It is produced uniformly all over the body and does not smell.

Apocrine is a special type of exudation that is produced in places like the armpits, groin, hands, and feet. It is the latter that causes all the trouble, but like eccrine sweat, it also doesn't smell. Apocrine perspiration simply contains fat and protein.

How does apocrine sweat tend to make us stinky?

Some bacteria on our body feed off apocrine sweat. Once they consume the sweat, they do what any living creature on earth does: they defecate . B.O. is the smell of bacteria excrement!

Actually, bacteria don't really defecate like we do -- they break down chemical bonds -- but they do consume our perspiration, and that makes us smell.

Causes of body odor also due to inadequate bathing (and/or cleaning/washing of clothes). It is caused by skin bacterial activity on sweat which has dried on the skin - and this makes people who sweat excessively more likely to be affected. In some people (the excitable 'greyhound/racehorse' types) the sympathetic aspect of the nervous system is dominant and they tend to sweat more, whereas in others (the calmer 'bulldog/carthorse' type) the parasympathetic aspect dominates and they tend to stay calmer. So keeping stress levels low is important for people who sweat a lot.

Antiperspirant vs Deodorant:
The variation most commonly used in deodorants and antiperspirants is Al2Cl(OH)5. Aluminium chlorohydrate is one of the most popular active ingredients in commercial Antiperspirants.

Types of Antiperspirant Deodorant

Deodorant kills bacterial through a number of ways. It may be a spray or aerosol product that contains alcohol that will temporarily kill bacteria. It might be a roll on or gel that contains an antimicrobial metallic compound. There are roll on deodorants made with naturally anti-microbial hops.It doesn't prevent you from sweating, but prevents bacteria from thriving on body parts where you sweat. A chemical called triclosan makes the underarm skin too acidic and that prevents your armpit from becoming a home to the bacteria, thus, reducing chances of bad odor.

spirant – uses various forms of aluminum to block the production of sweat. Aluminum reacts with compounds on the surface of your skin to form a kind of plug that blocks your pores.Antiperspirants differ from deodorants in that they don’t just mask the odor, but actually block the skin pores so that moisture isn’t released. The active ingredient that does this is an aluminum based compound that blocks the pores by forming a gel-like plug. Not only does this gel-like plug reduce odor, but it also keeps your underarms dry so you won’t stain your best white usually has a fragrance to make the user smell good. The association between exposure to aluminum and long term use of antiperspirants and Alzheimer's disease is a trend toward a higher risk with increasing frequency of use.

Deodorants or antiperspirants: Which is best?

While it may seem as if an antiperspirant would be the obvious choice since it has the dual function of reducing odor as well as keeping you drier, antiperspirants have been the subject of some health scrutiny. Aluminum compounds, like those found in antiperspirants, have demonstrated harmful effects in animals and are thought to be toxic to nerves and, possibly, to the kidneys.
However ,aluminum compounds used in the antiperspirants can get assimilated in the blood stream and cause serious health issues.

While deodorant can mask the odor temporarily, it cannot stop a person from sweating the way an antiperspirant does. Once the sweat combines with odor causing bacteria, the underarms will begin to smell again.


Deodorants and antiperspirants are used to stop the smell of body odor that is created by a combination of bacteria and sweat.Deodorants attack odor causing bacteria to eliminate smells whereas antiperspirants prevent your body from sweating and therefore keeps you both dry and smell-free.To compare which is the safer to use ,the answer will be Deodorants .Deodorants are considered to be safer than antiperspirants because they don’t stop the body’s natural method for cooling down.

Wednesday, April 21, 2010

CHEMISTRY - Option 1: Antiperspirant VS Deodorant


There are many causes which will leads to body odor. Some examples are – diet, gender, occupation, mood, health, medication and genetics.

Occupation and mood: wrecked promotion prospects at work, educational under – achievement because of teasing and bullying along with huge degrees of stress which is blamed for their frequent progression into alcoholism, immoderate tobacco or drug use in some cases to suicide.

Health: sometimes may be link with fixed health problems such as liver dysfunction, diabetes, digestive problems (parasites, etc) and yeast infections.

Diet: If the lively micro-organisms are unbalanced through use of medication (antibiotics and steroids in particular) or a high fat, high sugar, high red-meat, low fiber diet the lively role they play in detoxification of the bowel and in manufacturing important nutrients is impaired and this can exacerbate the condition of body odor, as well as to numerous other health problems.

Gender: In women, menstruation and stress often cause dramatically increases the degree of body odor experienced and careful attention to personal hygiene and dietary excellence is needed.


· Antiperspirants contain fragrance and contain a chemical compound that blocks the pores to stop the discharge of perspiration. There will be NO sweat, NO odor.

· Deodorant allows the release of perspiration, but prevents odor by combating it with antiseptic agents, which kill odor-causing bacteria.


Perspiration itself is almost unscented. Most of the odor that accompanies perspiration is caused by the action of bacteria. Deodorants reduce this odor in one of the three ways: by preventing the action of bacteria on the perspiration, by preventing the secretion of perspiration, or by masking the offensive odor with a pleasant one.

Deodorants that kill or inactivate bacteria contain antiseptic substances, such as alcohol, formaldehyde, and boric acid. Chlorine compounds, e.g. hypochlorite and chlorhexidine, work by killing bacteria which may be responsible for the odor. Deodorants that mask perspiration odor contain perfumes. Essential oils and such disinfectants as carbolic acid simply mask the odor, making it less offensive.


Deodorants that prevent the secretion of perspiration are called antiperspirants. They usually contain an aluminum salt, such as aluminum sulfate, that acts by blocking the pores preventing the free flow of sweat.

Aluminum-based antiperspirants work by blocking the sweat ducts, thereby reducing the amount of sweat that reaches the skin’s surface. Aluminum salts are soluble as long as the formulation is acidic (low pH). When they are applied to skin and come in contact with sweat, the pH rises causing the aluminum salts to precipitate out and form a plug over the sweat glands. Sweat continues to be produced by the sweat gland but it just isn't able to reach the surface of the skin.

Diphemanil methyl sulfate is a drug that opposes the action of the parasympathetic nerves that control sweat production.


Healthcare professionals recommend deodorant over antiperspirant as they believe that obstructing pores and preventing perspiration may not be the healthiest choice.

Aluminum compounds or aluminum salts, such as aluminum oxide (Al2O3), are key ingredients in almost every antiperspirant. They are powerful astringents that close pores, stopping sweat and odor from escaping the body.

The active ingredient of the product consists of any of the following within the established concentration and dosage formulation. Where applicable, the ingredient must meet the aluminum to chloride, aluminum to zirconium, and aluminum plus zirconium to chloride atomic ratios described in the U.S. Pharmacopeia-National Formulary. The concentration of ingredients in paragraphs (b) through (j) of this section is calculated on an anhydrous basis, omitting from the calculation any buffer component present in the compound, in an aerosol or no aerosol dosage form. The concentration of ingredients in paragraphs (k) through (r) of this section is calculated on an anhydrous basis, omitting from the calculation any buffer component present in the compound, in a no aerosol dosage form. The labeled declaration of the percentage of the active ingredient should exclude any water, buffer components, or propellant. Sweating is nature’s way of lowering the temperature of body and prohibiting this by blocking the pores is not ideal. Also, the aluminum compounds in the antiperspirants are not healthy friendly stuffs. Antiperspirant increases danger of breast cancer, especially if it’s applied their underarms.

Deodorants contain parabens which believe to cause breast cancer.