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!

Cheers,
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 *

Conduction









Convection






Radiation














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

http://www.youtube.com/watch?v=oJAbATJCugs  (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!
JiayouS!

Saturday, May 15, 2010

physics

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

ONION ANSWER BY razy

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 away.now scientist have created an onion without the cell with the  propanethial sulfoxide.It’s still in the development stage.one 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
3e2

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.