Commendation

Hi, everyone,

A new year has started. Before you move on, lets congratulate those who have worked hard last year!




Happy New Year! Continue to do well in Chemistry.

Biofuel Development Shifting From Soil To Sea

Hi, all,

Some of the classes watched a video discussing about biofuel.

As can be seen from the video, biofuel has its benefits and disadvantages.

Now, instead of food crops, people are looking to using algae as a source of fuel. Read this to find out more!

Guiding questions:
- Why is algae a good alternative?
- Are all algae species useful?

Enjoy your holidays!

Picture from ScienceDaily

Teachers' Day 2009

Hi,

Must thank all for a great Teachers' Day celebration.

This is the tribute this Monarchy has collected this year. Some of the gifts are rather unique: a self-made photo frame, a pen craved out of twig, etc..

Thanks to all, even if there wasn't any gift. Words of encouragement are actually all that is needed.

Enjoy your holidays!

Cheers,
Mr Koh

From 4A

From 4M, 4R & 4RA

From 4T

Catalysis - Size Matters

Hey,

We have done catalysis in rate of reaction and we know that the size of the particles does affect the rate. However, does the particle size of the catalyst matters?

Read this to find out more.

Picture from The Future of Things

Metals and Corrosion

Yoz,

We have finished the topic on Metals and Corrosion.

In the topic, we briefly mentioned that salt water will promote corrosion. Do you know that this simple phenomenon has applications in forensic investigation? Read this for more information.

In addition, some of you asked why in a electric cell, the displacement occurred at the less reactive electrode. E.g. when put into the lemon, effervescence occurred at the copper electrode and not at the zinc. There is an explanation offered at this website.

Enjoy!

Picture from University of Leicester

Commendation

Dear all,

Here's the first ranking of the year.

While the results are commendable, there is definitely room for improvement.

Work harder. There is still a long journey ahead.

Chemical Analysis

Yoz, everyone,

Since you have 2 'free' days, I think you can afford some time to do some reading.

As I've mentioned in class, there are 2 types of chemical analysis - Qualitative (what?) and Quantitative (how much?).

In class, you've learnt chemical methods to detect ions. But, what are some limitations of these tests? How to chemists overcome these limitations?

To help detect really small quantities, machines have been invented. One such machines is the Atomic Absorption Spectrometer (AAS). The AAS not only identifies the metal (e.g. elemental or ionic form) present, but also tells the quantity that is present. Read this for more.

Those who are keen to find out more about analytical chemistry, you could read this. It includes the various work done by analytical chemist.

Enjoy ur weekends!

Picture from Université de Montréal

Rain rain come this way!

Hi.

In class, we discussed the importance of salts. Do you know that salts (like silver iodide and calcium chloride) are used in cloud-seding to cause rain to fall?

Quite an interesting technology that you might want to read up. What happens to the salts as they fall onto the ground? Will they cause pollution? Read this for more.



Picture from WET International

Periodic Table

Hi, all,

This week, we have gone through very briefly the development of the Periodic table. You might want to check this website out for more details.

There are many elements out there and they possess many interesting properties. One which you are very familar with is Hydrogen. Watch the following movie about Hydrogen:



Many more videos about the elements have been made by the University of Nottingham. Check them out!

Enjoy!

Cya guyz soon. Enjoy watever is left of the hols!

Accolades IV

Yoz everyone,

After a year of hardwork, we have survived this year.

Let's celebrate the success together!

Accolades III

Hi, all,

This is the ranking for the CA.

Congratulations to all. Do work harder for the coming EOY. Remb our aims!

Application of Redox - Photochromatic lens

Hi,

You must have noticed that some of your friends wear glasses whose lenses change opacity under different lighting.

Nope, they are not from Hogwartz (unlike me, haha). This is the work of Redox Chemistry.

Basically, in their lenses, called photochromic lenses, silver chloride (AgCl) and copper(I) chloride (CuCl) crystals are added during the manufacturing of the glass while it is in the molten state and these crystals become uniformly embedded in the glass as it solidifies.

One characteristic of silver chloride is its suscepitibility to oxidation and reduction by light as described below.



The chloride ions are oxidized to produce chlorine atoms and an electron. The electron is then transferred to silver ions to produce silver atoms. These atoms cluster together and block the transmittance of light, causing the lenses to darken. This process occurs almost instantaneously. As the degree of "darkening" is dependent on the intensity of the light, these photochromic lenses are quite convenient and all but eliminate the need for an extra pair of sunglasses.

The photochromic process would not be useful unless it were reversible. The presence of copper (I) chloride reverses the darkening process in the following way. When the lenses are removed from light, the following reactions occur:


The chlorine atoms formed by the exposure to light are reduced by the copper ions, preventing their escape as gaseous atoms from the matrix. The copper(I) ion is oxidized to produce copper(II) ions, which then reacts with the silver atoms as shown.


The net effect of these reactions is that the lenses become transparent again as the silver and chloride atoms are converted to their original oxidized and reduced states.

Q. Identify the oxidising agents and reducing agents in both Eq 1 and 2.

Adapted from Oxidation/Reduction by Kapi'olani Community College.

Thanks!

Yoz guyz,

Thanks for all your cards, gifts, words of encouragement:



Enjoy the Sept hols, but dun forget to mug for you-know-wat-is-the-most-impt-subject.

Be prepared for presents from me via emails.

Cheers,
Mr Koh

Nitric Acid - A special one

Yoz,

We have been working on Acids for some time now.

What we know is that acid reacts with reactive metal (e.g. Zn, Mg, Ca) to form salt and hydrogen. The unreactive metals (e.g. Au, Cu) do not react with acids.

However Cu does react with nitric acid. Why? Because nitric acid is an oxidising agent as well. Read more about the nitric acid here.

Some terms you would be familiar would be: strong acid, acid concentration, etc.

You could also read about the 'strongest' acid which scientists have made. (see here) How is this acid contradicting what we discussed in class?

Carborane, part of the world’s strongest acid. [Atom color code: orange = boron, gray = carbon, green = chlorine, white = hydrogen.] Picture from ScienceDaily.com

Accolades II

Hi, all,

This is the ranking as of present (70% of RP CA and 37.5% of RA CA is included in computation).

Congratulations to all. Let's work hard to make the list longer!

Methane - Solution to the Rising Fuel Cost

Hi,

Recently, the local paper reported that more of our cars are being converted to ones driven by CNG (compressed natural gas). For those who still do not know what CNG is chemically, it is methane. The driving force to convert is that CNG is much cheaper when compared to the petrol. However, the price of CNG is also rising. Why? Think about it.

Actually the ground is not our only source of methane. We can get it from guts of cows, sheep, and maybe you!

In the 1960's, scientists found high levels of methane near the ocean’s oxygen-rich surface, which is unusual. Why is it unusual? Don't tell you now.

Now they have uncovered the reason behind this. To know more, read this.

Who's interested in working on this for RE? Maybe we could be the next millionair?!

Super Atoms

Hey. So long never blog liao.

Well, since there's really not much new research in the area of Mole Concept, let me post you a question regarding this topic:

Why was there only 1 Avogadro? (see Comments for answer and souce.)


Anyway, there is now such a thing call super atoms. It was found by researchers that metal atoms will form clusters in vapor phase and behave like another element. Want to find out more, read this.

Cya around.

Picture from ScienceDaily.com

Lavoisier

Yoz,

The hols is coming to an end soon.

Btw, do remember to submit your Lavoisier Assignment when school reopens. And don't be like someone who is trying to get the answer from yahoo.answer. And the person who replied is NOT me. =)

Anyway, here's one good book you might want to read:

A World on Fire - A Heretic, an Aristocrat, and the Race to Discover Oxygen by Joe Jackson.

It talks about Lavoisier and another scientist Joseph Priestley.

Enjoy!

Picture from Lukeman.com

Mole Concept - Word Search

For those who are too boliao, you can test your understanding of mole concept here!


Puzzle from Oklahoma State University
Enjoy!

p.s. why is the molar gas volume different from ours? I thought it should be 24 dm3? Do not be confused ok!