2009-06-23

Fluoride in Toothpaste


Photo taken show ingredients in a type of toothpaste.
Sodium lauryl sulphate is a type of detergent that helps in cleansing our teeth.
Sodium fluoride(NaF) and sodium monofluorophosphate (Na2PO3F) are active ingredients to prevent cavities.

Biodegradable Plastics?

Biodegradable plastic bag from Jusco..

Another one from Tesco...









Both Jusco and Tesco uses biodegradable plastics and encourage their customers to to reuse the plastic bags.

I just found out from news paper, IKEA is no longer provide free plastic bags for its customer. It'll be charged upon customers' request.
I hope with the effort of these giant hypermarkets, the public will reduce the usage of plastic and choose more environmental friendly alternatives. Save our mother earth from plastic...

Detergents and additives

The photo was taken from a type of detergent used to cleaning cloths.

Detergent is a salt formed from the reaction between an alkyl hydrogen sulphate and an alkali.

















Additives are added to make detergent more effective in cleaning.

Examples of additives that can be recognized are:
Optical whitener:
stabiliser:
fragrance:

Funtion of different types of additives in detergent:
  1. biological enzyme : remove protein stains such as blood. E.g. amylase, proteases, lipase.
  2. whitening agent(include bleaches): convert stains to colourless substances, thus make clothes whiter and cleaner. E.g. sodium perborate and sodium hypochlorite
  3. optical whitener: make white clothes look whiter. E.g. fluorescent dyes
  4. fragrances : add freagrance to fabrics.
  5. drying agent: ensure the detergent powder is always dry. e.g. sodium sulphate & sodium silicate
  6. stabiliser : control foaming in detergent. e.g. alkyl monoethanolamide
  7. builder: enhance the cleaning efficiency of detergent by softening the water. e.g. sodium tripolyphosphate
*sodium tripolyphosphate is banned as when it is discharged into lakes, will cause euthrophication.
Normally a box of detergent contains between 15 - 20% of detergent.

Colourful Transition Elements














"Wow!!"

"They're so beautiful!"
Comments by my students when I showed them those colourful chemical in the test tubes.

From the left, it was iron(III) chloride, iron(II) sulphate, copper(II) sulphate, potassium dichromate(VI) and potassium manganate(VII).

Silicon Valley

"A place where silicon is mostly found?

"A place in Malaysia?"
As I discussed about the uses of semi-metal in the microelectronic industries, I asked my students where is Silicon Valley. Above are some examples of responses I get.
Ha ha.. Silicon Valley is at the sounthern part of San Francisco, US. It originally referred to the large number of silicon chip innovators, semi-conductors and computer industries in this area. However, now it refers to the region where most of the leading ICT-based company reside. Companies like Microsoft, HP, Apple, Intel, eBay, Yahoo, Google are headquartered here.
Can we imagine, what would happen to our world without silicon? A world without handphone, ipod, mp3, computer, etc.. out of imagination... My students get stunned when the ideas sank into their deep heart...

Stanford University and its graduates play an important roles towards the development of this area.


Picture taken at Stanford Universtity, San Francisco during my visit during Christmas year 2003.

2009-06-20

All About Moles

Let's start a journey of the mole....
















Any relationship with the mole with the Avogadro Constant, Mass and Volume of Gases?



Five Short Chapters


I
I walk down the street.
There is a deep hole in the sidewalk
I fall in.
I am lost… I am helpless.
It isn’t my fault.
It takes forever to find a way out.

II
I walk down the same street.
There is a deep hole in the sidewalk.
I pretend I don’t see it.
I fall in again.
I can’t believe I am in the same place.
But, it isn’t my fault.
It still takes a long time to get out.

III
I walk down the same street.
There is a deep hole in the sidewalk.
I see it is there.
I still fall in. It’s a habit.
My eyes are open.
I know where I am.
It is my fault. I get out immediately.

IV
I walk down the same street.
There is a deep hole in the sidewalk.
I walk around it.

V
I walk down another street.


AUTOBIOGRAPHY IN FIVE SHORT CHAPTERS
From There’s a Hole in My Sidewalk By Portia Nelson

2009-06-09

Displacement Reaction

I found these two videos on displacement reaction from youtube.com. It's quite interesting! Have a look...

video

(1) Reaction between silver nitrate solution and copper

video

(2) Reaction between copper sulphate solution and iron nail
For the first reaction, reaction between silver nitrate solution and copper
  • copper is more electropositive than silver
  • copper displace silver from its salt solution
  • the silver solid, silver is displaced by copper from its salt solution
  • Chemical equation:
     AgNO3(aq) + Cu(s) --> Ag(s) + Cu(NO)3(aq)
Question: Why does the colourless solution turns blue?
For the second reaction, reaction between copper sulphate solution and iron nail
  • iron is more electropositive than copper
  • iron displace copper from its salt solution
  • the brown solid, copper is displaced by iron from its salt solution
  • Chemical equation: 
      CuSO4(aq) + Fe(s) --> FeSO4(aq) + Cu(s)
Question: Why the intensity of blue copper sulphate solution decrease?
Points to ponder: Why both reaction are examples of redox reaction?

Food Additives in Chili Sauce

Let's try to look at the ingredients in this chili sauce pack?
Besides the main ingredient: Chili, to give a good taste of chili.
of course! Why there are so many other things being added here?
  • permitted food conditioners(modified food starch, Xanthan Gum)
  • permitted preservative(sodium benzoate)
There are known as Food Additives!
Food additives are added into food in small quantity to
  • make food last longer
  • enhance the flavour of food
  • improve food appearance

Can you identify more examples of food additives in some food packages at your homes? Do these food additives bring any harm to human if being consumed in large amount? Looking forward comments on this topic...

2009-06-07

Scoring 1A in SPM Chemistry

Guess scoring 1A in SPM Chemistry is everyone hope. ..

Here is a story from a student, Chong. She said her practice and experience in great details.

http://www.malaysia-students.com/2006/06/scoring-1a-in-spm-chemistry.html

You're welcomed to post your comments after reading the article...

2009-06-05

Heating Curve


The graph shows the heating curve of element Y.
Describe the graph in terms of state of matter, particle arrangements and changes in energy.

From t0 – t1


1 In liquid state


2 Particles are arranged closed to each other but not closely packed together


3 Particles are not arranged in order


4 Energy increases



From t1 – t2


5 In liquid and gas state


6 Some particles are close to each but some are far apart


7 Particles are not arranged in order


8 Energy remains constant//does not increase



From t2 – t3


9 In gas state


10 particles are far apart from each other


11 Particles are not arranged in order


12 Energy increase

2009-06-04

Iron ore in Hainan, China

Iron ore from Hainan, China

Haian is an island at the southern part of China. It was occupied by Japanese in 1939 during Second World World. Its iron ore deposits was greatly exploited by Japanese. Tones and tones of iron ores were sent to Japan.


Iron powder that is extracted from its iron ore.


Pictures taken when I visited Hainan with my parents in year 2008.

Some chemicals I saw during my holiday trip

This is calcium sulphate that I found out in one of the museum when I visited California in year 2003. Calcium sulphate is white in color, an ionic compound that exists in the form of crystal.

This is sulphur... in the form of yellow crystal.

Pure Metal vs Alloy

1) What are some examples of pure metal?

~ Aluminium, copper, gold, silver.

2) How about atom arrangement for pure metal?




3) What happened to the metal when force is applied?E.g. when a metal is knocked, or pulled?



When force is applied, layers of atoms in pure metal slide.

So, metals are ductile.



There are empty space between the atoms. When it is knocked, the shape of the metal changes.

So, metals are malleable.

4) What are properties of pure metals? Can we just name two of them.

Now, let's look at atom arrangement in alloys.



5) What is alloy?

It is a mixture of two or more elements with a certain fixed composition in which the major component is a metal.

Now, Try to imagine when an alloy is knocked. When a force is applied to an alloy?What happened to its layers of atoms? What is the role of the foreign atoms?


6) Why alloy is harder? more malleable and ductile than its pure metals?
Perhaps now your have a better answer.