Saturday 25 June 2011

Be careful, Fake eggs!!

Last week, when I opened an egg, I realized that the egg was watery and after it was fried, it did not taste as good as before. I was wondering that time, was it a real egg? To check out the truth, I have done some searching.

It is unbelievable that fake eggs is a common manner in China!! Many people invented fake things to earn money as fast as possible. Based on my research, fake egg's shell is made from calcium carbonate. "Egg yolk" and "egg white" are made of sodium alginate, alum, gelatin, eatable calcium chloride, lactone, benzoic acid, water, and food colouring. To make an "egg white", sodium alginate is dissolved in warm water and mix with gelatin and benzoic acid, alum, and other chemicals. Mix them into egg white like shape. "Egg yolk" is just adding the lemon yellow food colouring and then pour into a mold which has egg yolk like shape. After that, put "egg yolk" into calcium chloride water to let the "egg yolk" appears to have a thin layer of membrane. This membrane formed around the "egg yolk" is to stabilize the shape. Transfer the "egg yolk" and "egg white" into a plastic mold and soak into the liquid of calcium chloride to stabilize the shape. "Egg shell" is made of paraffin wax, gypsum powder and calcium carbonate. Melt the paraffin wax and mix with gypsum powder and calcium carbonate; surrounding the "whole egg" with the mixture of paraffin wax, gypsum powder and calcium carbonate, then leave it cool and dry. A artificial egg is completed!

The materials used to make a artificial egg are all chemicals. These chemicals have side effects to our body if consume it. Lactone which acts as a solidifier of the "egg yolk" and "egg white" can cause metabolism disorder. Benzoic acid which used as preservative can be harmful to our brain and nervous system and may cause liver disease and Alzheimer's disease. Calcium chloride which formed the thin membrane to stabilize the shape and alum which function as softener may cause nerve and liver disease. They may also affect the ability to produce blood. Therefore, if we consume too much artificial egg for a long time, we will suffer from diseases.

Although artificial eggs are similar with genuine eggs, we still can identify which is fake and which is genuine. However, it is hard for us to identify those traits. Below are the features of a fake egg:
1.  After opening the egg, fake "egg white" and "egg yolk" will soon mix together. This is because the "egg yolk" and "egg white" are made of the same raw materials.
2.  Fake egg's shell is a little shinier than the real one, but it is not very noticeable.
3.  When touch the fake egg by hand, it feels a little rougher than the real egg.
4.  Real egg smells a little like raw meat.
5.  When tap the egg lightly, real egg makes a more crispy sound than the fake egg.
6.  When frying a fake egg, the yolk will spread without being touched.
7.  Fake eggs are larger than real eggs.
Experts warn residents of the danger of eating fake eggs. Not only they do not contain any nutrients, a long term consumption of alum could cause dementia. This is a very serious manner. Thus, we need to beware of these fake eggs.

Friday 10 June 2011

Rusting: Oh my god, my nail become brown colour.

Rusting occur everywhere in our daily life. Only metals will rust.For example,iron nail,car and iron gate. The products is Fe2O3 . x H2O  which is brown colour.This oxidation process known as corrosion of the metals.

Rusting will occur that must have these all of the two conditions which are oxygen and water. The process of rusting needs an anode and cathode in different places on the surface of an iron piece. Oxidation half-reaction occur in anode.

Anode: 2Fe (s) → Fe2+ (aq)    + 4e-

The four electrons from anode move to cathode. Reduction take place in cathode .Oxygen dissolved in water is reduced to become water in cathode.

Cathode: O2 (g) + 4H+ (aq) + 4e-→2H2O (l)

When combine half-equation in anode and cathode,overall oxidation-reduction is:

2Fe (s) + O2 (g) + 4H+ (aq)2Fe2+ (aq) +   2H2O (l)

Fe2+ ions move out of the cathode then,it oxidizes to Fe3+ and contact with dissolved oxygen to form rust.

4 Fe2+ (aq)    + O2 (g) + 4H2O (l) → 2Fe2O3 . x H2O(s) + 8H+ (aq)

Rusting will occur faster when there are acid and salt presences. 3 ways can reduce rusting which is
using protective coating, alloying and sacrificial protection. Protective coating is to prevent air and
water reaching in the surface of iron. We can use oil and grease for moving part of engine. Paint also
can use for the objects which are not easily to scratch such as gates and car. Then, plastic can use for
light item such as clothes hanger and wire fences. Besides that, alloying iron to stainless steel also
prevent rusting. Stainless steel is composed of chromium, carbon, iron and nickel. The chromium and
nickel provide a protective oxide coating so firming bonded to iron and no easily to remove. Other
way is sacrificial protection that is using more electropositive metal as sacrificial metal attached to
iron. This can explain by the more electropositive metal will act as anode which is oxidation occur site
protect less electropositive metal rusting. For example, iron attach to magnesium. Magnesium more
electropositive than iron because magnesium more tendency to lose electron.