DNA Molecules

DNA stands for deoxyribonucleic acid.  It is an important molecules that carry genetic information for living organisms. The molecule forms double helix structure. 

Picture Source : Wikipedia

DNA is a polymer that made up of the smaller repeating units, called nucleotides. 

Some fun facts about DNA(from 10 Interesting DNA Facts

Fun, Useful, and Interesting Facts about DNA, By Anne Marie Helmenstine, Ph.D., About.com Guidez)

1. If you put all the DNA molecules in your body end to end, the DNA would reach from the Earth to the Sun and back over 600 times (100 trillion times six feet divided by 92 million miles).
2. A parent and child share 99.5% of the same DNA.

Knowledge about DNA  is widely used in the following fields : 

1. DNA profiling
2. Genetic engineering
3. History and anthopology
4. Bioinformatics
5. DNA nanotechnology. 

Isomers of Propanol

Propan-1-ol

                                                                         Propan-2-ol


Isomerism in Alcohols due to two reasons :

1. Position of its functional group, -OH group
2. Branching of carbon chains

How does temperature affect eggs?

Do you like eggs? Half-boiled, fried egg, etc....
Have you ever pondered these questions?

1. Do different temperature affect the texture of eggs?
2. Does the size of eggs affect the cooking of eggs?

I thought cooking eggs just a simple thing for every lay man like me.  I was surprised to find that a branch of food science, called Molecular Gastronomy investigate all these. 

Source : DouglasBaldwin.com

The picture shown eggs cooked in a water bath for 75 minutes at temperature from (57.8 ⁰C to 66.7 ⁰C) by Douglas Baldwin.

In Khymos's blog, Towards the perfect soft boiled egg, I even found a formula relating temperature of water,  mass of eggs & cooking time.

Amazing?

According Wikipedia, Molecular Gastronomy is a sub-discipline of food science that seeks to investigate, explain and make practical use of the physical and chemical transformations of ingredients that occur while cooking, as well as the social, artistic and technical components of culinary and gastronomic phenomena in general.

First Landfill Gas Power Plant

First Landfill Gas Power Plant in Air Hitam Sanitary Landfill, Puchong, Selangor . The park was recognized as first Electrical New Energy Power Plant which uses landfill gas in Malaysia Book of Records.

The power plant generates 2.0 Megawatt electricity supply by trapping and burning a by-product of of decaying waste - Methane gas.

Based on newspaper report, Air Hitam Sanitary Site has received solid wastes collected from Klang Valley since 1995 for 11 years. The site was ordered to closed by the state due to new housing area nearby.

Landfill gas produced from chemical reactions and microbe actions upon the solid wastes.  Methane gas is one of the main composition in the landfill gas produced.  The gas collected through system of pipes & well are then burned to carbon dioxide, water & heat.

"It is estimated that that there is here is enough gas here to power the generator to provide about 15 years of electricity to about 2,000 households", Worldwide Holdings chairman Datuk Mohd Arif Abd Rahman said.

For further reading, please click

• Landfill gas - energy project
• New source of power at landfill from The Star Dec 28 2004
• Building paradise from a waste land May 4 2009

Chloroform

Trichloromethane or known as chloroform, CHCl₃ is one of the product of substitution of methane with chlorine(chlorination) in the presence of UV sunlight.  The output of this process is a mixture of chloromethane, dichloromethane, trichloromethane & tetrachloromethane).

The following are the chemical equations that show the step by step reactions in substitution reaction.

CH₄ + Cl₂ → CH₃Cl + HCl

CH₃Cl + Cl₂ → CH₂Cl₂ + HCl

CH₂Cl₂ + Cl₂ → CHCl₃ + HCl

CHCl₃ + Cl₂ → CCl₄ + HCl

Uses of chloroform

• a common solvent
• was once a widely used anesthetic(Its vapour easily depress the central nervous system)

Determine the Physical State of A Substance at a Given Temperature

SPM 2012 Paper 1 Question 25  

1. The melting point and boiling point of  V and W are lower than 100⁰C. Both exist as solid at 100⁰C. 
2. The melting point of  X is lower than 100⁰C. The boiling point of X is higher than 100⁰C.  It exists as liquid in room temperature.
3. Both the melting point and boiling point of Y are lower than 100⁰C.  It exists as gas in room 100⁰C. 

The correct answer is : C

Avogadro Constant & Amedeo Avogadro

Avogadro Constant : 

(Definition : Number of particles in 1 mole of a substance )

is named after

 Amedeo Carlo Avogadro(1776 - 1856)

for his great contribution towards chemistry.

The Meaning of Relative Atomic Mass

What is the meaning of Relative Atomic Mass of an element?

A carbon-12 atom is chosen as a reference. Carbon-12 is assigned a mass of exactly 12 unit.
Mass of an atom of an element when compared with 1/12 of mass of a carbon-12 atom.