Electrolysis

Electrolysis is the chemical processin which the dcomposition of ionic compounds is dne by passing electricity through molten compounds or aqueous solutions of compounds. It can be used to cover a metal surface with another metal by electroplating, the purification of copper, the extraction of reactive metals such as aluminium, an dthe manufacturing of chemicals such as sodium chlorine and bleach. The apparatus used for electrolysis is called an electrolytic cell. It consists of two electrodes in aliquid electrolyte. A direct current power source is connectd to the electrolytes, decomposing it to simpler substance.

The seperation of substances using electrolysis is also possible. One example would be extracting sodium sodium chloride. Sodium choride is an ionic compound consisting of sodium ions and chloride ions, In the solid state, the oppositely charged ions attract each other and thus are not free to move, but in teh molten state, the ions are free to move. When a current is passed through the molten sodium chloride, a silvery liquid forms at the cathode(negetive electrode), this is molten sodium. Bubbles of a yellow-green gass appear aroung the anode(positive electrode, the gas chlorine. This happens as the ions are attracted to the oppositely charged electrode instead of each other, and hence a sample of sodium is extracted.

Term 3 reflection

In term 3, I learnt about seperation techniques more in depth than during the e-learning. It was pretty easy, now that I was more familiar about the properties of various subtances. After that, we learnt about the animal and plant cells. Personally, I think that this is not much of a challenge for me, as I had read up more detailed information about cells in primary school, and this was like revision for me. However, I cannot really memorise the functions of the cells properly, I guess this is because there are many different parts on a cell. So far, I have seen that topics related to biology are not really the kind of subject that I can memorise the content very well, and have to spend more time on it. I think I will have to work on that, and make myself good at all topics, and not just a select few.

Term 2 reflection

At the start of the term, we were introduced to the Kinetic Particle Theory. I particularly enjoyed myself when we were shown the Eureka video on the topic, as it was very interesting, and a little humourous. After that, we learnt about elements, mixtures and compounds. I feel that this was the most difficult part of the term for me, as I could not really remember the properties of mixtures and compounds properly, and I also mixed up the symbols  of elements. However, after a few weeks of learning this, I became more familiar with the topic, and began to do the assignments with ease. I did pretty well for the test, but not as well as I did in term 1. I think that e learning for seperation techniques was quite good, and it helped me refresh my memories about the properties of mixtures and compounds.

Term 1 reflection

For term 1, we basically learnt about the measurements, usage and names of various apparatus in the lab, and the various SI units used. I feel that the things taught this term were relatively simple, but also very important too. i believe that I have done pretty well in this term, as I have done quite well for the assignments and the test too. Towards the end of the term, we learnt about density, and how to calculate it. I think that this was the more challenging part of the term for me, as I am quite careless when it comes to calculations, and my carelessness caused me to answer some questions wrongly in assignments. I think that term 1 was only a warm up for the terms up ahead, and I am sure that I will have to work harder in the upcoming terms to maintain my standard in class.

Review of discovery in science: Discovery of earth-like planets (video)

Gist of talk:
Astronomer Dimitar Sasselov and his colleagues search for Earth-like planets that may, someday, help us answer centuries-old questions about the origin and existence of biological life elsewhere (and on Earth). Preliminary results show that they have found 706 "candidates" -- some of which further research may prove to be planets with Earth-like geochemical characteristics.

Source: http://www.ted.com/talks/dimitar_sasselov_how_we_found_hundreds_of_potential_earth_like_planets.html 

My review:
The talk is basically about the results of the man, Dimitar Sasselov, and his collegues' research with a telescope that uses the transit method to discover planets and infer their composition. Their research is a very meaningful one, as it has resulted in the discovery of many Earth-like planets, and possibly one of those planets is able to support life. His research has given us a new perspective to life as we know it, whether the biochemistry on Earth is universal, and happens on all life-sustaining planets. They found out that a membrane similar to a cell membrane is formed on the surface of bubbles which form naturally when there are small puddles of water. On a whole, the talk is very informative and helps us to get a better understanding of the universe, and life as we know it.

Review of discovery in science: Better way to grow stem cells developed

Better Way to Grow Stem Cells Developed

ScienceDaily (Aug. 23, 2010) — Human pluripotent stem cells, which can become any other kind of body cell, hold great potential to treat a wide range of ailments, including Parkinson's disease, multiple sclerosis and spinal cord injuries. However, scientists who work with such cells have had trouble growing large enough quantities to perform experiments -- in particular, to be used in human studies. Furthermore, most materials now used to grow human stem cells include cells or proteins that come from mice embryos, which help stimulate stem-cell growth but would likely cause an immune reaction if injected into a human patient.

To overcome those issues, MIT chemical engineers, materials scientists and biologists have devised a synthetic surface that includes no foreign animal material and allows stem cells to stay alive and continue reproducing themselves for at least three months. It's also the first synthetic material that allows single cells to form colonies of identical cells, which is necessary to identify cells with desired traits and has been difficult to achieve with existing materials.
The research team, led by Professors Robert Langer, Rudolf Jaenisch and Daniel G. Anderson, describes the new material in the Aug. 22 issue of Nature Materials. First authors of the paper are postdoctoral associates Ying Mei and Krishanu Saha.
Human stem cells can come from two sources -- embryonic cells or body cells that have been reprogrammed to an immature state. That state, known as pluripotency, allows the cells to develop into any kind of specialized body cells.
It also allows the possibility of treating nearly any kind of disease that involves injuries to cells. Scientists could grow new neurons for patients with spinal cord injuries, for example, or new insulin-producing cells for people with type 1 diabetes.
To engineer such treatments, scientists would need to be able to grow stem cells in the lab for an extended period of time, manipulate their genes, and grow colonies of identical cells after they have been genetically modified. Current growth surfaces, consisting of a plastic dish coated with a layer of gelatin and then a layer of mouse cells or proteins, are notoriously inefficient, says Saha, who works in Jaenisch's lab at the Whitehead Institute for Biomedical Research.
"For therapeutics, you need millions and millions of cells," says Saha. "If we can make it easier for the cells to divide and grow, that will really help to get the number of cells you need to do all of the disease studies that people are excited about."
Previous studies had suggested that several chemical and physical properties of surfaces -- including roughness, stiffness and affinity for water -- might play a role in stem-cell growth. The researchers created about 500 polymers (long chains of repeating molecules) that varied in those traits, grew stem cells on them and analyzed each polymer's performance. After correlating surface characteristics with performance, they found that there was an optimal range of surface hydrophobicity (water-repelling behavior), but varying roughness and stiffness did not have much effect on cell growth.
They also adjusted the composition of the materials, including proteins embedded in the polymer. They found that the best polymers contained a high percentage of acrylates, a common ingredient in plastics, and were coated with a protein called vitronectin, which encourages cells to attach to surfaces.
Using their best-performing material, the researchers got stem cells (both embryonic and induced pluripotent) to continue growing and dividing for up to three months. They were also able to generate large quantities of cells -- in the millions.
The MIT researchers hope to refine their knowledge to help them build materials suited to other types of cells, says Anderson, from the MIT Department of Chemical Engineering, the Harvard-MIT Division of Health Sciences and Technology, and the David H. Koch Institute for Integrative Cancer Research. "We want to better understand the interactions between the cell, the surface and the proteins, and define more clearly what it takes to get the cells to grow," he says.
Other MIT authors of the paper are Said Bogatyrev, Z. Ilke Kalcioglu, Maisam Mitalipova, Neena Pyzocha, Fredrick Rojas and Krystyn Van Vliet. Jing Yang, Andrew Hook, Martyn Davies and Morgan Alexander of the University of Nottingham (United Kingdom) and Seung-Woo Cho of Yonsei University (Korea) are also authors of the paper.

Source: http://www.sciencedaily.com/releases/2010/08/100822150643.htm (thanks to Mr Tan Kai Yuan for posting this on facebook)

 My review:
I feel that this discovery will be beneficial to many people around the world. With the development of a new method to grow more stem cells, more research can be conducted, and hopefully more ways to treat people using stem cell treatment, possibly improving the methods we use today to treat infertility, diabeties, etc. Also, more people will be able to have the option of going through stem cell treatment without going overseas, and this will definitely save more lives, since stem cell treatment can be used to treat nearly any kind of disease that involves injury to cells as stem cells can transform into any specialised type of cell in the organism. I believe that the surface created for the production of stem cells, can also be put to good use, possibly using it to allow other cells to reproduce on it. I think that the researchers have done a very good job at creating this surface, and I think that it will not be long before another breakthrough in stem cell therapy will be discovered, with the improvements in the production research materials now.

Term 3 test reflection

The term 3 test was tested on elements, compounds and mixtures, solutions and supensions, and seperation techniques. I scored 31 for this test. I feel that I have not been very focused for science, as there is a downward trend in my science test results. Although I got an A1 this time, I am not very satisfied with my results, as this is only a borderline A1, and I could drop to A2 anytime.

I think that my biggest shortcoming for this test is that I made many careless mistakes and mixed up the properties of certain things. To improve on this, I will read up more on the topics, and make sure that I can remember the many properties well. This will also be combined with doing more revision papers and worksheets to solve the problem of making many careless mistakes, which has been bugging me since primary 5. I know that if I put my heart and mind to achieve the above stated, I am sure that the next test I do, will be one that I score a strong A1.

Also, I hope that I can get exemption for science, since I have gotten A1s in the past few terms.

Term 2 test reflection

The term 2 test was on measurements and matter, and I scored 34.5. I did not improve from the last test, but instead deproved by 2 marks. But still, I am still quite satisfied with my marhks, and so do my parents, as I still got an A1. I feel that the test was reletively easy, but I need to work on reading the questions more carefully. Also, I think that I have to spend more time memorising the prefixes for the measurements, as I still cannot remember them very well, and had to spend a lot of time trying to recall them for the prefix section of the paper. On a whole, I think that I am still ding great for the year, and hopfully I can get an A1 again for the next test.

Term 1 test reflection

This test was quite simple, and I got 36.5 marks. All that I needed to do was to pay attention in class and do a little revision at home. I think that this is a very good start for the year, and I hope that I can kep up the good work for the other terms. I feel that my achievement of 36.5 should be credited to Ms Leong. Without her teaching me well, I would not have been able to get such high marks.

My parents were very satisfied with the marks that I got (obviously, since I got an A1). I should do better for the next test to impress them even more.

Science ace: Why ice floats on water?

Normally, for liquids, when they freeze, they become more dense. However, when water freezes, it becomes less dense. Why is that?

A water molecule is composed of two hydrogen atoms (H) and one oxygen atom (O). The atoms of hydrogen and oxygen are bound by sharing their electrons with one another. This bond is called a “covalent bond”.

However, since oxygen atoms pull electrons more strongly than hydrogen atoms, the oxygen atom in a water molecule has a slightly negative charge and the hydrogen atoms have a slightly positive charge. So adjacent water molecules are attracted to one anotherthrough the slightly negatively charged oxygen atoms and the slightlypositively charged hydrogen atoms. This interaction is called “hydrogen bonding”. Hydrogen bonding is much weaker than covalent bonding, however, this type of bonding has a large total effect because there are so many hydrogen bonds.

When the temperature of water goes below 4 degrees celsius, which is the temperature where water attains maximum density, the hydrogen bonds cause the water molecules to b held in 3D crystals, leaving many holes in between them. This structure is formed by the expansion of the water molecules as the temprature drops below 4 degrees celsius. The holes increase the ice's volume, but does not really increase the mass of ice, hence the ice's density drops lower than that of water. Since something of lesser density floats on something of higher density, ice then floats on water.

Reflection for trip to science metrology center.

A couple of days ago, I went to the Science Metrology Center with some other schoolmates. We learnt more about SI units there, how they are calculated and recorded. For certain masses, there is a "ideal" mesurement for it, and it is in the form of a weight. These weights are the so called "correct" measurements for mass, and are kept in some laboratory in France. They were originally used for comparison with other masses on a beam balance. Many countries in the world have a replica of that weight.

Also, I also saw how they measure the speed of light. There would be a laser generated, and there are also many mirrors in the machine too, reflecting the light into a hole of some sort. The machine would then digest the information, and then churn out the results.

For time, they use a caesium atomic clock that almost occupies a whole room! Accordding to the personnel, the clock is very accurate and only loses asecond in about a million years!! I do not think that any of our watches will be able to reach such an accuracy.

During the tour, we also saw a very interesting room, the comdom test lab. According to the personnel there, an electrical current is passed through the comdom, and if the current flows smoothly through the comdom, it shows that the comdom has passeed. Honestly, I do not know how a current flowing through a comdom, shows that it is qualified for use.

In all, I think that this trip to the Science Metrology Center has been very meaningful. I have learnt more about the SI units and how to measure them. I am sure that this trip has given me a better understanding of the SI units and this will definitely be helpful for me to answer questions related to SI units. I feel that the school should not only allow a small group of students to go, but possibly let more students go, in different batchees maybe. I think that it has been a great loss for those who have not went there.

Why an egg sinks in tap water but floats in salt water

Q: Why and how did the density of water change when salt was added to it?

Ans: The water became more dense after the salt was added, as more of the mass of the water increased, compared to the volume of the water increased, when the salt is added. The formula for calculating density is mass/volume, hence when the mass increases more than the volume does, the density increases. Therefore, the water became denser when salt was added to it.

Q: Why the egg sunk in tap water but floated in salt water.

Ans: Naturally, the egg is denser than normal tap water. However, when salt is added to the water, it becomes denser than the egg, due to the reasons stated above. Since a less dense substance or objects floats on top a denser one, the egg now floats on the denser salt water.