August Reflections

This month we started to learn on sexual reproduction in humans. I feel that this topic is a little more difficult than other topics because there are many names to memorise. However, this topic is quite interesting because it is not exactly the usual type of lesson we have normally, and also there is no practical on this lesson. It allows us to deeper understand what is happening in our body including puberty and also how we are formed.

Also, Term 3 test results that I had got back were good, because I got 35.5 marks!

Shao Xuan

(Post #13)

July Reflections

We have started on ecology. Personally I do not like biology and ecology but we still have to learn all 3 sciences while in Sec 2. When in primary school, I did not know the reason why food webs were so small and why food chains were so short, but now I know that the answer is that the energy is lost when it is passed through the animal. I had also learnt about the carbon cycle and how carbon is passed on through various states to ensure a continuous cycle. The test is coming up soon and I hope to score well.

Shao Xuan

(Post #12)

May Reflections

The test was considerably easy and I managed to get an A1 (33 marks). There was a topic on converging lenses, which I thought was quite difficult at the start because there were a lot of ray diagram drawing, and also there were many types of images produced when the focal length changed. Also I was not very sure that I was supposed to do the online lesson on colours, but when I found it I did it quickly. I had always thought that the primary colours were red, yellow and blue and not cyan, magenta and yellow instead. I look forward to the Science lessons in Term 3.

Shao Xuan

(Post #11)

April Reflections

In this month I went again for another Science for Fun. As always it was interesting with new experiments and so. This month we were introduced to reflection and refraction. At first I was kind of confusing, the convex and concave mirrors, but now I am starting to get it, and how the images come out inverted, or upright, or virtual or real and so on, and now there is refraction to worry about. It is more difficult than reflection because there are different bodies of matter the light rays pass through with different refractive index and so comes out the fake images and the real thing itself. I once mixed up the lines on whether it should be dotted or straight. I need to continue to study this topic to understand more on refraction. Though it is not tested, I still think I should know this topic. And the test is on 5th May which is coming very soon, and I must start to study...

Shao Xuan

(Post #10)

Science Enrichment 2

Different Types of Fertilisers

Fertilisers are very important for the growth of plants. They provide them with nitrogen which gets converted into useful forms either for the plant itself of on the soil for other plants to use. Each plant requires different properties from the fertilisers and so it is very important for farmers to pick the right fertilisers for farming.

Acidic, fertilisers are made up of usually primary and secondary macronutrients. There are 3 primary macronutrients: nitrogen, phosphorous and potassium. The secondary macronutrients are calcium, sulfur and magnesium. One each from two types of macronutrients is usually combined together along with some other micronutrients like boron, chlorine, manganese, iron or zinc.

Rock Phosphate

Rock phosphate, basically PO₃, is actually the 20-million-year-old remnants from the remains of aquatic and land critters. It is in the form of clay, and will not leach out of the soil but be absorbed by roots of the plant. It releases the 30% of phosphorus at a very slow rate and can last for up to 5 years. It is often mixed together with other fertilisers and it can attract roots to the area spread with the fertiliser.

Ammonium Nitrate

Ammonium nitrate is made by combining nitric acid and ammonia. This reaction is very violent though many do not know it. Ammonium nitrate is made up of 27% nitrogen and is usually available in granule form. This is the most popular form of fertiliser because it does not affect the pH of the soil much. It constantly provides a large amount of nitrogen to the plants. However some there are some reservations on this type of fertiliser because it explodes and can be fatal.

Superphosphate

Superphosphate came about from tricalcium phosphate where the latter was too insoluble to form a fertiliser. It is thus reduced to monocalcium phosphate and added to sulfuric acid to form the superphosphate of lime. Superphosphate is usually used in the early stages of gardening. It is very concentrated and should be mixed to other fertilisers because the plants would die if not.

Potassium Chloride/Potassium Sulfate

Also known as the muriate of potash and the sulfate of potash respectively, potassium-based fertilisers are used only when there is a potassium deficiency in the soil. It is applied commonly when sowing. Potassium chloride is the most common potassium-based fertiliser and is also the cheapest. However, if such fertilisers are used in soil where there is an abundance of potassium, it can cause diseases such as root rot. Thus it is applied in small amounts unless there is no potassium in the soil.

Shao Xuan
(Post #9)

Science Enrichment 1

Elements

10 Random Elements

The periodic table is made up of 118 elements so far, but in this list there are 10 random elements picked for reference. Enjoy!!!

1. Chlorine (Symbol “Cl”, Atomic number #17, Atomic mass 35.453)

Uses: Chlorine bombs, organic chlorine compounds, bromine extraction

2. Copper (Symbol “Cu”, Atomic number #29, Atomic mass 63.546)

Uses: Electronics, wires, architecture, alloys

3. Krypton (Symbol “Kr”, Atomic number #36, Atomic mass 83.798)

Uses: Photography, florescent lamps, krypton fluoride laser

4. Iron (Symbol “Fe”, Atomic number #26, Atomic mass 55.845)

Uses: Metal compounds, food and health, blood

5. Gold (Symbol “Au”, Atomic number #79, Atomic mass 196.967)

Uses: Money, jewelry, tooth crowns, electronics

6. Sodium (Symbol “Na”, Atomic number #11, Atomic mass 22.990)

Uses: Alloys, nuclear reactor cooling, transfer heat

7. Aluminium (Symbol “Al”, Atomic number #13, Atomic mass 26.982)

Uses: Packaging, construction, household appliances, alloys

8. Nitrogen (Symbol “N”, Atomic number #7, Atomic mass 14.007)

Uses: Stainless steel, disable explosive liquids, electric parts

9. Cobalt (Symbol “Co”, Atomic number #27, Atomic mass 58.933)

Uses: Alloys, pigments and colourings, batteries

10. Titanium (Symbol “Ti”, Atomic number #22, Atomic mass 47.867)

Uses: Aerospace and marine, architecture, pigment

Shao Xuan
(Post #8)

Science for Fun Reflections

Science for Fun Reflections

The third time I participated in this activity, I could remember, there were around 1 or 2 experiments that were repeated if I remember correctly. But the others were new and interesting enough to make me go back for a fourth session. I like the way on how the organizers actually provide us with enough apparatus and chemicals for us to try repeatedly even if we failed in the first try. Also it was nice to carry out the experiments at our own speed as some of us liked to rush through or go slow. For me, I preferred going fast because after I observed the results there was nothing much to see anymore, unless I had to try again.

MOVING AIR AROUND
I had heard of this hair-dryer-ping-pong-ball experiment, but never really tried it before because when I had a ping pong ball I didn’t have a hair dryer and vice versa. Well when this time I tried it, it worked perfectly fine. Apparently due to Bernoulli’s principle the faster speed caused by the moving air created a lower pressure which prevented the ball from being flung away out of the air stream. That is the same principle used in aircraft to create lift and also for propeller planes.

HUMAN BATTERY
Before this experiment I knew that our body conducts electricity, well that is how we get electrical shocks when we touch power sockets or some electrical source. But I didn’t know why there was this copper and aluminium plates for us to put our hands on. I think it has something to do with the polarity of the batteries or something like that. I felt a tingling sensation then because of the current flowing through my hands.

EYE MODEL
The experiment simulated what happens in our eye. There was the water which symbolized the vitreous humour and the white plate and lenses that represented the optical disc and the retina. So I learnt that the image was inverted in many types of ways because of the various lenses we use to correct short-and-long-sightedness.

TORNADO TUBE
Probably the most fun experiment there, it simulated vortices which look like tornadoes in the bottle. It was fun to see the liquid flow down and when I stopped the vortex the air was unable to rise up and the liquid stopped flowing down. Apparently some of Bernoulli principal was used in the experiment because of the difference in air pressure at the base and at the top of the vortex.

TOP SECRET
This felt like a weird experiment because I couldn’t seem to get it right. Every time I spun the top, it would like go off course and spin off onto the table. Thus I had to just watch others spin it and observe. I think the experiment has to do with some electromagnets and polarity and it repels the top to the end of the cone when spun. The top probably became a magnet when spun.

PINEAPPLE GELATIN
This was an experiment that was repeated. The last time I had problems measuring the 2ml of the pineapples because the pineapple stuck to the dropper, making it very difficult to see the 2ml mark and even worse, most of the droppers were broken at the top losing all the pressure and making it useless. Thus I had wrong and different results as compared to the previous experiments.

LAVA LAMP
I didn’t know lava lamps worked that way, because they would probably use up all the Alka-Seltzer tablets after 5 minutes or something. This experiment was very interesting as it was very beautiful to look at, and it shows how air can carry the water to a lesser dense liquid like oil, then dropping back to the bottom when the air bubble is released into the air.

BLUE BOTTLE
This experiment was a bit confusing because the chemicals used were new to me, like methylene blue solution. Anyway, I learnt that solutions will change colour when vigorously mixed with oxygen. It is quite amazing on how the solution changes colour when we shake it and return to normal when the oxygen is released back.

ADSORPTION OF HEAVY METAL IONS
I went to check adsorption when I went home and adsorption is when a solid or liquid sticks to a surface. So I’m guessing that the copper (II) had been adsorbed onto the orange peel and thus the lesser amount of copper (II) in the readings after. I didn’t know that there was a machine to measure copper (II) and the concentrations of other materials until I saw it. It was quite complicated and sophisticated.

Overall, I had enjoyed my time in the lab doing experiments and I hope to go for future science for fun sessions to carry out experiments.

Shao Xuan

(Post #7)