Wall Mural

I have never been asked to do a wall mural before. Initially I thought it will be quite difficult to get student to provide ideas on what to draw on the wall. However I was quite shocked that the students are very proactive, they drew their basic concept on a paper and then get approval from us before drawing on the wall.

Initially the sketching is quite badly done, however once they start to paint on it, we can slowly imagine the picture they are going to put up.

Each wall is done by around 8-10 students within 2-3 days (each day 3 hrs only). I am really impress with their drawing . See my pictures, maybe you will like them too. If you wish to draw on the wall of your house, maybe you can get paint from me as I still have some left over paint.

My Ant Universe (continued)

Hi is so long that I have not update my blog on my ant universe. Actually my ants have died long ago. I think they can only survive for 2 weeks, slowly their movement become slower and died. This is the final master piece of my ants universe that is created by the ants I caught.

My Ant Universe

I saw this Ant Universe online and was interested to buy it and rear ants. It is a plastic flat aquarium with blue colour gel. To my surprize, I actually saw it at the souvenir shop in Science Centre and it cost SGD 30. So I quickly bought it to create my own ant universe.

Catching ants is a challenge as you need to be fast to keep it in a small container. However putting the ants in the aquarium is even more challenging, as once you put 1 in another will escape. So I decided to put a clear plastic tube as a passageway for the ants to travel in. At least with that, it slow down the ants from inside to escape as it needs time to travel through the passage way and before they can move to the exit we have already closed the exit.

So have a look at the aquarium at Day 1 when we just put in the ants (you can see the passageway is still there, as some ants still stay in the passageway so I cannot remove it till Day 3 when the ants are all in the aquarium.

Forgot to mention that the ant universe is not for rearing ants only, the interesting part is to see how they dig tunnel, so you can actually see my pic on Day 3 has tunnel dig by the ants already. Soon the whole aquarium will have a network of tunnels.

Day 1

Day 3

The Final Version of the Poly Density Bottle

Hi, just want to update that my student have come out with the design of the poly density bottle (with the help of their mentor). To make it interesting, they actually made 4 bottles with a theme of four season. So each bottle the colour of the plastic is link with either Spring, Summer, Autumn or Winter. Behind each bottle, the students also pasted pictures from magazine to suit its theme.

What I am proud of them is that, the group win a special mentioned prize, as the judges say it is very creative and is also look like an artistic piece that shows a science theory. Even though they are not the top 3, however the other winner are from Raffles Institute and Hwa Chong which are those top schools of Singapore, so we are really proud to win that prize.

The theory is still the same, once shake, the density of the mixture will cause 1 kind of plastic to sink another type will sink. However once the propanol and salt water is separated, the float plastic will sink to the middle and the sink plastic will float to the middle. Now have a look at their final version.

Poly Density Bottle

Another group of student who is entering the same competition are doing another experiment. Their experiment is based on the different density of the solid and liquid. We really have a difficult time to find the appropriate plastic solid that has the correct density.

In the tube shown in the video, it contain 2 solutions of different density. One is acetone which has a density of 0.81g/cm3, another is saturated salt solution (normal household salt) which has a density of 1.2g/cm3. Both solution are immiscible so they will separate when mixed.

The theory is that you can use a plastic that has a lower density and another with a higher density than the solution when mixed. Example now both solution when mixed and divide by 2, it should gives a density of 1. So if you have a plastic material density that is between 1.1 - 1.9g/cm3, it should sink when mixed. Then if you have another plastic material density that is between 0.82 - 0.99g/cm3, it should float when mixed.

So when you leave it to stand and allow these 2 solutions to separate back to their normal properties. The one with the density of 1.1-1.9g/cm3 (which is the white plastic in the video) will start to float since it is less dense than salt water. Then the one with the density of 0.82-0.99g/cm3 (the green plastic in the video) will start to sink since it is denser than acetone but less dense than salt water. Then the plastic that has a density of around 1g/cm3 (the blue solid) will float in between when mixed.

End up what you can observed is the green plastic float when the solution is mixed then sink down, the white plastic will sink when mixed and then float up. The blue plastic will remain in the middle.

Honestly, I am not sure what kind of plastic I am using but I can let you know where my material come from. The green one is from the seal of a chemical bottle, the blue one is from a mineral bottle cap and the white one is from those white colour disposable spoon (see pic).

You can try it out yourself. Actually in the link, they uses rubbing alcohol (Isopropyl alcohol). I bought a 70% isopropyl alcohol from Guardian however it is miscible with salt water so both solution cannot separate when it is mixed (same for 95% ethanol). So I do not know how the kit that they sold works. If you ever tried it before please tell me the procedure for that.

Hope you will like my sharing if you really found out that iso propyl alcohol and salt water do not separate.

The effect of the colour light on glow in the dark item

My school student was doing on a project on the effect of temperature on glow in the dark item. Initially, I gave them magnetic stirrer that come with hot plate. So one will remain in room temperature and the other one will be heated to 70 degree celsius (controlled by the hot plate).

We observe that the glow in the dark star in hot water discharge faster than the one in room temperature.

After that then I realise that the apparatus used for this Amazing Science Challenge project will be kept by the Science Centre people so we cannot give them such expensive equipment like magnetic stirrer to them. So my lab tech and I are finding ways to heat up the glow in the dark star.

Firstly we used a mug warmer, however it does not warm the water at all. So we tried to invert a beaker wrapped with aluminium foil over a light bulb which gives off heat. It indeed can heat up my water on top (which contain the star) however I realise the heat is so hot that it melts my bulb holder. Finally, we have to give up the idea using heat. Instead, we will try whether different colour light will affect the glow of the star.

We saw in the net that red colour light does not charge the particles in the glow in the dark item (you can refer to the link for info). So we compare red light with normal fluorescence light, indeed it does not charge the star and when I off the light only the star in fluorescence light glow.

My experience of lasik surgery

This time I am not going to write about experiment but just want to share my experience of the lasik surgery. I did a Intralase custom lasik at The lasik surgery clinic just 2 days ago. Now I can see perfectly with no side effect. They even recommend me to put eye drop every hour but I am so comfortable that I did not put it every hour as I don't think I need it.

The clinic I went to has a lot of patient doing lasik. At first I really doubt how they can manage with so many patient but everything was fast and I did not need to wait too long. Their skill is also good, maybe they are expert in doing lasik since they have so many patient everyday.

On the day of my surgery, I reach there at 6pm and they brought me to the recovery room and told me to read and sign the agreement for the surgery. I was told to rest and wait on an armchair (No bed for resting) with curtain to separate in between patient. I can say there are about 15 such cubicle in that room for patient to rest or wait for the treatment. The staff are nice and ask me whether I need a drink and explain to me what I will expect later for my treatment and show me the medication I would need after my surgery.

Around 6.30pm, I was asked to walk to the surgery room (Not push using a bed). There are 2 machine there. One was to cut my cornea another was to fix my eye using laser. No pain was experience as they have numb my eyes. But the scary thing is that you can see they use a seeker to scape your eye as they need to put my cornea back after the lasik. After the surgery I have to walk back to my recovery cubicle, then they put on the eye shield for me. My eye feeling is like wind blowing onto your eye so is quite dry and you will tears, the eyes will be quite red too. But this sensation is bearable.

Later I was sent home and ate the sleeping pills they gave me as instructed. So I just sleep throughout till the next morning without feeling any discomfort. So I look myself in the mirror. GREAT! I can see clearly even though there maybe some halo around the thing I see. My eye is not red anymore and no discomfort. However I just apply eye drop as a protection. Maybe mine is the intralase technology which claim to have less side effect and prevent dry eye.

Anyway I can happily go back to Paragon for my review at 2.30pm on that day without any help as I can see clearly already. Until now everything is fine and I am happy with the result. However just an advice is that if you want good customer service, my clinic is just average as they have to handle many cases as I think they are too popular. However their skill and technology is not bad since I don't experience any discmfort.

I do not need to wait too long even though there are alot of people, so their management in timing is still not bad. I do not know how other lasik clinic works but I just don't like to walk into the surgery room myself and walk back into that small cubicle after my surgery.

Do consider lasik if you have short sightheness as the surgery is simple and fast and you can break free with your spectacles after that. However do take care your eyes after the surgery as you may be prone to eye infection after the surgery.

Highlighter will glow in UV light

Just that I am doing on something on luminescence. I saw a video where they use the chemical inside the highlighter and mix it in water. Then under UV light it will glow. I did not try out this experiment, but I just highlight a piece of paper with highlighter and see it under UV light (sometime people called it black light). True enough, it glows. So I can say if you extract out the chemical inside the highlighter and mix it in water it should be able to glow. Do give it a try and tell me whether I am correct.

Glow in the dark mountain dew does not work

I think most of you may have seen and heard about the glow in the dark mountain dew. There are other video that claim that the experiment is fake. I tried it out myself. True enough IT IS FAKE. As seen in the video, they add in baking soda, and hydrogen peroxide into 1/4 full of mountain dew.

The brand I use is different from them as Singapore does not sell those brand. I use the baking soda which comes from a red tin (forgot the brand already). I use my 20vol hydrogen peroxide that is available in my lab. As I don't see hydrogen peroxide sold commercially.

As seen in the video, I drank the mountain dew until 1/4 of it is left in the bottle. Followed by adding a bit of baking soda then 3 capful of 20 vol hydrogen peroxide. Then shake well. In the end NOTHING HAPPEN except for the bubbles created while shaking.

So don't waste your time doing this experiment and waste your mountain dew where you can drink it to quench your thrist.

The effect of acid and base on universal indicator.

I happen to see a video from steve spangler which demonstrate on the effect of milk of magnesia (a kind of liquid antacid) on acid with universal indicator. The colour change of the solution from red to purple was awesome. The video can be found in steve spangler website. The colour change slowly is because the substance in milk of magnesia dissolve slowly in acid, so it will neutralise the acid slowly instead of neutralizing the acid straight away when added.

As I was preparing for the experiment on the effect of pH on the universal indicator so I think the experiment steve spangler did will be good to show the student as a demonstration. I cannot get milk of magnesia in Singapore so I tried those antacid pill by crushing them into powder and mix in water.

To my surprise, antacid pill is acidic. I don't know why, may have to ask the manufacturer. The 2 antacid pill I tried is Wei Sen U & Gelusil Antacid. So I created something quite similar to milk of magnesia which is calcium hydroxide solution. It gives a milky appearance (like milk of magnesia) as it does not dissolve fully in water and is alkaline. Somehow it works and it can be seen in this video that is taken during the experiment. The change is quite fast, so in order to see the yellow colour in between, I reverse the reaction by adding HCl drop by drop so the colour will change slowly from purple to grey to green then yellow and finally red.

From the video, you can see that when the acid is not mixed properly, the middle is red while the side is yellow.

However calcium hydroxide do not work every time due to their solubility. So they may not be able to dissolve fully to neutralise the solution and make it turn purple. Then I tried using sodium hydroxide pellet (which is a stronger base). It works and change the universal indicator from red to purple, see this video.

It's cool right! Enjoy the video as I took a few tried in order to get such great result.

The effect of bleach on universal indicator.

I was preparing normal household reagent for the student to test on its pH. One of the reagent is bleach. I have searched in the net that bleach will gives a purple colour on the universal indicator since it is alkaline. When I tested it, it shows purple initially, but it changes from purple to green to yellow then finally colourless. This will mislead the student as they may not know what colour to record down since the colour keep on changing.

So I decided to find out why from the internet and realised that the universal indicator and any other liquid pH indicator are destroyed by bleach, rendering them useless for testing the pH. This applies to litmus paper and phenolphthalein too.

The only way to solve the problem is to adds sodium thiosulfate to the bleach solutions, it will neutralize the colour-removing effects of bleach and allow it to test with the liquid indicators. Thiosulfate reduces the hypochlorite (active ingredient in bleach) and in so doing becomes oxidized to sulfate. The complete reaction is:

4 NaClO + Na₂S₂O₃ + 2 NaOH → 4 NaCl + 2 Na₂SO₄ + H₂O

I have tried it out and it works. So in future if bleach is needed to test for its pH, neutralize it with sodium thiosulphate first before adding the liquid indicator.

Styrofoam melt in acetone

Hi all, have you seen styrofoam melts in acetone (a common component found in nail polish remover). This is an endothermic reaction. Once styrofoam add into the acetone it will melt to become a semi-solid foam. When the acetone is poured away, the semi-solid foam will harden. I have tried it myself as the video taken is not so good, so I did not add it in. Anyway the video is easily available in the net.

Regarding how it melts the styrofoam, I am still not sure. Once I know it, I will put it up in our company newsletter.

Adding Mentos to Coke

Hi I think most of you have seen this in the internet. However did you do it yourself physically to see how vigorous the reaction is? S0 this exciting experiment definitely have to add it into my blog. Actually this experiment is request by one of the chemistry teacher. He is testing the student to see whether this is a physical or chemical reaction and tell them to go back and search in the internet to explain why this reaction occurs. That's why you see the teacher demonstrating and the student is watching by the side. Sorry about the orientation of the video as I do not know how to edit and rotate it.

Anyway why this reaction will occurs? This is due to the carbon dioxide gas that is pumped in the factory. Normally the gas in soft drink stay suspended in the liquid and cannot expand to form more bubbles.

This is because water molecules strongly attract each other, linking together to form a tight mesh around each bubble of carbon dioxide gas in the soda. In order to form a new bubble, or even to expand a bubble that has already formed, water molecules must push away from each other. It takes extra energy to break this "surface tension." In other words, water "resists" the expansion of bubbles in the soda.

When Mentos is dropped into the coke, the gelatin and gum arabic from the dissolving candy break the surface tension. This disrupts the water mesh, so that it takes less work to expand and form new bubbles. Each Mentos candy has thousands of tiny pits all over the surface. These tiny pits are called nucleation sites - perfect places for carbon dioxide bubbles to form. As soon as the Mentos hit the soda, bubbles form all over the surface of the candy.

When all this gas is released, it literally pushes all of the liquid up and out of the bottle in an incredible soda blast.