Category : Chemistry news

Transition Element (Common Last Topic)

Mr Khemistry


Minister Chan just announced on 27th July 2021 that the common last topic will be taken out of the A levels examinations this November.

For those of us who already did the topics, it seemed like time was wasted to teach this topic. But the good thing is students will have less to revise this year.

Rightfully so as the multiple disruptions due to tightening/loosening covid measures surely affected the students’ ability to focus.

With the time now freed up from revising transition elements, we can now focus on the topics that are left.

Focus on the Theme: Creative Writing for PSLE Excellence

For those of you who have not done up a revision schedule, now is the best time to plan it.

IMHO, A levels is not something you can decide to pia overnight and score a distinction for it. Far from it.

Unless you consistently revise and put in the effort to practise, it is almost guaranteed that you will not get a quality grade. (A or B)

Such is the rigour of this national examination.


If you need a crash course or intensive revision classes, feel free to drop me a whatsapp @ 83322534.

Will see what i can do to help! Gambatte!


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Dettol disinfectant spray

Mr Khemistry

Dettol disinfectant spray

dettol disinfectant spray

Dettol disinfectant spray – Can it kill the novel corona virus?

Kekulé, skeletal formula of chloroxylenol Chloroxylenol, also known as para-chloro-meta-xylenol (PCMX), is an antiseptic and disinfectant which is used for skin disinfection and cleaning surgical instruments. It is also used within a number of household disinfectants and wound cleaners. It is sold in a number of formulations and under a number of brand names including Dettol. (Source: Wikipedia)

Dettol’s company RB, has clarified that it does not have access to this new corona virus and therefore have not done testing on it before. So that is no evidence that it can kill the virus. It can probably kill flu virus which has been tested before.

But this doesn’t stop us from spraying it over common areas, cutting down the amount of germs in our common spaces will do us good in this period. I wish we will all become more socially responsible to wear face masks when we are sick. Of course it feels uncomfortable and older folks probably despise wearing it but it is the way to go.

Singapore is becoming more and more densely populated and we can all do better by increasing our level of personal hygiene. Don’t you agree? 🙂

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Alcohol-based hand sanitizer

Mr Khemistry

Alcohol-based hand sanitizer


Alcohol-based-hand-sanitizer. Masks and Hand Sanitizer are all the craze now, no thanks to the Corona Virus. Gifts of masks or hand sanitizers are probably more welcomed than bak kwa.

Since i’m currently teaching the topic of alcohol for the J2 classes, let’s look at how important alcohol is in the hand sanitizers.

Basically, hand sanitizers work by disrupting the cell membrane of a bacterium and the outer coat of the virus. The alcohol (isopropanol or ethanol) content has to be at least 60% to be effective, 70% being the best and most effective. Any lesser and they’re not going to help much. Also, if our hands have dirt or grime on them, hand sanitizers wouldn’t be as effective. If our hands have dirt or grime, we have got to wash our hands with soap and water for at least 20 seconds.

Another thing to note for alcohol-based-hand-sanitizer is you’ve got to use enough and rub it in thoroughly until it dries, otherwise it wouldn’t work as well as it should.

So yes, hand sanitizers does help in the fight against corona virus, but do check the alcohol content before getting it.

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Reaction Kinetics

Mr Khemistry

Reaction Kinetics

Reaction Kinetics – A team of scientists at Harvard university have built an apparatus which can achieve ultra cold temperatures. This allows them to capture reaction mechanisms previously elusive as they occur too quickly.

Now, they not only performed the coldest reaction yet, they discovered their new apparatus can do something even they did not predict. In such intense cold — 500 nanokelvin or just a few millionths of a degree above absolute zero — their molecules slowed to such glacial speeds, Ni and her team could see something no one has been able to see before: the moment when two molecules meet to form two new molecules.”

Coldest reaction


Wow! Scientists are able to actually replicate such low temperatures in their labs! Nano is 10^-9 times, that’s like 0.000000005 K.

With such low temperatures, the kinetic energy in the molecules will be so low they will literally be “crawling”. Imagine Maxwell Boltzmann distribution with just one thin line near zero Kelvin.

This will enable scientists to capture images of what actually happens in the transition state. Previously, the transition state cannot be captured. With this new breakthrough, we will be able to validate or disprove the transition state theory. Exciting times! 🙂

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