The Joy of Chemistry (5B05)

日期: 09/02/2023

Good morning, principal, teachers and fellow schoolmates. I am Mak Wing Yan, Yana from class 5B. “Challenging”, "rote-learning" or “demanding” are these the first words that come to your mind when you think of chemistry? Today, I would like to introduce you to "The Joy of Chemistry," a book by Cathy and Monty that might completely alter how you feel about chemistry.


This book is divided into two sections:  the fundamental principles of chemistry and a survey of some of the specialised fields of chemistry.  In contrast to other chemistry books, this book not only discusses fundamental concepts like atoms, redox reactions, and neutralisation but also includes examples of relevant daily-life experiments that we can perform on our own with step-by-step instructions and results observation. In the following, I will talk about a few experiments outlined in the book.


I believe that many of you have heard of Oobleck, which in Chinese is 非牛頓流體. It feels relatively solid when you pick it up and squeeze it, but if you hold it in your palm, it appears to "melt" into a puddle.  You can make it simply by mixing cornstarch and water in the proper ratio. The property of Oobleck - not quite solid or liquid- is because cornstarch traps water, like a sponge, but starch's structure is less rigid. As a result,  it can flow with its water load. Although the properties of Oobleck seem entirely different from the reactants - cornstarch and water, it is not a chemical reaction. Instead, it is a physical change because only the physical properties of the reactants have changed, not their chemical properties.


There is a kind of dye whose colour changes when it mixes with another solution of a different pH level. This type of dye is called an acid-base indicator. The purple-cabbage indicator, fish-tank indicator, and swimming-pool indicator are a few examples we can use at home. Let's discuss the purple-cabbage indicator as an example. It turns light lavender when mixed with water. However, it turns blue when combined with a saturated baking soda solution. It is because baking soda solution is alkaline which is slippery and bitter in nature. In addition, it turns bright pink when combined with a vinegar solution, an acidic sour solution. Now if we carefully mix the baking soda solution and vinegar solution, the purple-cabbage indicator inside will turn light lavender as neutralisation occurs in which the acidic property of vinegar and alkaline property of baking soda cancel each other out and water is produced. In other words, they are balanced.


In addition to these experiments, the book also covers a few entertaining chemistry-related facts. It is well-known that the atmosphere consists of much more nitrogen than oxygen, with a comparison of 78% and 21%. The phenomenon is caused by nitrogen's lower level of chemical activity and participation in chemical reactions compared to oxygen. Nitrogen is hence stable in the atmosphere. However, it is inconceivable that such an unreactive element could be used in the chemistry of nitrogen airbags, which serve as a cushion to protect life in vehicles. At the same time, another compound of nitrogen, nitrogen dioxide, can irritate our eyes, skin and mucous membranes. It contains huge chemical differences with destructive and nurturing characteristics at the same time. The explanation is that nitrogen atoms can gain 3 electrons or lose 3 or 5 electrons to form a chemical bond with others, which enables them to undergo many metamorphoses and produce a variety of compounds.


This delightful and richly informative book challenges the perception of chemistry as too complicated to bother with and too clinical to be fun. In fact, Chemistry begins with our curiosity and experiments, which is then followed by our intuition and logic. The objective of this book is to increase public access to chemistry. Chemistry is not just a subject for people who study science, but also for those who are interested in the scientific principles that make up our world. Consequently,  it is hoped that students who do not study Chemistry can still be in touch with chemistry in their everyday experience. It is never too late to indulge yourself in the joy of chemistry. Thank you.


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