|- IN MEMORIAM -|
|Юрий Яковлевич Фиалков|
|Yu. Ya. Fialkov
«The Extraordinary Properties of Ordinary Solutions»
Английский перевод книги «Необычные свойства обычных растворов».
Переводчик Борис Кузнецов.
|Полный текст — в разделе «книги»|
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Yu. Ya. Fialkov «The Extraordinary Properties of Ordinary Solutions»
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On Dry Lemonade and About This Book
It is a hot July day. Feeling thirsty, you look around for a nearby soda fountain and find none. But your eyes catch the sign at the top of a kiosk. Styled in fanciful Old-Slavic letters, it promises Russian kvas, a soft drink perhaps as popular with Russians as Coca-Cola with Americans. No, there is not a drop of kvas left, the girl behind the counter says. Nor a bottle of Buratino (another Russian favourite). What she can offer is lemonade. Hopefully, I opt for two. The girl holds out — no, not the familiar paper cups full of the bubbling liquid. In her hand are two small white packages stuffed with a crackling powder. That is dry lemonade. Well, your thirst has to wait until you are back home. But that is a good point from which to start with a book about solutions — this book.
Of course, it would be more appropriate to begin by stating that the subject of solutions is extremely important, more important than anything else. For solutions are everywhere around us. Tea is a solution. A perfume is a solution. A sea wave is a solution. The pickle for cucumbers is a solution. Even cucumbers themselves are solutions. But it is not enough just to declare that solutions are vitally important. This must be proved. And this is the object of the book you are going to read.
Deep in thought about the solutions so amazingly present everywhere, you get back home, take a package of dry lemonade and, following the simple instructions stamped on it, empty its contents in a glass and fill it with tap water. In an instant, the powder dissolves, and gas bubbles stream violently to the surface. You take a sip and feel satisfied — the drink is sweet and, most important, full of fizz.
Of course, the fizz, or gas, that goes up as bubbles in the do-it-yourself lemonade is not stored in the package. It comes from a chemical reaction. The point is that the powder contains (in addition to sugar) baking soda and citric acid. The two eagerly react with each other to form the sodium salt of citric acid and gaseous carbon dioxide. Simple as that, and no tricks.
Simple? No tricks? Why is it then, you may ask, that the soda and the acid do not react when the powder is dry? Why is it that the mixture has to be dissolved for the reaction to take place?
The answer is, Corpora non agunt soluta, which is the Latin for "Bodies (substances) do not react unless dissolved". Alchemists discovered this rule many centuries ago.
We take it for granted that chemical reactions take place in solutions, but hold this fact at the back of our minds or even completely forget about it. To prove the point, I challenge you to take what might pass for a psychological test. Describe in words what you see with your mind's eye when you are told: "When caustic soda and hydrochloric acid are brought together, a neutralization reaction occurs according to the equation: NaOH + HCl = NaCl + H2O".
I'm prepared to bet against any odds that what you see in your mind is a flask of alkali from which a sample is poured into a test tube to which an amount of acid is added from another flask. That's all, and nothing more. But, unless you know already, any reference book on chemistry will tell you that caustic soda, NaOH, is a crystalline solid melting at 318°C, and hydrogen chloride, HCl, is a gas which turns to liquid at -84°C. Now you can see for yourself that the reactants are no liquids.
In our hypothetical test we poured together solutions of the reactants in water, rather than the substances themselves. That's obvious. But it is not so obvious what water has to do with the reaction and why. In fact, some water is produced when the alkali reacts with the acid (so, in accord with the laws of chemical reactions the added water should only meddle with the reaction). Moreover, as is clearly seen from the reaction equation, the reactants do not need water. Yet, although they do not need water, nothing can happen without it. In some mysterious way (to be explained later), water takes part in our reaction and, indeed, in an overwhelming majority of other chemical reactions. As chemists well know, 199 reactions out of 200 can only take place in solution.
This fact alone could well support our statement that solutions are very important. And we could add many more such facts.
The title of this book promises to take up some extraordinary properties of solutions. Some readers may disagree with the choice of the word. They may argue, for example, that there is nothing extraordinary in the fact that salt solutions can conduct electricity or that a solution would freeze at a lower temperature than a pure solvent. Science has explanations for everything, they may add, what is unclear today will be clarified tomorrow.
Nothing extraordinary ? Well, it depends. It depends on how you look at things. Here is a tree, an ordinary tree. But if you stop to think of how its luxuriant foliage has grown out of carbon dioxide and water, you will feel it is a wonder.
One sagacious man has once said that science begins by seeing unusual in the usual. Everyone had seen things fall when let go from one's hand, but only Galileo was intrigued by what he saw. A good many people had admired bright sun rays, but only Newton saw something striking in sunlight. Everyone had seen water freeze, but only Lomonosov treated this as a wonder.
That is why every book on science is always an invitation to see unusual in the usual. I, too, invite you to share my amazement at the extraordinary, extremely extraordinary properties of ordinary solutions.
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|Unchecked text of the book created using optical character recognition (OCR)|