The most interesting on school lessons Chemistry was a topic about the properties of active metals. We were not only served theoretical material, but also demonstrated interesting experiments. Probably everyone remembers how the teacher threw a small piece of metal into the water, and it rushed along the surface of the liquid and ignited. In this article we will understand how the reaction of sodium and water occurs and why metal explodes.
Sodium metal is a silvery substance, similar in density to soap or paraffin. Sodium is characterized by good thermal and electrical conductivity. That is why it is used in industry, in particular for the manufacture of batteries.
Sodium has a high chemical activity. Often reactions occur with the release of large amounts of heat. Sometimes this is accompanied by fire or explosion. Working with active metals requires good information training and experience. Sodium can only be stored in well-closed containers under a layer of oil, since the metal quickly oxidizes in air.
The most popular reaction of sodium is its interaction with water. The reaction of sodium plus water produces an alkali and hydrogen:
2Na + 2H2O = 2NaOH + H2
Hydrogen is oxidized by oxygen from the air and explodes, which is what we observed during the school experiment.
Reaction studies by scientists from the Czech Republic
The reaction of sodium with water is very simple to understand: the interaction of the substances leads to the formation of H2 gas, which in turn is oxidized by O2 in the air and ignites. It seems simple. But Professor Pavel Jungvirt from the Czech Academy of Sciences did not think so.
The fact is that during the reaction not only hydrogen is formed, but also water vapor, since a large number of energy, the water heats up and evaporates. Since sodium has low density, the steam cushion should push it up, isolating it from water. The reaction should die down, but it doesn't.
Jungwirth decided to study this process in detail and filmed the experiment with a high-speed camera. The process was filmed at 10 thousand frames per second and viewed at 400x slow motion. Scientists noticed that metal, entering the liquid, begins to produce processes in the form of spikes. This is explained as follows:
- Alkali metals, once in water, begin to act as electron donors and give off negatively charged particles.
- A piece of metal acquires a positive charge.
- The positively charged protons begin to repel each other, forming metallic appendages.
- The spike-like shoots pierce the steam cushion, the contact surface of the reacting substances increases, and the reaction intensifies.
How to conduct an experiment
In addition to hydrogen, alkali is formed during the reaction of water and sodium. To check this, you can use any indicator: litmus, phenolphthalein or methyl orange. It will be easiest to work with phenolphthalein, since it is colorless in neutral environment and the reaction will be easier to observe.
To conduct the experiment you need:
- Pour distilled water into the crystallizer so that it occupies more than a half volume of the vessel.
- Add a few drops of indicator to the liquid.
- Cut a piece of sodium the size of half a pea. To do this, use a scalpel or a thin knife. You need to cut metal in a container without removing the sodium from the oil to avoid oxidation.
- Remove the piece of sodium from the jar with tweezers and blot with filter paper to remove any oil.
- Throw sodium into the water and observe the process from a safe distance.
All instruments used in the experiment must be clean and dry.
You will see that sodium does not sink into the water, but remains on the surface, due to the density of the substances. The sodium will begin to react with the water, releasing heat. This will cause the metal to melt and turn into a droplet. This droplet will begin to actively move through the water, emitting a characteristic hissing sound. If the sodium piece was not too small, it will light up with a yellow flame. If the piece was too large, an explosion may occur.
The water will also change color. This is explained by the release of alkali into the water and the coloring of the indicator dissolved in it. Phenolphthalein will turn pink, litmus blue, and methyl orange yellow.
Is it dangerous
The interaction of sodium with water is very dangerous. Serious injuries may occur during the experiment. The hydroxide, peroxide and sodium oxide that are formed during the reaction can corrode the skin. Alkali splashing can get into your eyes and cause serious burns and even blindness.
Manipulations with active metals should be carried out in chemical laboratories under the supervision of a laboratory assistant who has experience working with alkali metals.
Sodium is a very reactive metal that reacts with many substances. Reactions involving sodium can occur violently and produce significant heat. In this case, ignition and even an explosion often occur. To work safely with sodium, it is necessary to have a clear understanding of its physical and chemical properties Oh.
Sodium is a light (density 0.97 g/cm3), soft and fusible (melt 97.86° C) metal. Its hardness resembles paraffin or soap. In air, sodium oxidizes very quickly, becoming covered with a gray film, which consists of Na2O2 peroxide and carbonate, so sodium is stored in well-closed jars under a layer of anhydrous kerosene or oil.
A piece of sodium the right size cut without removing the metal from the kerosene, using a knife or scalpel. Sodium is removed from the jar using tweezers. All tools must be dry! After this, sodium is freed from kerosene residues using filter paper. In some cases, the metal is cleaned with a scalpel to remove the peroxide layer, since contact of peroxide with fresh sodium surface can lead to an explosion. Sodium should not be handled by hand. Sodium scraps are fused with low heat under a layer of kerosene.
Under no circumstances should dishes that contain sodium be washed with water - this can lead to an explosion with tragic consequences. Residues of sodium are eliminated by adding alcohol, only then can water be used.
It is necessary to wear safety glasses when working with sodium. Never forget what you are dealing with - an explosion can happen at the most unexpected and inopportune moment, and you need to be prepared for this.
Reaction of sodium with water
Fill the crystallizer 3/4 full with water and add a few drops of phenolphthalein to it. Drop a half-pea-sized piece of sodium into the crystallizer. The sodium will remain on the surface because it is lighter than water. The piece will begin to actively react with water, releasing hydrogen. From the heat of the reaction, the metal will melt and turn into a silvery droplet that will actively run along the surface of the water. At the same time, a hissing sound is heard. Sometimes the hydrogen that is released lights up with a yellow flame. Sodium vapor gives it this color. If ignition does not occur, the hydrogen can be ignited. However, pieces of sodium smaller than a grain of wheat are extinguished.
As a result of the reaction, an alkali is formed, which acts on phenolphthalein, so a piece of sodium leaves behind a raspberry trail. At the end of the experiment, almost all the water in the crystallizer will turn crimson.
2Na + 2H2O = 2NaOH + H2
The walls of the crystallizer must be free of grease and other contaminants. If necessary, they are washed with an alkali solution, otherwise sodium sticks to the walls and the crystallizer may crack.
The experiment should be carried out wearing a protective mask or safety glasses. During the reaction, keep a certain distance and do not lean over the crystallizer under any circumstances. Getting molten sodium or alkali splashes into your eyes can lead to virtually guaranteed blindness.
Source www.chemistry-chemists.com
If you place a piece of sodium in water, you can cause a violent, often explosive reaction
Sometimes we learn something early in life and just take it for granted that this is the way the world works. For example, if you throw a piece of pure sodium into water, you can get a legendary explosive reaction. As soon as the piece gets wet, the reaction causes it to hiss and heat up, it jumps on the surface of the water and even produces flames. It's just chemistry, of course. But isn't there something else going on? fundamental level? This is exactly what our reader Semyon Stopkin from Russia wants to know:
What forces control chemical reactions, and what happens in quantum level? Specifically, what happens when water reacts with sodium?
The reaction of sodium with water is a classic and has a deep explanation. Let's start by studying the progression of the reaction.
The first thing you need to know about sodium is atomic level it has only one proton and one electron more than the inert, or noble gas, not she. Noble gases do not react with anything, and this is due to the fact that they are all completely filled with electrons. This ultra-stable configuration collapses when you move one element further down the periodic table, and this happens to all elements that exhibit similar behavior. Helium is ultra-stable, and lithium is extremely chemically active. Neon is stable, but sodium is active. Argon, krypton and xenon are stable, but potassium, rubidium and cesium are active.
The reason is the extra electron.
The periodic table is sorted into periods and groups according to the number of free and occupied valence electrons - and this is the primary factor in determining the chemical properties of an element
When we study atoms, we get used to thinking of the nucleus as a hard, small, positively charged center, and the electrons as negatively charged points in orbit around it. But in quantum physics the matter does not end there. Electrons can behave like dots, especially if you shoot them with another high-energy particle or photon, but if left alone they spread out and behave like waves. These waves are capable of self-tuning in a certain way: spherically (for s-orbitals containing 2 electrons), perpendicularly (for p-orbitals containing 6 electrons), and further, up to d-orbitals (10 electrons each), f-orbitals ( to 14), etc.
The orbitals of atoms in the lowest energy state are at the top left, and as you move to the right and down the energies increase. These fundamental configurations control the behavior of atoms and intra-atomic interactions.
These shells are filled due to the fact that prohibits two identical (for example, electrons) from occupying the same quantum state. If in an atom electron orbital filled, then the only place where the electron can be placed is the next higher orbital. The chlorine atom will gladly accept the extra electron since it only needs one to fill it electron shell. Conversely, the sodium atom will gladly give up its last electron, since it has an extra one, and all the others have filled the shells. That's why sodium chlorine works out so well: sodium donates an electron to chlorine, and both atoms are in an energetically preferred configuration.
Elements of the first group periodic table, especially lithium, sodium, potassium, rubidium, etc. lose their first electron much more easily than all others
In fact, the amount of energy required for an atom to give up its outer electron, or ionization energy, appears to be especially low in metals with one valence electron. From the numbers you can see that it is much easier to take an electron from lithium, sodium, potassium, rubidium, cesium, etc. than from any other element
A still from an animation demonstrating the dynamic interaction of water molecules. Individual H2O molecules are V-shaped and consist of two hydrogen atoms (white) connected to an oxygen atom (red). Neighboring H 2 O molecules briefly react with each other through hydrogen bonds(blue and white ovals)
So what happens in the presence of water? You can think of water molecules as extremely stable - H 2 O, two hydrogens bonded to one oxygen. But the water molecule is extremely polar - that is, on one side of the H 2 O molecule (the side opposite the two hydrogens) the charge is negative, and on the opposite side it is positive. This effect is sufficient to cause some water molecules - on the order of one in several millions - to split into two ions - one proton (H +) and a hydroxyl ion (OH –).
In the presence of a large number of extremely polar water molecules, one in several million molecules will break down into hydroxyl ions and free protons- this process is called
The consequences of this are quite important for things like acids and bases, for the processes of salt dissolution and activation chemical reactions, and so on. But we are interested in what happens when sodium is added. Sodium, that neutral atom with one loose outer electron, ends up in the water. And these are not just neutral H 2 O molecules, these are hydroxyl ions and individual protons. First of all, protons are important to us - they lead us to the key question:
Which is energetically preferable? Have a neutral sodium atom Na along with a single proton H+, or a sodium ion that has lost an electron Na+ along with a neutral hydrogen atom H?
The answer is simple: in any case, the electron will jump from the sodium atom to the first individual proton that comes its way.
Having lost an electron, the sodium ion will happily dissolve in water, just as the chlorine ion does when it gains an electron. It is much more energetically favorable - in the case of sodium - for an electron to pair with a hydrogen ion
This is why the reaction occurs so quickly and with such an energy output. But that is not all. We have neutral hydrogen atoms, and, unlike sodium, they do not line up in a block of individual atoms bonded together. Hydrogen is a gas, and it goes into an even more energetically preferable state: it forms the neutral hydrogen molecule H2. And as a result, a lot of free energy is formed, which goes into heating the surrounding molecules, neutral hydrogen in the form of a gas, which leaves the liquid solution into the atmosphere containing neutral oxygen O 2.
A remote camera captures close-up footage of the Shuttle's main engine during a test run in space center named after John Stennis. Hydrogen is the fuel of choice for rockets due to its low molecular weight and the abundance of oxygen in the atmosphere with which it can react
If you accumulate enough energy, hydrogen and oxygen will also react! This furious combustion releases water vapor and enormous amounts of energy. Therefore, when a piece of sodium (or any element from the first group of the periodic table) gets into water, an explosive release of energy occurs. All this occurs due to electron transfer controlled quantum laws Universe, and electromagnetic properties charged particles that make up atoms and ions.
Energy levels and wave functions electrons corresponding various conditions hydrogen atom - although almost the same configurations are inherent in all atoms. Energy levels are quantized in multiples Planck's constant, but even the minimum energy, the ground state, has two possible configurations depending on the ratio of electron and proton spins
So let's recap what happens when a piece of sodium falls into water:
- sodium immediately donates an outer electron to water,
- where it is absorbed by a hydrogen ion and forms neutral hydrogen,
- this reaction releases a large amount of energy and heats up the surrounding molecules,
- neutral hydrogen turns into molecular hydrogen gas and rises from the liquid,
- and finally, with a sufficient amount of energy, atmospheric hydrogen enters into a combustion reaction with hydrogen gas.
Sodium metal
All of this can be explained simply and elegantly using the rules of chemistry, and that is how it is often done. However, the rules governing the behavior of all chemical reactions come from even more fundamental laws: the laws quantum physics(such as the Pauli exclusion principle, which governs the behavior of electrons in atoms) and electromagnetism (which governs the interaction of charged particles). Without these laws and forces there will be no chemistry! And thanks to them, every time you drop sodium in water, you know what to expect. If you haven’t figured it out yet, you need to wear protection, don’t touch the sodium with your hands, and move away when the reaction begins!
Chemical experiments are multifaceted in their depth, complexity, and effectiveness. Remembering the most beautiful reactions, it is impossible to ignore the “pharaoh snake” or the interaction of snake venom with human blood. However, chemists go further, paying attention to more dangerous experiments, one of which is the reaction of water and sodium.
Potential for sodium
Sodium - excessive active metal, interacting with many known substances. The reaction with sodium often proceeds violently, accompanied by significant heat release, inflammation, and sometimes even. Working safely with a substance requires a clear understanding of its physical and chemical characteristics.
Sodium is not very hard in structure. It has the following properties:
- low density (0.97 g/cm³);
- softness;
- low fusibility (melt 97.81 °C).
In air, the metal quickly oxidizes, so it should be kept in closed containers under a layer of Vaseline or kerosene. Before experimenting with water, you should cut off a piece of sodium with a thin scalpel, remove it from the container with tweezers and thoroughly clean it of kerosene residues with filter paper.
Important! All tools must be dry!
When working with metal, it is necessary to wear special glasses, because the slightest careless step can lead to an explosion.
History of explosion research
For the first time, scientists from the Czech Academy of Sciences under the leadership of Pavel Jungvirt were faced with the need to study the reaction of water and sodium. by the detonation of sodium in water, known since XIX century, has been carefully analyzed and described.
The reaction of sodium with water involved immersing a piece of metal in ordinary water and was ambiguous: flashes sometimes occurred, sometimes not. Later, it was possible to establish the reason: the instability was explained by the size and shape of the sodium piece used.
The larger the dimensions of the metal, the stronger and more dangerous the reaction between sodium and water became.
Time-lapse footage of the reaction showed that within five milliseconds of being immersed in water, the metal "" released hundreds of "needles." Metal electrons instantly escaping into water lead to the accumulation of positive charge: The repulsion of positive particles tears the metal, which is why “needles” appear. At the same time, the area of the metal increases, which causes such a violent reaction.
During the reaction, an alkali is formed, which leaves a raspberry trail behind the piece of sodium. At the end of the experiment, almost all the water in the crystallizer will turn crimson.
Such a reaction requires the researcher to fully comply with safety measures: carry out the experiment wearing safety glasses, trying to stay as far as possible from the crystallizer. Even seemingly insignificant errors can lead to an explosion. Hit the smallest particle Sodium or alkali in the eyes is dangerous.
Attention! Do not try to repeat these experiments yourself!