Abnormal density of ice and water

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Water - a mysterious liquid.This is due to the fact that most of its properties are abnormal, i.e.It differs from other liquids.The reason lies in its special structure, which is caused by hydrogen bonds between molecules, varies with temperature and pressure.These unique properties and has ice.It is said that the determination of the density can be realized by the formula ρ = m / V.Accordingly, the criterion may be set through a study of the medium mass per unit volume.

Let's look at some of the properties of ice and water.For example, the density anomaly.After the melting of the ice density increases, passing through the critical mark of 4 degrees, and only then begins to decrease with increasing temperature.However, in ordinary liquids it always decreases during cooling.This fact is a scientific explanation.The higher the temperature, the greater the velocity of the molecules.This leads to repulsion of each other, and therefore the material becomes more friable.Riddle water lies in the fact that, despite the increase in velocity of the molecules as the temperature increases, its density reduction occurs only at high temperatures.

second riddle lies in the question: "Why is ice can float on the surface of the water?", "Why is she in the river does not freeze to the bottom?"The fact that the density of ice is lower than that of water.A melting process of any other liquid its density is smaller than that of the crystal.This is due to the fact that in the latter molecules have a certain periodicity and are arranged regularly.This is typical for crystals of any substance.However, apart from this, they have a molecule "packed" tight enough.In the process of melting of the crystal regularity disappears, which is possible only with a less dense molecular bonding.Accordingly, the density of the material is reduced in the melting process.But this criterion varies quite a bit, for example, the smelting of metals, he drops an average of 3 percent.However, the density of ice is less than the density of water at once ten percent.Therefore, we can say that this leap is abnormal, not only its sign, but also value.

Explains features of these mysteries of the ice structure.It is a network of hydrogen bonds, where each node of four pieces.Therefore, the grid is called a quad.All corners there are qT, so it is called tetrahedral.Moreover, it is composed of six-membered rings curved shape.

peculiarity of the structure of solid water is that the molecules are loosely packed in it.If they are in close relationship, the density of the ice would be 2.0 g / cm3, but in reality it is 0.92 g / cm3.This was to follow the conclusion that the presence of large spatial volumes should lead to instability.In fact, the grid becomes less strong, but it can be reconstructed.Ice - is so strong material that even the ancestors of modern Inuit learned to build their huts out of it.To this day, the inhabitants of the Arctic ledobeton used as a building material.Accordingly, when the pressure is changing the structure of ice.It is this stability is the main property of the hydrogen bonds between the molecules of H2O nets.Accordingly, each water molecule in liquid state retains four hydrogen bond, but the angles are different from qT, this leads to the fact that the ice density less than water.