The water

Two-thirds of the Earth's surface is the water, whose mass is 1,5*1021 kg. The water makes the cycle in nature. On the surface of oceans and seas the water evaporates rapidly, forming clouds. From the clouds, it is poured over the Earth, it seeps through the soil, forming a considerable size of the underground reservoirs of fresh water. And of them originate the river.

Two-thirds of the Earth's surface is the water

Because such a large prevalence in nature, the water has become the standard of many of the physical properties. The density and the viscosity her mistaken for one. The water solidification temperature is taken as zero, and the boiling point 100 degrees (Celsius).

The water in large amounts spent on daily needs of man, and it should be fresh and free of any impurities. Even in ancient Rome delivered daily to 3 liters of clean water per inhabitant. But if we talk only about the amount that a person should consume daily to maintain life, it is only 2,5 liters. On the other hand, 60 years of life a person drinks 50 m3 of water rail car...

The water is used in a variety of instruments and devices. It turns the wheels of water mills and water turbines rotors. In ancient Greece it was known water clock clepsydra, an analog which is an hourglass. The greeks put clepsydra in court. Prosecutor and defense counsel withdrawn the same time, which is measured by the volume of flowing water.

The water is the best solvent. It dissolves almost all inorganic substances and many organic substances. World Ocean water contains dissolved more than 60 elements of the periodic system. So, gold is contained in the oceans so much that for every person on Earth will get three kilograms.

On the periodic table of elements possible to predict all the properties of any substance. The water there is no exception. At normal atmospheric pressure, water would have to boil at -70 degrees Celsius. There is just a minus, not a dash. That is, it must boil at 170 degrees Celsius lower than it really boils. Freeze the water should be at -90 degrees Celsius, and not at 0 degrees Celsius. And ice formed at the same time, would have to sink immediately, rather than float on the surface of the water. From bad swirling tap water should not have to drip, and would have to pour a thin stream. A sugar in water would dissolve slowly and poorly in the best case to a few grains. So honey in nature should not be. And sweet tea, jam and also do not have special rights to exist. When cooled below 4 C water expands. It also expands upon solidification, and the ice is lighter than water. In winter, the ponds, lakes, rivers, preserved under a layer of ice up to very large uncured cold water with a temperature of 4 degrees Celsius. If water did not have such an anomaly, ponds were frozen to the bottom, and all the fish died. Water has many other anomalies. Since its viscosity decreases with increasing pressure (from all other liquids the viscosity increases). The speed of sound in water increases with increasing temperature (all other liquids, it decreases). The thermal conductivity and the permittivity of water is greater than that of all other liquids. As the surface tension of water is second only to mercury, in the heat of fusion second only to ammonia. The specific heat of water is three times greater than that of other common substances. As temperature increases from 0 to 7075 degrees Celsius compressibility of water decreases, whereas all other fluid compressibility increases. For this indicator, it becomes similar to a conventional liquid only near the boiling point.

The story of the next water anomaly is best to start with a description of sensations inexperienced traveler, first came to the Sahara desert. The traveler, of course, assumed that in the desert is hot, but that to such a degree... The sun went down! Immediately becomes cooler. Even cooler. Very cool. Cold. Very cold. The sun came up... Yes, the heat capacity of water - and here the question is about this property - much higher than the heat capacity of the vast majority of other substances. In areas rich in water, even in the scorching sun strongly temperature rises relatively slowly, a significant portion of the incoming heat is trapped water. But even after the light disappears behind the horizon, the temperature in such areas falling too slowly, the water gradually gives a significant amount of heat the air, it accumulated. That's why water is an excellent climate control. Now it becomes clear that the traveler had to consider. Water is not present in the Sahara. In the Sahara there is sand. The specific heat of the sand five times less than that of water. Therefore, during the day under the hot sun quickly heats the sand - it takes a bit of heat. At night, giving the poor their entire supply of heat, the sand cools down quickly. Therefore, in the southern desert at night it is very cold.

Apparently, the reader is prepared to ensure that the largest and the latent heat of vaporization of water is an absolute champion. Immediately it should be noted this anomaly is certainly useful. If the water would not have a high heat of vaporization, our planet would not be rivers, lakes and oceans. Most of the water would be in a vapor atmosphere. Our planet would be enveloped in a dense and impenetrable atmosphere, consisting almost entirely of water vapor! The high value of the latent heat of vaporization of water also explains the regulatory action of water on the Earth's climate. The water evaporates and cools the air, spilling rain and heats it.

Naturally recall one water anomaly associated with the properties of crystalline modification of the substance. This is an abnormal change in the properties of ice with a change in pressure. Skater easily rolls on the ice because of pressure exerted by the blade on the ice skates, ice melts and forms a liquid water is an excellent lubricant. This is known to all. But not everyone knows that this was not to be. All substances with increasing pressure increases the melting point. In the water, on the contrary: the pressure drop leads to a lowering of the melting point of ice.

Have you ever wondered how the water rises from the roots to the tops of tall trees? In accordance with the known laws of mechanics creating the pressure difference is impossible to carry out a spontaneous rise in water to a height of 10 m. In plants, water is the capillary rise nature. Omitting a capillary in the liquid, the liquid rises. The rise will be greater the smaller the diameter of the capillary and the higher surface tension of the liquid.

These amazing properties of water demand explanations from a unified position. That no one has managed to do. It can be concluded that plain water is not the study of matter.