Ice is a solid in the state of aggregation, which is characterized by a gaseous or liquid form at room temperature. The properties of ice began to be studied hundreds of years ago. About two hundred years ago, scientists discovered that water is not a simple compound, but a complex chemical element consisting of oxygen and hydrogen. After the discovery, the water formula began to look like H 2 O.
Ice structure
H 2 O consists of two hydrogen atoms and one oxygen atom. In a calm state, hydrogen is located at the tops of the oxygen atom. Ions of oxygen and hydrogen should occupy the vertices of an isosceles triangle: oxygen is located at the apex of a right angle. This structure of water is called a dipole.
Ice consists of 11.2% percent hydrogen, and the rest is oxygen. The properties of ice depend on its chemical structure. Sometimes it contains gaseous or mechanical formations - impurities.
Ice is found in nature in the form of a few crystalline species that stably maintain their structure at temperatures from zero and below, but at zero and above it begins to melt.
Crystal structure
The properties of ice, snow and steam are completely different and depend on the structure of the crystals. In the solid state, H 2 O is surrounded by four molecules located in the corners of the tetrahedron. Since the coordination number is low, the ice may have an openwork structure. This is displayed on the properties of the ice and its density.
Ice forms
Ice is a naturally occurring substance. On Earth there are the following varieties:
- river;
- lakeside;
- nautical;
- firn;
- glacial;
- unpaved.
There is ice directly formed by sublimation, i.e. from a vaporous state. This form takes on a skeletal shape (we call them snowflakes) and aggregates of dendritic and skeletal growth (hoarfrost, hoarfrost).
One of the most common forms are stalactites, i.e. icicles. They grow all over the world: on the surface of the Earth, in caves. This type of ice is formed by draining drops of water at a temperature difference of about zero degrees in the autumn-spring period.
Formations in the form of ice strips that appear along the edges of water bodies, on the border of water and air, as well as along the edge of puddles, are called ice barriers.
Ice can form in porous soils in the form of fibrous veins.
Ice properties
The substance may be in different states. Based on this, the question arises: what property of ice is manifested in a particular state?
Scientists distinguish physical and mechanical properties. Each of them has its own characteristics.
Physical properties
The physical properties of ice include:
- Density. In physics, an inhomogeneous medium is represented by the limit of the ratio of the mass of the substance of the medium to the volume in which it is enclosed. The density of water, like other substances, is a function of temperature and pressure. Typically, a constant water density of 1000 kg / m 3 is used in the calculations. A more accurate density indicator is taken into account only when it is necessary to carry out very accurate calculations in view of the importance of the result of the density difference.
When calculating the density of ice, it is taken into account which water has become ice: as you know, the density of salt water is higher than distilled. - Water temperature. Typically, water crystallizes at a temperature of zero degrees. Freezing processes occur irregularly with the release of heat. The reverse process (melting) occurs when the same amount of heat is absorbed that was released, but without jumps, but gradually.
In nature, there are conditions under which supercooling of water occurs, but it does not freeze. Some rivers retain the liquid state of water even at a temperature of -2 degrees. - Heat capacity. This is the amount of heat that is absorbed by heating the body every degree. There is a specific heat capacity, which is characterized by the amount of heat required to heat a kilogram of distilled water by one degree.
- Compressibility. Another physical property of snow and ice is compressibility, which affects the decrease in volume under the influence of increased external pressure. The reciprocal is called elasticity.
- The strength of ice.
- The color of ice. This property depends on the absorption of light and the scattering of rays, as well as on the amount of impurities in frozen water. River and lake ice without impurities is visible in soft blue light. Sea ice can be completely different: blue, green, blue, white, brown, have a steel tint. Sometimes you can see black ice. It acquires such a color due to the large number of minerals and various organic impurities.
Mechanical properties of ice
The mechanical properties of ice and water are determined by the resistance to environmental influences in relation to the unit area. Mechanical properties depend on structure, salinity, temperature and porosity.
Ice is an elastic, viscous, plastic formation, but there are conditions under which it becomes hard and very fragile.
Sea ice and freshwater are different: the first is much more plastic and less durable.
When passing ships, the mechanical properties of ice are necessarily taken into account. It is also important when using icy roads, crossings and more.
Water, snow and ice have similar properties that determine the characteristics of a substance. But at the same time, many other factors influence these indications: ambient temperature, impurities in the solid, and the initial composition of the liquid. Ice is one of the most interesting substances on Earth.