Physical properties of water

by George Braileanu, XI B class
“Vasile Alecsandri” High School, Galati, Romania

The two extreme temperatures of water, of solidification and boiling at natural pressure are 0 ºC and 100 ºC in the Celsius scale.

Water is liquid a large interval of temperature (0 ºC and 100 ºC). This anomaly is attributed to the molecular association of water trough bonds of hydrogen.

The bonds of hydrogen are realized with the molecules which contain covalent hydrogen to a powerful electro-negative element which has small volume and electrons which do not participate.

The hydrogen bond is electrostatic, weaker than the covalent bond and it doesn’t imply in common posing of electrons.

The water density varies with temperature:

At freezing it forms a second bond of the hydrogen at the oxygen atom, reason why ice has an aerie structure which determines the growth of the volume and decrease of the density.

Through freezing waters increases its volume by 9 per cent. This explains why the buckets and glass break. The majority of liquids increase their volume of solidification. It is known that +4 ºC water has ρmax=1 g/cm³ which is because of the fact that the water is formed of (H₂O)₂; this means the existence of two bonds of hydrogen.

The water in vapor state is formed from free molecules (n=1)