It is a colourless and tasteless liquid. Its physical properties are given in Table 9.3 along with the physical properties of heavy water.
The unusual properties of water in the condensed phase (liquid and solid states) are due to the presence of extensive hydrogen bonding between water molecules.
This leads to high freezing point, high boiling point, high heat of vaporisation and high heat of fusion in comparison to H2S and H2Se.
In comparison to other liquids, water has a higher specific heat, thermal conductivity, surface tension, dipole moment and dielectric constant, etc. These properties allow water to play a key role in the biosphere.
The high heat of vaporisation and heat capacity are responsible for moderation of the climate and body temperature of living beings.
It is an excellent solvent for transportation of ions and molecules required for plant and animal metabolism. Due to hydrogen bonding with polar molecules, even covalent compounds like alcohol and carbohydrates dissolve in water.