The Properties Of Water

The importance of water can never be denied. Whether we refer to its importance for the human body or for the other living creatures, water is an essential component of life. Water is an inorganic, colourless, odourless and tasteless substance. It is the main component of the planet- Earth’s hydrosphere. Water is also the fluid in all living organisms. H2O is the chemical formula that represents this inorganic chemical substance. 

Vital for all forms of life, water has its specific properties. The properties of water are essential to understand as it supports in understanding numerous chemistry concepts and chemical equations. 

Physical properties of water

Water has a few significant physical properties. Although these properties are familiar to numerous people as water is present everywhere. 

• Water is a tasteless, odourless and colourless inorganic chemical substance.
• A single molecule of water (H2O) consists of two hydrogen atoms covalently bonded with one Oxygen atom. 
• Water has three physical states- liquid (water), solid (ice) and gas (vapour). The liquid phase of water is the most common phase of water present within the Earth’s atmosphere and surface. 
• It has a high specific heat capacity, which is equal to 4184 J/(kg . K) at 25°C. 
• Water also has a high heat of vaporisation, equal to 40.65 kJ/mol or 2257 kJ/kg at the normal boiling point.
• Water has a specific enthalpy of fusion, which is equal to 333.55 kJ/kg at 0 °C.  
• The density of water is 1 gram per cubic centimetre. 
• Generally, water is a miscible liquid with numerous liquids like ethanol in all proportions. But, with most oils, water is immiscible and forms layers on the top. 
• The high dielectric constant makes water an excellent solvent. Substances that dissolve in water are known as hydrophilic substances, and the ones that do not dissolve in this solvent are known as hydrophobic substances. 
• It has a high surface tension of 71.99 mN/m at 25 °C.

Chemical properties of water

• Amphoteric nature of water

Water is known to be amphoteric. It means it can act as both acid and base. The Hydrogen atoms in a water molecule enable it to act as an acid in a reaction. At the same time, the Oxygen atom in a water molecule consists of two lone pairs. One of these lone pairs can be used to form a bond H+. Hence, the water molecule can act as a base too. 

• Redox reactions

The oxidation state of Hydrogen in water is +1, and for Oxygen, it is -2. It oxidises hydrides, alkali metals and some alkaline earth metals.

Water is redox reaction:

2Na + 2H2O→H2 + 2Na+ 2OH-

• Water electrolysis

A water molecule can be split into its constituent elements- Hydrogen and Oxygen with water electrolysis. Bypassing electric current through water, electrolysis can be carried out.

The cathode half of this electrolysis reaction is-

2H+ + 2e-→H2

The anode half of this reaction is- 

2H2O→O2 + 4H+ + 4e-

• Self-ionisation

Liquid water exhibits self-ionisation and produces hydronium and hydroxide ions. 

2H2O⇌ H3O+ + OH-

• Water’s organic chemistry

Water is a hard base. Hence, it readily reacts with organic carbocations. Adding water to an organic molecule cleaves the molecule into two, and hydrolysis occurs. Water is also a leaving group in the E2 elimination and SN2 substitution reactions. 

Conclusion

Water is undeniably crucial for all life forms. The universal solvent has its IUPAC name as oxidane. The unique physical and chemical properties of water helps to understand the chemistry of water and also the chemical reactions of this polar inorganic substance. The biological role of this universal solvent is also crucial to understand, and to understand this; one must be familiar with all the properties of water- both physical and chemical.