Question

Write a short note on $pH$ of pure water and its properties.

Answer 1

Hint: $pH$ is the measure of acidity or basicity of a substance. It is basically a measure of ${H^ + }$ ions that a compound will give when it is dissolved in water. ${H^ + }$ ions are also written as ${H_3}{O^ + }$.

Complete step by step solution:
We know $pH$ is a measure of ${H^ + }$ ions concentration. It is measured as $pH = - \log ({H^ + })$ where $[{H^ + }]$ is hydrogen ion concentration. Range of $pH$ is from $0 - 14$. Species having $pH$ below $7$ are acidic in nature such species release ${H^ + }$ions and species which have pH above $7$ are basic in nature such species release $O{H^ - }$ ions. Species which have $pH$ equal to $7$ are neutral. Pure water is neutral in nature this means it is neither acidic nor basic. Concentration of ${H^ + }$ ions and concentration of $O{H^ - }$ ions is equal in water. $pH$ is sea water is slightly above $7$ because sea water has some salts dissolved in it.
Properties of water: Let's start from very basic properties.
Water is colorless (it is transparent), odorless (without any fragrance), and tasteless liquid.
It has hydrogen bonding in its molecules. It is the bonding which is between hydrogen and highly electronegative elements. Electronegativity refers to the ability to attract a shared pair of electrons.
It is polar in nature which means as a whole component is neutral but there is an asymmetrical distribution of charge inside the atom due to which it is partially positive and partially negative. It is also called universal solvent because it dissolves most of the polar substances in itself.
Density of water is $1gm/c{m^3}$. Density is a measure of mass per unit volume of substance.
Triple point of water is $0.1^\circ C$ and $0.006atm$ pressure. Triple point is the point at which three states of substance that are solid, liquid and gas coexist.

Note: Water has equal concentration of ${H^ + }$ and $O{H^ - }$ ions it means water is neither acidic nor basic. It is neutral. Species like $HCl$, ${H_2}S{O_4}$ are acidic in nature and species like $NaOH,KOH$, are basic in nature.