Ionic product of Water
Water is a weak electrolyte and undergoes selfionistion to a small extent.
“The product of concentrations of 
and 
ions in water at a particular temperature is known as ionic product of water.” It is designated as 
.
⇌ 
; 
;
;
The value of increases with the increase of temperature, i.e., the concentration H+ and OH– ions increases with increase in temperature.
The value of at 
is 
mole/litre. Since pure water is neutral in nature, ion concentration must be equal to ion concentration.
or 
or 
or 
This shows that at , in 1 litre only 
mole of water is in ionic form out of a total of approximately 55.5 moles.
Thus when, 
; the solution is neutral
; the solution is acidic
; the solution is basic
