Pure water ionizes very weakly as follows:
The equilibrium constant KC is given by the expression:
Since water is in the liquid state, its concentration remains constant, so it does not participate in the formula and we can multiply it by KC, obtaining a new constant. In this case, KW, ie the ionic product of water.
KW is the ionic equilibrium constant of water. The letter w comes from the english word water which means water. This constant depends on the temperature. At 25 ° C the ionic equilibrium constant of water is:
Unity is dimensionless, as are the other equilibrium constants. Here are some constants for different temperatures:
TEMPERATURE (° C)
Types of aqueous solutions
Aqueous solutions of chemical substances can be classified into three types:
- acidic solution
- basic solution
- neutral solution
It is the solution that contains the H + ion concentration higher than the OH- ion concentration.
It is the solution that contains the concentration of the OH- ion higher than the concentration of the H + ion.
It is the solution that contains the concentration of the OH- ion equal to the concentration of the H + ion.