Chemistry

Ionic Water Balance (KW)


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)

KW

0

0,11.10-14

40

3,0.10-14

100

51,3.10-14

Types of aqueous solutions

Aqueous solutions of chemical substances can be classified into three types:
- acidic solution
- basic solution
- neutral solution

Acid solution

It is the solution that contains the H + ion concentration higher than the OH- ion concentration.

Basic solution

It is the solution that contains the concentration of the OH- ion higher than the concentration of the H + ion.

Neutral solution

It is the solution that contains the concentration of the OH- ion equal to the concentration of the H + ion.