Dissociation of water. Ionic product of water

Degree and constant of electrolyte dissociation.

Substance solutions of which pass the electric are called as electrolytes.

d- Degree of electrolyte dissociation

d=n/N*100 %

In which: n-number of dissociate molecules; N-is a total number of molecules taken for dissolution;

Degree of α depends on:

1) Nature of solution, α – is equal O for non-electrolytes;

2) Nature of solvent (polar or nonpolar);

3) Temperature-the more temperature the more dissociation;

4) Concentration-the less concentration the more degree of dissociation;

Strong electrolytes α>30%	Intermediate 3%<α<30%	Weak α<3%
AlCl3, H2SO4, NaOH, LiOH, Ba(OH)4, HCl, HNO3, almost all salt dissolved in water.	H3PO4, H2 SO3 and etc.	NH4OH, all bases undissolved in water, H2O itself, HF, HCN, all organic acids.

Dissociation constant

For reversible dissociations in a chemical equilibrium

AB<=>A + B

the dissociation constant Kd is the ratio of dissociated to undissociated compound

where the brackets denote the equilibrium concentrations of the species.

Pure water is not really pure. The purest water contains some hydronium ions and hydroxide ions. These two are formed by the self-ionization of two water molecules. This happens rarely. The process is an equilibrium where the reactants, intact water molecules, dominate the mixture. At equilibrium the molarities for the hydronium ion and hydroxide ion are equal. [H3O1+] = [OH1-]

The animation shows one of the effective collisions between two water molecules to form hydroxide and hydronium ions. The process is reversible. Water normally exists as a mixture of molecules, hydroxide ions and hydronium ions. The mixture is dominated by water molecules with only traces of the ions.

The equation is

H₂O + H₂O <---> H₃O¹⁺+ OH^1-

Дата добавления: 2014-12-08