Dysocjacja kwasów, zasad i soli - Przykłady i zadania

When a substance breaks down into ions,
the resulting solution conducts electricity,
electrolytes undergo dissociation:
• strong (e.g. KOH, Ba(OH)₂, HCLO4, HI, HCL),
• weak (e.g. NH3, HF, HNO₂, H₂S, HCOOH).

Conditions of dissociation

Dissociation of weak electrolytes occurs when:

• the substance is soluble in water,
• the substance is poorly soluble in water (e.g. Ca(OH)₂).

Dissociation of weak electrolytes

The dissociation of weak acids, bases, and salts results in the release of ions due to the interaction with water molecules.

Dissociation of strong electrolytes

Strong electrolytes dissociate completely into their ions when dissolved in water.

Gradual dissociation

Some substances undergo gradual dissociation, such as the reaction of boric acid with water.

Hydrolysis

Molecules first undergo dissociation and then the resulting ions may undergo hydrolysis, resulting in the formation of H30+ or OH- ions.

Cation hydrolysis

• Occurs with a salt of a strong acid and weak base, such as FeCl3:
  Fe³+ + 3 CL -> FeCl3
  FeCl3 + H₂O -> Fe(OH)2+ + H3O+

Anion hydrolysis

• Occurs with a salt of a weak acid and strong base, such as Naclo:
  Naclo -> Li++ CLO~
  CLO- + H2O -> HCCO + OH-

Cation-anion hydrolysis

• Involves a salt of a weak acid and weak base, for example NH4F:
  NH4F -> NH4 + F~
  F- + H2O -> HF + OH-
  NH4+H2O -> NH3 + H30+

The degree of dissociation can be determined from tables, while the hydrolysis of a weak acid is determined by the relationship between its Ka and Kb values.