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+
+
–
–
ZnOH + Cl + H 2O ↔ Zn(OH) 2 + H + Cl ,
+
+
ZnOH + H 2O ↔ Zn(OH) 2 + H .

The excess of H + ions formed during the reaction causes the acidic

reaction of the medium (pH <7). The number of hydrolysis stages is equal

to the weakn the acid base acidity.

2 Hydrolysis of type III

Тhe Number of the hydrolysis stages is limited by the charge of a weak

electrolyte ion (anion) that is formed by the salt dissociation.

strong base ion
weak acid ion
2–
+
Na 2CO 3 ↔ 2Na + CO 3

The first stage

Na 2CO 3 + H 2O ↔ NaHCO 3 + NaOH,
–
–
2–
+
+
+
2Na + CO 3 + H 2O ↔ Na + HCO 3 + Na + OH ,
2–
–
–
CO 3 + H 2O ↔ HCO 3 + OH .

The second stage
NaHCO 3 + H 2O ↔ H 2CO 3 + NaOH,
–
–
+
–
+
Na + HCO 3 + H 2O ↔ H 2CO 3 + Na + OH ,
–
–
HCO 3 + H 2O ↔ H 2CO 3 + OH .
The excess of OН- ions, formed during the reaction, causes the alkaline
reaction of the medium (pH> 7).

The number of hydrolysis stages equals the weak acid basicity.

3 Hydrolysis of the type IV salts

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