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4. Strong and weak

The conductivity of a solution of HCl in water is large, that of a solution of acetic acid (azijnzuur), however, is much smaller.
This difference also exist voor bases: ammonia (small conductivity) and sodium hydroxide (large conductivity).

HCl(aq) H+(aq) + Cl-(aq)
The equilibrium state is positioned completely at the right side: the reaction is completed.
Virtually all HCl-molecules deliver a hydrogen ion.
The acid dissociation constant of HCl is very large.
HCl is a strong acid.
NaOH(aq) + H2O(l) Na+.H2O(aq) + OH-(aq)
The equilibrium state is positioned completely at the right side: the reaction is completed.
Virtually all NaOH-units accept a hydrogen ion from water.
The base dissociation constant of NaOH is very large.
NaOH is a strong base.
HOAc(aq) H+(aq) + OAc-(aq)
The equilibrium state is positioned at the left side.
Only a few HOAc-molecules deliver a hydrogen ion.
The acid dissociation constant of HOAc is rather small.
HOAc is a weak acid.
NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)
The equilibrium state is positioned at the left side.
Only a few NH3-molecules accept a hydrogen ion.
The base dissociation constant of NH3 is rather small.
NH3 is a weak base.


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Summary

 
Strong
Weak
Acid
Base
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