Two ions of identically the same composition but with different electrical charges may exhibit widely different properties.  For example, the ion MnO_{4}^{-} from permanganates yields a purple-red solution and differs in its chemical behavior from the ion MnO_{4}^{—­} from manganates, the solutions of which are green.

The chemical changes upon which the procedures of analytical chemistry depend are almost exclusively those in which the reacting substances are electrolytes, and analytical chemistry is, therefore, essentially the chemistry of the ions.  The percentage dissociation of the same electrolyte tends to increase with increasing dilution of its solution, although not in direct proportion.  The percentage dissociation of different electrolytes in solutions of equivalent concentrations (such, for example, as normal solutions) varies widely, as is indicated in the following tables, in which approximate figures are given for tenth-normal solutions at a temperature of about 18 deg.C.

Acids
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|
substance | percentage dissociation in
| 0.1 Equivalent solution
_____________________________________________|______________
_____________
|
HCl, HBr, hi, HNO_{3} | 90
|
HClO_{3}, HClO_{4}, HMnO_{4} | 90
|
H_{2}so_{4} <—­> H^{+} + HSO_{4}^{-} | 90
|
H_{2}C_{2}O_{4} <—­> H^{+} + HC_{2}O_{4}^{-} | 50
|
H_{2}so_{3} <—­> H^{+} + HSO{_}3^{-} | 20
|
H_{3}Po_{4} <—­> H^{+} + H_{2}Po_{4}^{-} | 27
|
H_{2}Po_{4}^{-} <—­> H^{+} + HPO_{4}^{—­} | 0.2
|
H_{3}AsO_{4} <—­> H^{+} + H_{2}AsO_{4}^{-} | 20
|
HF | 9
|
HC_{2}H_{3}O_{2} | 1.4
|
H_{2}Co_{3} <—­> H^{+} + HCO_{3}^{-} | 0.12
|
H_{2}S <—­> H^{+} + HS^{-} | 0.05
|
HCN | 0.01
|
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Bases
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|
substance | percentage dissociation in
| 0.1 Equivalent solution
_____________________________________________|______________
_____________
|
Koh, NaOH | 86
|
Ba(Oh)_{2} | 75
|
NH_{4}Oh | 1.4
|
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