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Physical & Chemical properties

Dissociation constant

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The anhydrous substance dissociates totally to form SiF4 and HF. For this reason, the substance contains HF to prevent dissociation and hydrolysis.  Under dilute aqueous conditions, the substance dissociates to form SiF4 and HF; the SiF4 formed from this reaction undergoing hydrolysis to form HF and Si(OH)4; HF dissociates (under aqueous conditions) for form the fluoride and hydronium ions. Soluble silicates engage in complex behaviour and will react further to form oxo and hydroxo species. Hexafluorosilicic acid is a strong acid with respect to loss of the first proton (complete dissociation) to form HSiF6- and H+.

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Additional information

The anhydrous substance dissociates totally to form SiF4 and HF. For this reason, the substance contains HF to prevent dissociation and hydrolysis. Under dilute aqueous conditions, the substance dissociates to form SiF4 and HF; the SiF4 formed from this reaction undergoing hydrolysis to form HF and Si(OH)4; HF dissociates (under aqueous conditions) for form the fluoride and hydronium ions. Soluble silicates engage in complex behaviour and will react further to form oxo and hydroxo species. Hexafluorosilicic acid is a strong acid with respect to loss of the first proton (complete dissociation) to form HSiF6- and H+.

The second dissociation is limited (Ka of between 10e-0.65 to 10e-1.83), with the formation of SiF62- and H+.