Germanous Hydroxide, Ge(OH)₂

Germanous Hydroxide, Ge(OH)₂, is formed as a yellow precipitate when alkali is added to a solution of the corresponding chloride. It is somewhat soluble in water, to which it imparts its yellow colour, and also in excess of alkali. If the hydroxide is heated with the liquid from which it has been precipitated it is reddened, and this is believed to be due to the tautomeric change:

→

the latter substance being the germanium analogue of formic acid. This idea is strengthened by the fact that germanous hydroxide is produced by the action of water on germanium chloroform:

HGeCl₃ + 2H₂0 = HGeOOH + 3HCl
HGeOOH ⇔ Ge(OH)₂.

Hantzsch has shown that the hydroxides of zinc, glucinum, lead, tin (stannous), and germanium all behave as feeble acids whose strengths increase in the order given. This has been done by measuring the electric conductivities of alkaline solutions of these hydroxides and also by determining the rate of hydrolysis of ethyl acetate by such solutions, and comparing these effects with those produced by the alkali alone. Thus an indication is given of the extent to which the metallic hydroxide is combined with the alkali to form a salt, and so of the acidic strength of this hydroxide. Thence it appears that germanous hydroxide is a slightly weaker acid than acetic acid. It is to be noted that the acidic character of these hydroxides of germanium, tin, and lead depends upon the ability of the elements to become quadrivalent, and also that the acidic strengths diminish with increase of atomic weight.