What are the equilibrium concentrations of the dissolved ions in a saturated solution of #Fe(OH)_2# at 25°C?

1 Answer
Aug 3, 2017

Answer:

We need #K_"sp"# for #Fe(OH)_2#.........

Explanation:

And we assess the equilibrium......

#Fe(OH)_2(s)rightleftharpoonsFe^(2+) + 2HO^-#

For which this site quotes #K_"sp"=8xx10^-16#.

So we set the solubility of #Fe(OH)_2-=S#.

And thus #K_"sp"=[Fe^(2+)][HO^-]^2=Sxx(2S)^2=4S^3#

And thus......#S=""^(3)sqrt((8.0xx10^-16)/4)#

#=5.85xx10^-6*mol*L^-1#

And so #Fe^(2+)=5.85xx10^-6*mol*L^-1#

And #[HO^-]=1.17xx10^-5*mol*L^-1#

Can you work out the solubilities in #g*L^-1#?