What is the maximum pH that can be established in CA(OH)2.? KSP=5.5×10^-6

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Answer 1 · 2018-02-10T09:55:02

You gots the solubility equilibrium...

#Ca(OH)_2(s) stackrel(H_2O)rarrCa^(2+) +2HO^-#

And so when calcium hydroxide is placed in water....the solubility is governed by the equilibrium expression...

#K_"sp"=[Ca^(2+)][HO^-]^2#

And so if we represent the solubility of calcium hydroxide as #S#, then, #K_"sp"=(S)(2S)^2=4S^3#

...and #S=""^(3)sqrt((5.5xx10^-6)/4)=1.11xx10^-2*mol*L^-1#.

Now this represents the solubility of calcium hydroxide, and thus in a saturated solution, #[HO^-]=0.0222*mol*L^-1#...

#pOH=-log_10(0.0222)=1.65#...

#pH=14-pOH=12.35#...