[lpf1991]

0.5 mol Ca(OH)₂ in 0.5L DIW is treated with 0.5 mol CO₂ gas.  Closed system. pH is closest to:

The answer is supposed to be 10 (with all answers in intervals of 2 starting with 4 and ending with 12)

A given information shows the K_sp of Ca(OH)₂ being 3.0x10^-5

So the dissolution of Ca(OH)₂ would produce an OH^- concentration of X where X=sqrt(K_sp/2)

Is this correct?f

I then thought the gas bubbling would produce 0.5 mol of H₂CO₃, correct?

Would the H₂CO₃ then react with all of the OH^- to leave:

H₂CO₃ + HCO₃    H₃O⁺ + H₂CO₃ + HCO₃?

Any help is appreciated, thank you

[Borek]

I don't think Ksp of Ca(OH)₂ matters much. I would rather check Ksp for CaCO₃ to try to estimate pH of the saturated CaCO₃ solution.

[lpf1991]

Why does the K_sp of Ca(OH)₂ not matter much?  How will I find the concentration of CaCO₃ without find out to what extent Ca(OH)₂ dissociates?