Ca(OH)2 has a Ksp value of 6.46 x 10-6. Calculate how many moles of Ca(OH)2 will
ID: 602751 • Letter: C
Question
Ca(OH)2 has a Ksp value of 6.46 x 10-6. Calculate how many moles of Ca(OH)2 will dissolve in exactly 1.0 L of water only. If one added 0.01 M of CaCl2 to this solution, how many moles of Ca(OH)2 will now dissolve in 1.0 L of water containing this concentration of CaCl2?Explanation / Answer
We have for Ca(OH)2 the dissolution can be expressed as: Ca(OH)2----> Ca2+ + 2OH- then Ksp=[Ca2+][OH-]^2 now from the dissociation reaction [OH-]=2[Ca2+] and then the conc of Ca2+ can be calculated as: 4[Ca2+]^3= 6.46*10^(-6) and [Ca2+]= 0.011735 mol/lit. so,solubility of Ca(OH)2 is 0.0117325 mlo/lit. In the presence of 0.01(M) CaCl2 common ion effect will be dominating and the solubility will be (0.0117325-0.01)(M)=0.0017325(M)