Question

The solubility $ C{{a}_{3}}{{(P{{O}_{4}})}_{2}} $ is s mole. What is the solubility product of $ C{{a}_{3}}{{(P{{O}_{4}})}_{2}} $ ?

• A. $ 8{{s}^{3}} $
• B. $ 9{{s}^{2}} $
• C. $ 108{{s}^{5}} $
• D. $ 72{{s}^{2}} $

Answer 1

Answer: (C)

$ \underset{\begin{smallmatrix} \text{s mole litr}{{\text{e}}^{-1}} \\ \text{(soluble)} \end{smallmatrix}}{\mathop{{{a}_{3}}{{(P{{O}_{4}})}_{2}}}}\,\xrightarrow{{}}\underset{\begin{smallmatrix} \text{3s mole} \\ \text{litr}{{\text{e}}^{-1}} \end{smallmatrix}}{\mathop{3C{{a}^{2+}}}}\,+\underset{\begin{smallmatrix} \text{2s mole} \\ \text{litr}{{\text{e}}^{-1}} \end{smallmatrix}}{\mathop{2P{{O}_{4}}^{3-}}}\, $ $ {{K}_{sp}} $ of $ C{{a}_{3}}{{(P{{O}_{4}})}_{2}}=3{{[C{{a}^{+\,+}}]}^{3}}+{{[P{{O}_{4}}^{3-}]}^{2}} $ $ ={{(3s)}^{3}}\times {{(2s)}^{2}} $ $ =27{{s}^{3}}\times 4{{s}^{2}}=108{{s}^{5}} $