JCECE Engineering JCECE Engineering Solved Paper-2015

  • question_answer
    The solubility product of \[A{{g}_{2}}Cr{{O}_{4}}\] is\[32\times {{10}^{-12}}\]. What is the concentration of \[CrO_{4}^{-}\] ions in that solution?

    A) \[2\times {{10}^{-4}}M\]                             

    B) \[16\times {{10}^{-4}}M\]

    C) \[8\times {{10}^{-4}}M\]                             

    D) \[8\times {{10}^{-8}}M\]

    Correct Answer: A

    Solution :

    \[\underset{S}{\mathop{A{{g}_{2}}Cu{{O}_{4}}}}\,\xrightarrow{{}}\underset{2S}{\mathop{2A{{g}^{+}}}}\,+\underset{S}{\mathop{CrO_{4}^{2-}}}\,\] \[\therefore \]  \[{{K}_{sp}}={{(2S)}^{2}}\times S=4{{S}^{3}}\] or            \[S={{\left( \frac{{{K}_{sp}}}{4} \right)}^{1/3}}={{\left( \frac{32\times {{10}^{-12}}}{4} \right)}^{1/3}}\]                 \[S=2\times {{10}^{-4}}M\]


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