JEE Main & Advanced Chemistry Equilibrium / साम्यावस्था Question Bank Mock Test - Ionic Equilibrium

  • question_answer
    The degree of dissociation of water at \[25{}^\circ C\] is \[1.9\times {{10}^{-7}}\] % and density is 1.0 g \[c{{m}^{-3}}\]. The ionic constant for water is

    A) \[1.0\times {{10}^{-10}}\]       

    B) \[1.0\times {{10}^{-14}}\]

    C) \[1.0\times {{10}^{-16}}\]       

    D) \[1.0\times {{10}^{-8}}\]

    Correct Answer: B

    Solution :

    [b] \[\underset{(1-\alpha )c}{\mathop{{{H}_{2}}O}}\,\rightleftharpoons \underset{\alpha c}{\mathop{{{H}^{+}}}}\,+\underset{\alpha c}{\mathop{O{{H}^{-}}}}\,\] \[\alpha =\frac{1.9\times {{10}^{-7}}}{100};\]Density of water =\[\frac{1.0g}{c{{m}^{2}}}\] \[\therefore c=\frac{1}{18}\times 1000=55.56moles/l\] \[\therefore [{{H}^{+}}]=55.56\times 1.9\times {{10}^{-9}}=1.055\times {{10}^{-7}}\] \[\therefore {{K}_{w}}=[{{H}^{+}}][O{{H}^{-}}]={{(1.055\times {{10}^{-7}})}^{2}}=1.0\times {{10}^{-14}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner