CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2009

  • question_answer
    When 200 mL of aqueous solution of\[HCl\] (pH = 2) is mixed with 300 mL of an aqueous solution of NaOH (pH = 12), the pH of the resulting mixture is

    A) 10                                          

    B) 2.7

    C) 4.0                         

    D)        11.3

    E) 2

    Correct Answer: D

    Solution :

    Concentration of\[HCl\]solution\[=1\times {{10}^{-2}}\] \[\therefore \]Millimoles of\[HCl\]solution\[=200\times 1\times {{10}^{-2}}\] \[=2\] Similarly, millimoles of\[NaOH\]solution \[=300\times 1\times {{10}^{-2}}\] \[=3\] Concentration of the resultant solution \[=\frac{3-2}{300+200}\] \[=\frac{1}{500}=0.2\times {{10}^{-2}}\] \[\therefore \]\[[O{{H}^{-}}]=0.2\times {{10}^{-2}}\] \[pOH=-\log [O{{H}^{-}}]=-\log [2\times {{10}^{-3}}]=+2.70\] \[\therefore \]pH of the resulting mixture \[=14-2.70\]           \[=11.3\]


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