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VIT Engineering VIT Engineering Solved Paper-2009

  • question_answer
    20 mL of 0.1 M acetic acid is mixed with 50 mL of potassium acetate. \[\underline{X}\] of acetic acid \[p\pi .d\pi \] at \[Xe{{O}_{3}}\]. Calculate concentration of potassium acetate if pH of the mixture is 4.8.

    A)  \[Xe{{O}_{4}}\]            

    B)  \[3:5\]

    C)  \[\Delta {{H}_{f}}(H)=218kJ/mol\]             

    D)  \[H-H\]

    Correct Answer: B

    Solution :

     Let the concentration of potassium acetate is x. From Hendersons equation, \[pH=p{{K}_{a}}+\log \frac{[salt]}{[acid]}\] \[4.8=-\log (1.8\times {{10}^{-5}})+\log \frac{x\times 50}{20\times 0.1M}\] \[4.8=4.74+\log 25x\] or \[\log 25x=0.06\] \[25x=1.148\] \[\therefore \] \[x=0.045M\]


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