RAJASTHAN PMT Rajasthan - PMT Solved Paper-2005

  • question_answer
    The equivalent weight of \[KMn{{O}_{4}}\] in acidic medium is:

    A) \[158\]                                 

    B) \[52.67\]

    C) \[31.6\]                               

    D) \[49\]

    Correct Answer: C

    Solution :

    In acidic medium \[KMn{{O}_{4}}\] reacts as \[2KMn{{O}_{4}}+2{{H}_{2}}S{{O}_{4}}\xrightarrow{{}}{{K}_{2}}S{{O}_{4}}+2MnS{{O}_{4}}\]                                                                 \[+3{{H}_{2}}O+5O\] or            \[MnO_{4}^{-}\xrightarrow{{}}M{{n}^{2+}}\] Oxidation number of\[Mn+7+2\] \[\therefore \]  change in oxidation number                 \[=7-2=5\] \[\therefore \]equivalent weight of \[KMn{{O}_{2}}=\frac{formula\,\,weight\,\,of\,\,KMn{{O}_{4}}}{4}\]                 \[=\frac{158}{5}=31.6\]


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