JEE Main & Advanced Chemistry Redox Reactions / रेडॉक्स अभिक्रियाएँ Question Bank Redox reaction and Method for balancing redox reaction

  • question_answer
    How many moles of \[{{K}_{2}}C{{r}_{2}}{{O}_{7}}\] can be reduced by 1 mole of \[S{{n}^{2+}}\]                      [MP PMT 2003]

    A)                 1/3        

    B)                 1/6

    C)                 2/3        

    D)                 1

    Correct Answer: A

    Solution :

           \[C{{r}_{2}}O_{7}^{2-}+14{{H}^{+}}+6{{e}^{-}}\to 2C{{r}^{3+}}+7{{H}_{2}}O\]            \[(S{{n}^{2+}}\to S{{n}^{4+}}+2{{e}^{-}})\times 3\]                    \[\overline{C{{r}_{2}}O_{7}^{2-}+14{{H}^{+}}+3S{{n}^{2+}}\to 3S{{n}^{4+}}+2C{{r}^{3+}}+7{{H}_{2}}O}\]                                 It is clear from this equation that 3 moles of \[S{{n}^{2+}}\] reduce one mole of \[C{{r}_{2}}O_{7}^{2-}\], hence 1 mol. of \[S{{n}^{2+}}\] will reduce \[\frac{1}{3}\] moles of \[C{{r}_{2}}O_{7}^{2-}\].


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