JEE Main & Advanced Sample Paper JEE Main - Mock Test - 35

  • question_answer
    \[4\text{ }mol\]of a mixture of Mohr's salt and \[F{{e}_{2}}{{\left( S{{O}_{4}} \right)}_{3}}\]requires 500 ml of 1 M, \[{{K}_{2}}C{{r}_{2}}{{O}_{7}}\] for complete oxidation in acidic medium. The mole % of the Mohr's salt in the mixture is -

    A) 25   

    B)                    50    

    C) 60                    

    D)        75

    Correct Answer: D

    Solution :

    [d] \[C{{r}_{2}}O_{7}^{-2}+6F{{e}^{+2}}(n=1)(Moh{r}'s\,salt)\] \[+14{{H}^{\text{+}}}\xrightarrow{{}}2C{{r}^{+3}}+6F{{e}^{+3}}+7{{H}_{2}}O\] Equivalent of \[F{{e}^{+2}}\]= moles of Mohr's salt = equivalent of \[{{K}_{2}}C{{r}_{2}}{{O}_{7}}\] \[=500\times {{10}^{-3}}\times 6\times 1=3\] Hence mole percent of Mohr's salt \[=\frac{3}{4}\times 100=75\]

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