JEE Main & Advanced Chemistry Some Basic Concepts of Chemistry / रसायन की कुछ मूलभूत अवधारणाएँ Question Bank Chemical stoichiometry

  • question_answer
    100 ml of 0.1 N hypo decolourised iodine by the addition of x g of crystalline copper sulphate to excess of KI. The value of ?x? is (molecular wt. of \[CuS{{O}_{4}}.5{{H}_{2}}O\]is 250)

    A)                 5.0 g      

    B)                 1.25 g

    C)                 2.5 g      

    D)                 4 g

    Correct Answer: C

    Solution :

               \[\overset{+2\,\,\,\,\,\,\,\,\,\,\,\,}{\mathop{CuS{{O}_{4}}}}\,+2KI\to {{K}_{2}}S{{O}_{4}}+\overset{+2\,\,\,\,\,}{\mathop{Cu{{I}_{2}}}}\,\];     \[2\overset{+2\,\,\,\,\,}{\mathop{Cu{{I}_{2}}}}\,\to \overset{+1\,\,\,\,\,}{\mathop{Cu{{I}_{2}}}}\,+{{I}_{2}}\]                    \[{{I}_{2}}+2N{{a}_{2}}{{S}_{2}}{{O}_{3}}\to 2NaI+N{{a}_{2}}{{S}_{4}}{{O}_{6}}\]                    Eq. wt. Of \[CuS{{O}_{4}}.5{{H}_{2}}O=\text{Mol}\text{. wt}\text{.}=\text{250}\]                    100 ml of 0.1 N hypo º 100 ml of 0.1 N \[CuS{{O}_{4}}.5{{H}_{2}}O\]                                 \[=\frac{250\times 0.1\times 100}{100}=2.5\,gm\]


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