InterviewSolution
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InterviewSolution
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At `25^(@)C`, when 1 mole of `MgSO_(4)` was dissolved in water, the heat evolved was found to be 91.2 kJ. One mole of `MgSO_(4) . 7H_(2)O` on dissolution gives a solution of the same composition accompanied by an absorption of 13.8 kJ. The enthalpy of hydration, i.e., `DeltaH_(h)` for the reaction `MgSO_(4)(s) + 7H_(2)O(l)rarrMgSO_(4) . 7H_(2)O(s)` :A. `-105 kJ//"mol"`B. `-77.4 kJ//"mol"`C. 105 kJ/molD. None of these |
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Answer» Correct Answer - A Given that `MgSO_(4)(s)+nH_(2)OrarrMgSO_(4)(nH_(2)O),` `Delta_(r )H_(1)=-91.2 " kJ"//"mol ....(i)"` `MgSO_(4).7H_(2)O(s)+(n-7)H_(2)OrarrMgSO_(4)(nH_(2)O)` `Delta_(r )H_(2)=13.8 " kJ"//"mol ....(ii)"` Equation (i) - (ii) or `DeltaH_("hyd")=Delta_(r )H_(1)-Delta_(r)H_(2)` `=-91.2 " kJ"//"mol"-13.8 " kJ"//"mol"` `=-105" kJ"//"mol"` |
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