Home
Class 11
CHEMISTRY
At 25^(@)C, when 1 mole of MgSO(4) was d...

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/mol

D

None of these

Text Solution

Verified by Experts

The correct Answer is:
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"`
Promotional Banner

Topper's Solved these Questions

  • THERMODYNAMICS

    NARENDRA AWASTHI|Exercise Level 1 (Q.1 To Q.30)|6 Videos

  • THERMODYNAMICS

    NARENDRA AWASTHI|Exercise Level 1 (Q.31 To Q.60)|2 Videos

  • STOICHIOMETRY

    NARENDRA AWASTHI|Exercise Level 3 - Subjective Problems|20 Videos

Similar Questions

Explore conceptually related problems

At 298 K, the heat of solution of MgSO_(4) (s) is -91.21 kJ mol^(-1) and that of MgSO_(4). 7H_(2)O(s) is 13.81 kJ mol^(-1) . Calclate heat of hydration of MgSO_(4)(s) i.e., DeltaH for the reaction MgSO_(4)(s)+7H_(2)O(l) to MgSO_(4).7H_(2)O(s)

When 1 mole of anhydrous CuSO_(4) is dissolved in excess of water, -66.4 kJ heat is evolved. When one mole of CuSO_(4).5H_(2)O is dissolved in water, the heat change is +11.7 kJ. Calculate enthalpy of hydration of CuSO_(4) (anhydrous).

The enthalpy of dissolution of BaCl_(2)(s) and BaCl_(2).2H_(2)O are -20.6 and 8.8 KJ mol^(-1) respectively . Calculate enthalpy of hydration forgiven reaction: BaCl_(2)(s)+2H_(2)OtoBaCl_(2).2H_(2)O(s)

H_(2)underline(S_(2))O_(7)+H_(2)O to H_(2)SO_(4)

The integral enthalpies of solution of anhydrous CuSO_(4) (s) and hydrated CuSO_(4).5H_(2)O(s) are -70 kJ per mol and 10 kJ per mol respectively. Determine the magnitude of enthalpy of hydration of 0.1 mole anhydrous CuSO_(4) (s) as CuSO_(4)(s)+5H_(2)O(l)rarrCuSO_(4).5H_(2)O(s)