. At 25 °C, 1 mole of MgSO4 was dissolved in water, the heat evolved was found to be 91.2 kJ.


At 25 °C, 1 mole of MgSO4 was dissolved in water, the heat evolved was found to be 91.2 kJ.

One mole of MgSO47H2O on dissolution give a solution of the same composition accompanied by an absorption of 13.8 kJ. The enthalpy of hydration for the reaction

MgSO4 (s) + 7H2O(1) 7H2O(1) → MgSO4  7H2O(s) is

A. 115 kJ/mol

B. 105 kJ/mol

C. -105 kJ/mol

D. -77.5 kJ/mol

Best Answer

Correct Answer:

C. –105 kJ/mol

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