Calculate the magnitude of free energy in `KJ mol^(-1)` when `1` mole of a an ionic salt MX (s) is dissolved in water at `27^(@)C` . Given Lattice ene

Monjur Alahi

Calculate the magnitude of free energy in `KJ mol^(-1)` when `1` mole of a an ionic salt MX (s) is dissolved in water at `27^(@)C` . Given
Lattice energy of MX `= 780 KJ mol^(-1)`
Hydration energy of MX `=-775.0 KJ mol^(-1)`
Entropy change of dissolution at `27^(@)C = 40Jmol^(-1)K^(-1)`


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Salim Ahmed Kawsar

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Correct Answer - `-7 KJ "mol"^(-1)`
`DeltaH_("dissolution") = DeltaH_(("ionisation")) + DeltaH_(("Hydration")) = 780-77505 KJ mol^(-1)`
`DeltaG_("dissolution") = DeltaH_("dissolution") - TDeltaS_("dissolution") = 5000- 300 xx 40=-7000 J =-7 KJ mol^(-1)`

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