Ionic solid is dissolved in water if:
Correct answer: B. ∆Hhyd > ∆H°f
- A. ∆H°f > ∆Hhyd
- B. ∆Hhyd > ∆H°f
- C. ∆Hhyd = ∆H°f
- D. ∆Hhyd ≤ ∆H°f
Explanation
For an ionic solid to dissolve in water, it must overcome the energy barrier associated with breaking the ionic bonds in the solid and the energy gained from the formation of new bonds with water molecules. Whether ΔHhyd is greater or less than ΔH°f depends on the specific compounds involved. If ∆Hhyd is greater than ∆H°f , it means that the energy released during the solvation process is greater than the energy required to form one mole of the compound from its elements. This typically indicates that the dissolution of the ionic solid is thermodynamically favorable, as it releases more energy than it consumes, making the process exothermic.
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Thermochemistry measures energy changes in chemical reactions and distinguishes exothermic from endothermic processes. Work covers systems, surroundings and state functions, internal energy, the first law of thermodynamics, enthalpy and Hess's law, including the sign conventions used when heat enters or leaves a system.
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