Which one of the following is not correct statement about All?
Correct answer: D. ∆Hsoln is negative only
- A. ∆Hfusion is positive only
- B. ∆H aq is positive only
- C. ∆Hn is negative only
- D. ∆Hsoln is negative only
Explanation
The enthalpy of solution (∆Hsoln) can be either positive or negative. It is incorrect to state it is negative only, as dissolution can be an endothermic or exothermic process. For example, dissolving ammonium nitrate in water is endothermic (positive ∆Hsoln), while dissolving sodium hydroxide is exothermic (negative ∆Hsoln). The other options are incorrect because they correctly describe enthalpies: ∆Hfusion is positive as it requires energy to melt a solid, ∆Haq can vary, and ∆Hn can also be either positive or negative.
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About Thermochemistry and Energetics of Chemical Reactions
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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