The value of enthalpy change for the process represented by the equation; (Na(s) ---> Na+(g) ΔH = ? ) is equal to:
Correct answer: C. ∆H°at of sodium + 1st I.E, of sodium
- A. I.E, of sodium
- B. ∆H, of sodium
- C. ∆H°at of sodium + 1st I.E, of sodium
- D. I.E, of sodium + ∆H of sodium
Explanation
The above equation shows that sodium atom in its solid state has converted to sodium atom in its gaseous state, therefore, enthalpy change of atomisation should be taken in account. Sodium atom has also converted into an ion with a +1 charge. This shows that it has been ionised and has lost one electron so we will take the first ionisation energy into consideration as well.
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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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