Which equation represents Enthalpy of formation of NaCI?
Correct answer: D. Na(s) + 1/2Cl2(g)➞NaCI ∆H= -411KJ/mol
- A. Na(s) + Cl2(g)➞NaCI ∆H= -787KJ/mol
- B. Na(s) + Cl2(g)➞ 2NaCI ∆H= -787KJ/mol
- C. 2Na(s) + Cl2(g)➞NaCI ∆H= -787KJ/mol
- D. Na(s) + 1/2Cl2(g)➞NaCI ∆H= -411KJ/mol
Explanation
Enthalpy change of formation states that it is the change in energy when 1 mole of a compound is formed from its element in their standard states, under standard conditions.In option D, all of the conditions in bold are fulfilled. However, the rest of the options either have some condition missing or are not properly balanced.
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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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