Answer:
- 2NaCl → 2Na + Cl₂, ΔH = 822 kJ
Explanation:
The chemical equation for the formation of NaCl is:
- Na + (1/2) Cl₂ → NaCl , ΔH = - 411 kJ
That equation means that 1 mole of NaCl is formed by the reaction of 1 mole of Na and 1/2 mole of Cl₂, with a release of energy of 411 kJ.
The decomposition of NaCl is the inverse of the formation reaction; thus, you swift products and reactants and inverse the sign of the change in enthalpy:
- NaCl → Na + 1/2 Cl₂, ΔH = 411 kJ
Since you want the decomposition of 2 moles you multiply the equation and the ΔH by 2:
- 2NaCl → 2Na + Cl₂, ΔH = 822 kJ ← answer
