Classification of Elements and Periodicity in Properties

Classification of Elements and Periodicity in Properties

Question

The first ionisation potential of Na is 5.1 eV. The value of electron gain enthalpy of Na+ will be

  • -2.55 eV

  • -5.1 eV

  • -10.2 eV

  • +2.55 eV

Answer

B.

-5.1 eV

Na → Na+ + e- (first IE)
Na+ + e- →Na
Since reaction is reverse, so electron gain enthalpy of Na+
ΔH (eg)=-5.1 eV

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