Classification of Elements and Periodicity in Properties - Result Question 17
####17. What is the value of electron gain enthalpy of $Na^{+}$if $IE_1$ of $Na=5.1 eV$ ?
(a) $-5.1 eV$
(b) $-10.2 eV$
(c) $+2.55 eV$
(d) $+10.2 eV$
[2011M]
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Solution:
(a) $IE_1$ of $Na=-$ Electron gain enthalpy of $Na^{+}$ $=-5.1 eV$.
In this question, temperature is to be defined as absolute zero. This is due to the fact that ionization energy and electron affinity are defined at absolute zero temperature.
Ionization enthalpy $=$ ionization energy $+\frac{5}{2} RT$
Electron gain enthalpy=electron affinity $-\frac{5}{2} RT$
