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What is the value of electron gain enthalpy of $Na^+$ if $IE_1$ of Na = 5.1 eV?
A
+2.55 eV
B
+10.2 eV
C
−5.1 eV
D
−10.2 eV
Detailed Solution
First ionisation of sodium: $Na(g) \rightarrow Na^+(g) + e^-$; energy absorbed = $IE_1$ = +5.1 eV
Electron gain by $Na^+$ is exactly the reverse process: $Na^+(g) + e^- \rightarrow Na(g)$
The energy change of a reverse process is equal in magnitude and opposite in sign.
Electron gain enthalpy of $Na^+$ = $-IE_1$ of Na
= −5.1 eV
Electron gain by $Na^+$ is exactly the reverse process: $Na^+(g) + e^- \rightarrow Na(g)$
The energy change of a reverse process is equal in magnitude and opposite in sign.
Electron gain enthalpy of $Na^+$ = $-IE_1$ of Na
= −5.1 eV