The formation of O 2-( g ) starting from O ( g ) is endothermic by 603 kJ mol -1. If electron affinity of O ( g ) is -141 kJ mol -1, the second electron affinity of oxygen would be

Question

The formation of O 2-( g ) starting from O ( g ) is endothermic by 603 kJ mol -1. If electron affinity of O ( g ) is -141 kJ mol -1, the second electron affinity of oxygen would be (A) 603 kJ mol -1 (B) -603 kJ mol -1 (C) -744 kJ mol -1 (D) +744 kJ mol -1

Tardigrade Admin · Accepted Answer

O ( g )+2 e - arrow O 2-, Δ H=603 kJ mol -1 ....... (i); O ( g )+ e - arrow O -, Δ H=-141 kJ mol -1.......(ii) (i) -(ii) gives: O -( g )+ e - arrow O 2-( g ) Δ H=603-(-141)=744 kJ mol -1

Q. The formation of $O^{2 -} (g)$ starting from $O (g)$ is endothermic by $603 k J m o l^{- 1}$ . If electron affinity of $O (g)$ is $- 141 k J m o l^{- 1}$ , the second electron affinity of oxygen would be

$603 k J m o l^{- 1}$

$- 603 k J m o l^{- 1}$

$- 744 k J m o l^{- 1}$

$+ 744 k J m o l^{- 1}$

$O (g) + 2 e^{-} \to O^{2 -}, Δ H = 603 k J m o l^{- 1}$ ....... (i);
$O (g) + e^{-} \to O^{-}, Δ H = - 141 k J m o l^{- 1}$ .......(ii)
(i) -(ii) gives:
$O^{-} (g) + e^{-} \to O^{2 -} (g)$
$Δ H = 603 - (- 141) = 744 k J m o l^{- 1}$

Q. The formation of O2−(g) starting from O(g) is endothermic by 603kJmol−1. If electron affinity of O(g) is −141kJmol−1, the second electron affinity of oxygen would be

603kJmol−1

−603kJmol−1

−744kJmol−1

+744kJmol−1