Question

A chemist has one mole of X-atoms.He finds that on absorption of 4.10 kJ, half of X-atoms transfer one electron to the other half.It all the resulting X ions are subsequently converted to `X^+` ions, an addition of 735 kJ is required.Find the electron affinity of X.

Answer 1

Correct Answer - 325
`X/2toX^(+)/2+e " " 1/2I.E.`…(i)
`e+X/2toX^(-)/2 " " 1/2 E.A. (-ve)`….(ii)
(i)+(ii)
`Xto1/2X^(+)+1/2X^(-) " " 1/2(I.E.-E.A.)=410 kJ`
I.E.-E.A.=820 kJ
Now `1/2X^(-)to1/2X^(+)+2e^(-)`….(iii) `DeltaH=735`
Now equation (ii) can be achieved by (i)+reverse (ii) and we will get
`1/2I.E.+1/2E.A.=735`
`I.E.+E.A.=1470`...(iv)
2E.A.=650
E.A.=325 kJ/mol.