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The first ionisation potential for Li is...

The first ionisation potential for Li is 5.41 eV and electron affinity of Cl is 3.61eV. Calculate `Delta H` in kJ/mol for the reaction.
`Li(g) + Cl(g) rarr Li^(+) + Cl^(-)`
Suppose that the resulting ions do not combine with each other. (1 eV= `1.60 xx 10^(-22)kJ`, Av. const.`=6.02 xx 10^(23)`)

A

70

B

100

C

170

D

270

Text Solution

Verified by Experts

The correct Answer is:
C
First ionization potential of Li= 5.4eV
Electron affinity of Cl= 3.61eV
We have `Delta H= I.P- E.A`
`=5.4 - 3.61 = 1.80eV= 1.80 xx 1.6 xx 10^(-22) kJ`
`Delta H= 2.86 xx 10^(-22)kJ`, for 1 mol Avogadro's number `=6.02 xx 10^(23)`
`Delta H= 2.86 xx 10^(-22) xx 6.02 xx 10^(23) = 170`kJ/mole
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