1.

Given: The heat of sublimation of K(s) is 89 kJ mol^(-1). K(g) rarrK^(o+)(g)+e^(-), DeltaH^(Theta) = 419 kJ F_(2)(g) rarr 2F(g),DeltaH^(Theta) = 155 kJ The lattice enegry of KF(s) is -813kJ mol^(-1), the heat of formation of KF(s) is -563 kJ mol^(-1). the E_(A) of F(g) is

Answer»

`-413`
`-336`
`-1149`
`+413`

Solution :Given that:
Heat of sulmiation of `K(s)`
`K(s) rarr K(v),Delta_("sub")H^(Theta) = 89 kJ mol^(-1)`
Heat of ionisation
`K(g) rarr K^(o+) (g) +e^(-),Delta_(i)H^(Theta) = 419 kJ mol^(-1)`
Heat of atomisation of `F_(2)`
`F_(2)(g) rarr 2F(g),Delta_(a)H^(Theta) = 155 kJ mol^(-1)`
LATTICE enegry `Delta_(U)H^(Theta) =- 813 kJ mol^(-1)`
Heat of formation `Delta_(f)H^(Theta) =- 563 kJ mol^(-1)`
[Heat of electron affinify of `F(g) = ?]`
`:. Delta_(f)H = Delta_("sub")H^(Theta) +Delta_(lie)H^(Theta) +(1)/(2)Delta_(a)H^(Theta) +Delta_(E_(A))H^(Theta) +Delta_(i)H^(Theta)`
or `Delta_(E_(A))H^(Theta) = Delta_(f)H - Delta_("sub")H^(Theta) - Delta_(i)H^(Theta) - (1)/(2)Delta_(a)H^(Theta) - Delta_(i)H^(Theta)`
Substituting all the VALUES:
`Delta_(E_(A))H^(Theta) =- 563 - 89 - 419 - (155)/(2)+813.0`
`~~-336 kJ mol^(-1)`


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