QJEEM05Che0e3: JEE Main 2005 Chemistry - Class 11 JEEM05Che0e3 Solution: If the bond dissociation energies of XY, X 2 and Y 2 (all…

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If the bond dissociation energies of XY, X₂ and Y₂ (all diatomic molecules) are in the ratio of 1:1:0.5 and

Δ H_{f}

for the formation of XY is -200 kJ mole^-1. The bond dissociation energy of X₂ will be :

Accepted Answer

X_{2} + Y_{2} \to 2 X Y,

Δ H = 2 (- 200) .

Let

x

be the bond dissociation energy of

X_{2} .

Then

Δ H = - 400

= ξ_{x - x} + ξ_{y - y} - 2 ξ_{x - y}

= x + 0.5 x - 2 x

= - 0.5 x

or

x = \frac{400}{0.5} = 800 k J m o l^{- 1}

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