`AB,A_(2)` and `B_(2)` are diatomic molecules. If the bond enthalpies of `A_(2), AB` and `B_(2)` are in the ratio `1:1:0.5` and the enthalpy of formation of `AB` from `A_(2)` and `B_(2)` is `-100kJ mol^(-1)` , what is the bond enthalpy of `A_(2)` ?

Answer

A

Explanation

`(1)/(2)A-A+(1)/(2)B-B rarrAB" " Delta H= -100 KJ//"mole"`
`(1)/(2)xx+(1)/(2)(0.5 x)-x= -100" " rArr" "(x)/(2)+0.25x-x= -100`
`rArr - 0.25xx= - 100" " rArr" " x=400 KJ//"mole"`
Bond enthalpy `=400 kJ//mol`.