$2.$ Answer ALL parts.

For the following collinear reaction, which proceeds via a transition state labelled $,$

H $+$ F$2->[$H$$F$$F$]->$ HF $+$ F

the adiabatic activation potential energy $(0)$ is $19\mathrm{.}4$ kJ mol$1$ and the adiabatic energy

of reaction $1(0)$ is $367\mathrm{.}6$ kJ mol$1$

$.$ Further data for this reaction are given at the end

of the question.

$($a$)$ For the reactants, what energy contributions contribute to the difference between:

$($i$)$ the Born$-$Oppenheimer potential energy and the adiabatic potential energy

U$(0).$

$($ii$)$ U$(0)$ and H$(298).$