Exothermic reaction is a chemical reaction that releases energy. Drawing the enthalpy diagram for the reaction here is quite harder. The value of the exothermic reaction is assigned as negative so the value would be -500 kJ.
`A_(2) _(g) + X_(2) _(g) -> 2 AX _((g)) Delta H = -550 kJ`
Please consider the attached image.
X axis = reaction time
Y axis = enthalpy, Delta H
For, exothermic reaction, the reactants is written above the products. The highest point is the activated complex and the change in the energy between the reactants and the product is the Delta H = -550 kJ.