The value of ΔH for the potential energy diagram in Image 2 is?

Question

The value of ΔH for the potential energy diagram in Image 2 is? 

1. 40 kJ
2. 25 kJ
3. 135 kJ
4. - 40 kJ
5. - 25 kJ

IMAGE 2

Answer 1

∆H is the difference between the energy of the products (15) and that of the reactants (40).

So you have 15 kJ - 40 kJ = - 25 kJ (answer #5). Since the value is negative (products have lower energy than reactants), the reaction is EXOTHERMIC.