Question

energy diagram
what is the correct sign convention for the overall energy change based on this reaction graph?
unchanging (no δh) negative (-δh)
unknown (?δh) positive (+δh)

Explanation:

Step1: Analyze Energy Diagram

In a reaction energy diagram, the overall energy change ($\Delta H$) is determined by comparing the energy of reactants (start) and products (end). Here, the product energy is higher than reactant energy.

Step2: Relate to $\Delta H$ Sign

$\Delta H = E_{products} - E_{reactants}$. If $E_{products} > E_{reactants}$, $\Delta H$ is positive (endothermic, energy absorbed). So the sign convention is positive ($+\Delta H$).

Answer:

positive (+ΔH)