Question

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

Explanation:

Step1: Analyze Energy Diagram

In a reaction energy diagram, the overall energy change ($\Delta H$) is the difference between the energy of the products and the energy of the reactants. If the products have higher energy than the reactants, the reaction is endothermic, and $\Delta H$ is positive. If the products have lower energy, it's exothermic, and $\Delta H$ is negative.
Looking at the given diagram, the final energy (products) is higher than the initial energy (reactants).

Step2: Determine $\Delta H$ Sign

Since products have more energy than reactants, the change in enthalpy $\Delta H = E_{products} - E_{reactants}$ is positive (because $E_{products} > E_{reactants}$). So the correct sign convention is positive ($+\Delta H$).

Answer:

positive ($+\Delta H$)