Two Levels, One Subtraction

An energy diagram looks like a landscape, and the tallest thing on it is the hill in the middle. Ignore the hill. ΔH is the vertical gap between exactly two points — where you started and where you ended — and the order of that subtraction is the whole topic. Watch a marker ride the curve, then watch the gap get read backwards and struck out.

8 STEPS · 6 QUICK CHECKS · ΔH = H(products) − H(reactants) · v1