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Energy Diagrams

▶︎  Watch it animatedinteractive step-through · ~3 min · optional

An energy diagram plots enthalpy against reaction progress. Reactants and products sit at different energy levels, and the difference between them is ΔH. For an exothermic reaction the products are lower (energy released); for an endothermic one they are higher (energy absorbed).

UNIT 6 TOPIC 6.2 • ENERGY DIAGRAMS DIAGRAM READER EXOTHERMIC REACTION Products are lower in enthalpy than reactants. enthalpy reaction progress reactants products ΔH < 0 ENDOTHERMIC REACTION Products are higher in enthalpy than reactants. enthalpy reaction progress reactants products ΔH > 0 H HOW TO READ ΔH ΔH = Hproducts − Hreactants The vertical difference between the two levels equals the enthalpy change of the reaction. CHECK Products higher → endothermic (ΔH > 0). Products lower → exothermic (ΔH < 0). ΔH is for the reaction as written. AP Chemistry · Unit 6 · Thermodynamics
An energy diagram plots enthalpy against reaction progress. For an exothermic reaction, products sit lower than reactants (energy released, ΔH < 0); for an endothermic one, products sit higher. The vertical drop or rise from reactants to products is ΔH.
Diagram Reader · Open the sandbox →

The misconceptions misread the diagram — mistaking the sign of ΔH, or confusing which level is reactants versus products. Read the vertical difference from reactants to products, and its direction tells you exothermic or endothermic.

The work

3 ways in · any order
Lesson
Energy Diagrams ›

An energy diagram shows ΔH as the enthalpy difference from reactants to products. The lesson reads exothermic and endothermic diagrams correctly, then closes with a ten-scenario check.

Skill check · 10 scenarios
Open lesson →
Diagnostic
10-item topic check ›

Ten items spanning the Topic 6.2 misconceptions: energy diagrams misread, the ΔH sign convention confused, and energy imagined to be used up.

Not started · 10 items · ~15 min
Start diagnostic →
Targeted Practice
Drill a single misconception ›

Pick one of the failure modes you missed and drill it on its own. The round is adaptive: two correct in a row clears the misconception and moves you to the next.

Take the diagnostic to identify your misconceptions
Diagnostic first