This memory aid covers Memory Aids within Endothermic Reactions for GCSE Chemistry. Revise Endothermic Reactions in Energy Changes for GCSE Chemistry with 20 exam-style questions and 14 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 9 of 12 in this topic. Use it for quick recall, then test yourself straight afterwards so the memory aid becomes usable in an answer.
🧠 Memory Aids
ENDO = IN = energy goes IN from surroundings = temperature goes DOWN
The "endo" prefix means "inside" or "within". Energy enters the chemical system from the surroundings, cooling them down. Cold packs, photosynthesis, and dissolving ammonium nitrate all pull heat IN.
ΔH sign rule: ENDO = ENTERS = positive — positive energy change means energy is gained by the system
Endothermic → ΔH is POSITIVE (the system gains energy, so the change is positive)
On the energy profile: "ENDothermic ENDS higher — the products are higher up on the diagram than the reactants."
Exo vs Endo summary: "EXO = EXit (out, hot), ENDO = ENter (in, cold)"
Practice questions for Endothermic Reactions
In an endothermic reaction, energy is:
Explain why a sports cold pack becomes cold when activated.