The ⇌ symbol is your key visual reminder:
- → = one-way street (irreversible reaction)
- ⇌ = two-way road (reversible reaction, traffic flows both ways)
For the energy rule, remember the phrase: "FORWARD EXO = BACKWARD ENDO" — if energy is released going forward, it must be absorbed going backward. Think of a ball rolling down a hill (exothermic forward) — you need to push it back up the same hill (endothermic backward), using exactly the same energy it released coming down.
For copper sulfate: Blue has water, White has none — heat makes it white, add water makes it blue.
This memory aid covers Memory Aid: Double Arrow = Two-Way Traffic within Reversible Reactions for GCSE Chemistry. Revise Reversible Reactions in Rates of Reaction for GCSE Chemistry with 20 exam-style questions and 12 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. 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.
Practice questions for Reversible Reactions
What does the symbol ⇌ mean when used in a chemical equation?
Explain the relationship between the energy changes in the forward and reverse reactions of a reversible reaction.