The Chemistry of Warmth
📖 The Chemistry of Warmth
Exothermic reactions are like hand warmers — they release heat! Think "exit" — energy EXITS the reaction and enters the surroundings. That's why your hands feel warmer, the test tube gets hot, or combustion keeps you cosy. The products have LESS energy than the reactants — the difference escapes as heat!
Chemistry glossary
- What is an exothermic reaction?
- A reaction that releases/transfers energy to the surroundings
Every chemical reaction involves breaking existing bonds in the reactants and forming new bonds in the products. Breaking bonds always requires energy (it is endothermic). Forming new bonds always releases energy (it is exothermic).
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🧠 Memory Aids
EXO = EXIT = energy EXITS to surroundings = temperature goes UP
The "exo" prefix means "outside" or "exit". Energy exits the chemical system and goes into the surroundings, warming them up. Hand warmers, fires, and explosions all release heat — they all EXOT energy OUT.
ΔH sign rule: EXO = EXtra (negative) — you gain extra heat in the surroundings
Exothermic → ΔH is NEGATIVE (the system loses energy, so the change is negative)
On the energy profile: "EXothermic EXits — the products EXIT below the reactants on the diagram."
Now try it yourself
Quiz · Question 1 of 20
In an exothermic reaction, energy is transferred:
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