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Flashcards · 0620 · Topic 5

Chemical energetics flashcards

6 cards on Topic 5. Pick a subtopic or study them all.

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5.1 Exothermic and endothermic reactions

Exothermic reaction
Transfers thermal energy to the surroundings, so the temperature of the surroundings rises.
Endothermic reaction
Takes in thermal energy from the surroundings, so the temperature of the surroundings falls.
On a reaction pathway diagram, how can you tell a reaction is exothermic?
The products are at a lower energy level than the reactants.
Sign of ΔH for exothermic and endothermic reactionsExtended
Exothermic: ΔH is negative. Endothermic: ΔH is positive.
Activation energy, EₐExtended
The minimum energy that colliding particles must have to react.
Bond breaking and bond making: which is endothermic?Extended
Bond breaking is endothermic; bond making is exothermic. ΔH = energy to break bonds − energy released making bonds.