Zusammenfassung der Ressource
exothermic +
endothermic reactions
- when a chemical reaction occurs, energy is transferred to or
from the surroundings - and there is often a temp. change
- exothermic reactions
- transfer energy to the surroundings
- usually energy is transferred as heat energy, causing the
reaction mixture and its surroundngs to be become hotter
- e.g. combustion, oxidation reactions
(rusting), neutralisation between
acids + alkalis
- endothermic reactions
- take energy in from the surroundings
- usually transferred as heat energy, causing the
reaction mixture + its surroundings to become colder
- e.g. electrolysis, the reaction between ethanoic +sodium carbonate,
the thermal decomposition of calcium carbonate in a blast furnace
- reversible reactions
- in reversible reactions, the reaction in 1 direction will be exothermic
+ the reaction in the other direction will be endothermic
- the decomposition of ammonium
chloride is a reversible reaction:
- ammonium chloride ->
ammonia + hydrogen chloride
- ammonium chloride <-
ammonia + hydrogen chloride
- ammonium chloride decomposes when it's
heated, so the forward reaction is endothermic
- energy must be transferred from
the surroundings for it to happen
- the backward reaction is endothermic
- energy is transferred into the
surroundings when it happens