Energy Changes

Energy Changes
Enthalpy change is the amount of heat released or absorbed when a chemical reaction occurs.

Exothermic reaction – liberates heat energy to the surroundings which results in a general increase in the temperature of the surroundings.

Endothermic reaction – absorbs heat energy to the surroundings which results in a general decrease in the temperature of the surroundings.

Type of reactions Enthalpy Product energy level
Exothermic
ΔH= - ve because more heat is given out during bond forming than heat taken in to break them
Product is at a lower energy compared to reagent.
Bonds of products are stronger than bonds in reagent.

Endothermic
ΔH=+ ve because more heat is taken in to break bonds than heat is given out when bonds form.
Product is at a higher energy compared to reagent.
Bonds of reactants are stronger than products.


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Entry by
Json Lim
http://www.oleveltuition.com/