C6.0 – Energy Changes in Chemical Reactions

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1. Relate the terms exothermic and endothermic to the temperature changes observed during chemical reactions.

Exothermic reactions are reactions which give out heat energy to the surrounding. Examples are combustion(burning) and neutralisation reaction between acids and alkalies.

Endothermic reactions are reactions which absorb heat energy from the surroundings. Examples are photosynthesis and thermal decomposition (breaking down of compounds using heat).

1.  Demonstrate understanding that exothermic and endothermic changes relate to the transformation of chemical energy to heat (thermal energy), and vice versa.

In an exothermic reaction, the chemical energy of the reactants is converted to heat energy and released. Due to this  the products don’t have as much energy as the reactants.

In an endothermic reaction, the heat energy absorbed is turned into chemical energy by the reactants. Due to this the products have much more energy than the reactants.

Notes submitted by Lintha

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