Summary Chapter 6 - Chemical Energetics CIE IGCSE Chemistry

TOPIC 6 – Chemical Energetics


· EXOTHERMIC REACTIONS:
- A reaction that transfers energy to the surroundings so the temperature of the surrounding increases.
- Examples: combustion, many oxidation reactions + neutralisation
- Day-to-day examples: hand warmers, self-heating cans for coffee or tea,…
- In these reactions energy is released when bonds are formed in products.
- Energy needed to break bonds > energy released




· ENDOTHERMIC REACTIONS:
- A reaction that takes in energy from the surroundings so the temperature of the surrounding decreases.
- Examples: thermal decomposition, reaction of citric acids
- Day-to-day examples: some sport ice packs are based on endothermic reactions.
- In these reactions energy is taken to break bonds in the reactants.
- Energy needed to break bonds < energy released.




· TO CALCULATE THE ENERGY OF THESE REACTIONS:




· BURNING FUELS:

- Hydrogen can be used as a fuel because it can be burnt to produce energy.
- Burning fuels releases heat energy.
- These reactions involve reacting fuels with oxygen / oxidation of fuels.