2023/2024/2025 IGCSE Chemistry Notes on Chemical Energetics
Syllabus Content:
Exothermic and endothermic reactions IGCSE Chemistry
Core
State that an exothermic reaction transfers
thermal energy to the surroundings leading
to an increase in the temperature of the
surroundings
State that an endothermic reaction takes in
thermal energy from the surroundings leading
to a decrease in the temperature of the
surroundings
Interpret reaction pathway diagrams showing
exothermic and endothermic reactions
Supplement
State that the transfer of thermal energy during
a reaction is called the enthalpy change, ∆H,
of the reaction. ∆H is negative for exothermic
reactions and positive for endothermic
reactions
Define activation energy, Ea, as the minimum
energy that colliding particles must have to
react
Draw and label reaction pathway diagrams for
exothermic and endothermic reactions using
information provided, to include:
(a) reactants
(b) products
(c) enthalpy change of the reaction, ∆H
(d) activation energy, Ea
State that bond breaking is an endothermic
process and bond making is an exothermic
process and explain the enthalpy change of a
reaction in terms of bond breaking and bond
making
Calculate the enthalpy change of a reaction
using bond energies
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