Contents

States of matter

Atoms, elements and compounds

Stoichiometry

Electrochemistry

ElectrolysisBeing prepared
Electrolysis of solutions and electroplatingBeing prepared
Fuel cellsBeing prepared

Chemical energetics

Chemical reactions

Acids, bases and salts

Acids, bases and indicators
OxidesBeing prepared
Making saltsBeing prepared

The Periodic Table

Reading the tableBeing prepared
Group I: the alkali metalsBeing prepared
Group VII: the halogensBeing prepared
Transition elements and noble gasesBeing prepared

Metals

Metals and alloysBeing prepared
The reactivity seriesBeing prepared
CorrosionBeing prepared
Extracting metalsBeing prepared

Chemistry of the environment

WaterBeing prepared
FertilisersBeing prepared
Air quality and climateBeing prepared

Organic chemistry

Naming organic moleculesBeing prepared
Crude oil and alkanesBeing prepared
AlkenesBeing prepared
Alcohols and carboxylic acidsBeing prepared
PolymersBeing prepared

Experimental techniques and chemical analysis

Mixtures and separation
Measuring and planning experimentsBeing prepared
Crystallisation
Distillation
Paper chromatography
Choosing methods and checking purityBeing prepared
TitrationBeing prepared
Gas testsBeing prepared
Anion testsBeing prepared
Cation and flame testsBeing prepared

Part 2 of 2

Page 02

Calculating ΔH from bond energies

identify

Try it yourself

Supplement. Which expression gives the enthalpy change, ΔH, of a reaction?

identify: name or select.

Choose one answera.Energy given out making bonds − energy taken in breaking bondsb.Energy taken in breaking bonds + energy given out making bondsc.Energy taken in breaking bonds − energy given out, made positived.Energy taken in breaking bonds − energy given out making bonds

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Scope and sources

Cambridge IGCSE Chemistry 0620 · 2026–2028 v2 · Original learning materials.

Bond breaking and bond making (5.1 Supplement 7–8): bond breaking as endothermic and bond making as exothermic, the enthalpy change of a reaction from the energy in and the energy out, and calculating ΔH from bond energies. Exothermic and endothermic reactions, reaction pathway diagrams and activation energy are in the previous module; Hess’s law and energy cycles are not part of 0620.

Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.

Official Cambridge syllabus