BRAINCAKEChemical changes
Revision notes for Chemical changes in AQA Combined Science: Trilogy (8464). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- Metal oxidesMetals react with oxygen to form metal oxides.
- The reactivity seriesWhen metals react, their atoms lose electrons and form positive ions.
- Extraction of metals and reductionUnreactive metals such as gold are found in the Earth as the metal itself.
- Oxidation and reduction in terms of electrons (HT only)Oxidation can also be described using electrons.
- Reactions of acids with metalsAcids react with some metals to produce a salt and hydrogen gas.
- Neutralisation of acids and salt productionAcids are neutralised by alkalis and by bases.
- Soluble saltsA soluble salt can be made by reacting an acid with a solid that does not dissolve in water, such as a metal, a metal oxide, a metal hydroxide or a…
- The pH scale and neutralisationAcids produce hydrogen ions, H+, when they dissolve in water.
- Strong and weak acids (HT only)A strong acid is completely ionised in aqueous solution, so every acid particle splits to release a hydrogen ion.
- The process of electrolysisA solid ionic compound cannot conduct electricity because its ions are locked in place.
- Electrolysis of molten ionic compoundsLead bromide, PbBr2, is a simple ionic compound made of lead ions, Pb2+, and bromide ions, Br-.
- Using electrolysis to extract metalsSome metals are extracted from their ores by heating with carbon, but this only works for metals less reactive than carbon.
- Electrolysis of aqueous solutionsAn aqueous solution contains water as well as the dissolved ionic compound.
- Representation of reactions at electrodes as half equations (HT only)At the cathode, positive ions gain electrons.