Physical and chemical changes Flashcards
Physical properties
The characteristics of matter that can be seen through direct observation. Eg colour, shape, size, mass, phase of substances etc
Physical change
A change in which the chemical composition of a substance doesn’t change. No new substances are formed
Chemical properties
The characteristics of matter than can only be observed when one substance changes into a different substance.
Signs of a chemical change
- change in colour
- change in energy
- change in odour
- formation of a gas or solid
Chemical change
A change in which new substances are formed (always)
Exothermic reaction
Reactions which transform chemical potential energy into thermal energy. They release more energy than they take in
Endothermic reactions
Reactions which transform thermal energy into chemical potential energy. Endothermic reactions take in more energy than they release
Synthesis reaction
Reaction in which two or more simpler substances combine to form a compound
Decomposition
Reaction in which a compound is broken down into simpler substances
Displacement
Reaction in which an atom or group of atoms is replaced by an atom or group of atoms
Ion exchange
Reaction in which an ion from one compound is exchanged with a similarly charged ion from another compound
Precipitation reaction
Reaction in which a solid compound is formed when solutions of two soluble compounds are mixed
Acid- base / Neutralisation reaction
Reaction in which an acid reactions with a base to form a salt (ionic compound) and water
Redox reactions
Reaction in which electron transfer takes place from the reducing agent to the oxidising agent
Combustion
An exothermic reaction with oxygen
