Physical And Chemical Change Flashcards
Physical change
No new substance are formed
Energy changes are small in relation to chemical changes
Mass, numbers of atoms and molecules are conserved
Rearrangement of molecules during physical change
Molecules separate when water evaporates to form water vapour
When ice melts molecules become disorderly arranged due to breaking of intermolecular forces
Chemical change
New chemical substances are formed
Energy changes are much larger than those of the physical change
Mass and atoms are conserved, but the number of molecules is not
Endothermic reaction
Energy is absorbed during the reaction
Exothermic reaction
Energy is released during the reaction
Examples of a chemical change
Decomposition of hydrogen peroxide to form water and oxygen
Heating of iron and sulphur
Reaction of lead nitrate and potassium iodide
