Examples of chemical changes and physical changes:
Physical change: three-state change of water; Grinding gallstones into powder; Pouring molten iron into an iron pot; The stick is broken; Salt dissolves in water and becomes salt water; Hydrate into ice; Broken glass; The vase is broken; Rice is ground into powder; The water is frozen.
Chemical change: the burning of magnesium bars; Basic copper carbonate is decomposed by heating; Iron rusts in humid air: gunpowder explodes; Burn paper; Food is moldy; Iron will rust; Combustion of magnesium; Basic copper carbonate is decomposed by heating; Wood will burn.