|Class 7 Chemistry Physical and Chemical Changes||Chemical change|
A change leading to the production of a new substance is known as a chemical change. These changes are irreversible. Some of the chemical changes occurring in our day to day life include rusting of iron, silver jewellery getting tarnished or copper articles getting covered by green layer.
Fig. Iron chain left in moist air got rusted
Corrosion causes damage to car bodies, bridges, iron railings, ships and to all objects made of metals, specially those of iron.
Fig. Copper developing green coloured rust on exposure to moist air
Fig. Tarnished silver Vs polished silver
2Mg + O2 - --> 2MgO
On dissolving the ash in water it forms a new substance.
MgO +H2O - -> Mg(OH)2