eg 1. Food gets digested in our body
2. Rusting of iron.
eg Fe + H2O → Fe2O3+ H2
can be written as
3 Fe(s) + 4H2O(g) → Fe2O3(s) +4H2(g)
eg CaO(s) + H2O(l) → Ca(OH)2 (aq)
Calcium Water Calcium hydroxide oxide (slaked lime)
– Respiration is also exothermic reaction.
– Decomposition of vegetable matter into compost.
Double Displacement Reaction
– We can observe or recognise a chemical reaction by observing change
in state, colour, by evolution of gas or by change in temperature.
Physical state of the reactant and products are mentioned to make chemical
reaction more informative. eg: we use (g) for gas, (l) for liquid, (s) for solid
and (aq) for aqueous.
2Ba(OH)2+ NH4Cl → 2BaCl2+ NH4OH
eg. Reddish brown coating on iron.
(ii) Black coating on Silver
Antioxidants are added to foods containing fats and oil.