Explanation:
Chemical reaction
When two or more substances react and form some new substance it is called as chemical reaction .
For example :
Al (s) + O₂ (g)----> Al₂O₃(s)
Chemical equation
It is the representation of chemical reaction in terms of symbols ,molecular formulas ,moles , states etc .
As we know all chemical reaction obeys law of chemical combination therefore chemical reaction need to be balanced .
Law of conservation of mass
Mass can neither be created nor be destroyed in a chemical reaction , it is always conserved .That is why reactions need to be balanced .
Let us balance
Al (s) + O₂ (g)----> Al₂O₃(s)
After balancing , it becomes :
2Al (s) + 3/2O₂ (g)----> Al₂O₃(s)
