What is balanced chemical equation? Why should chemical equations be balanced?

Explanation

Chemical reactions obey law of conservation of mass so that total number of atoms of each elements in the reactants must be equal to the total number of atoms of each element in the products. So we should have to balance chemical equation.
Eg : `H_(2)+O_(2)rarr H_(2)O`
Step - 1 : Unbalanced equation `= H_(2)+O_(2)rarr H_(2)O`
Step - 2 : Compare no. of atoms of each element on both sides.
`|{:("Atom","No. of atoms in L.H.S","No. of atoms in R.H.S"),(H,2("in "H_(2)),2("in "H_(2)O)),(O,2("in "O_(2)),1("in "H_(2)O)):}|`
No. of O atoms balancing `-H_(2)+O_(2)rarr 2H_(2)O`
No. of H atoms balancing `-2H_(2)+O_(2)rarr 2H_(2)O`
Step - 3 : The above equation is balanced and write the coefficients in the smallest ratio. `2H_(2)+O_(2)rarr 2H_(2)O`
Step - 4 : Verify above equation for balancing of atoms each element on both sides.
Hence the equation is balanced.
`therefore 2H_(2)+O_(2)rarr 2H_(2)O`