Balancing a chemical equation is very simple. One has to only make sure that the number of elements (and charge in case of redox reactions) on both sides of the equation are the same. This is in accordance with the law of conservation of mass that the total mass of elements present in the products of a chemical reaction has to be equal to the total mass of elements present in the reactants.
Hence the number of atoms of each element remains the same before and after a chemical reaction.
a) CH4 + O2 ---------> CO2 + H2O
Reactant | Product |
C = 1 | C = 1 |
H = 4 | H = 2 |
O = 2 | O = 3 |
Reactant | Product |
Zn = 1 | Zn = 1 |
S = 1 | S = 1 |
O = 2 | O = 3 |
2 ZnS+ 3 O2---------> 2 ZnO+ 2 SO2
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