## How to balance a chemical equation?

A chemical equation tells us the type of reaction between different reactants. Chemical equation gives the states of the reactants and products.  One can calculate the amount of products required for required amount of products.

To balance a chemical equation, very interesting method is algebraic expression method.

for example:  C3H8 + O2 -----> CO2  + H2O

The above reaction is to be balanced using algebraic expressions

step 1) the coefficients of Each reactants and products assumed to be a,b,c,d,...

aC3H8 + b O2 -----> c CO2  + d H2O

step 2) identify and count the number of elements on both sides of the reaction

carbon: 3a = c

hydrogen: 8a = 2d

oxygen:  2b = 2c + d

step 3) let us assume a=1, then simplify the equations for other variable values

c = 3,     2d = 8   then d = 4             if d=4 and c =3 then 2b=6 + 4 = 10, b=5

step 4) write the chemical equation using the variable values

C3H8 + 5O2 ---> 3CO2  + 4 H2O

step 5) count the number of atoms on both sides

carbon atoms  = 3
hydrogen atoms = 8
oxygen atoms = 10

step 6) we conclude that the equation is said to be balanced.

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