Question

What is meant by balancing a chemical reaction "by inspection"? Give a complete example of stoichiometric calculations for a balanced equation. Comment on two of your classmates' examples.

Answer 1

Balancing a chemical reaction by inspection is done by just looking at the particular chemical reaction and balancing the atoms on both sides by following methods:

(a) First find out the most important or complicated molecule in the reactant side ( left hand side) then give it a stoichiometric coefficient of 1 ( just assume that one molecule is present)

(b) Then balance the atoms which is present in the least number of compounds

(c) Then balance the remaining atoms and find out the smallest coefficients possible for the reaction.

example -

NH3 -------> N2 + H2

Two atoms of N forms from 1 atom of NH3 so multiply NH3 by 2

2 NH3 --------> N2 + H2

N atoms are balanced and there are 6 H atoms so we multiply H2 by 3

2 NH3 --------> N2 + 3H2

All atoms are balanced , therefore the reaction is said to be balanced

Another example

KClO3 ---------> KCl + O2

Both K and Cl atoms look balanced but the O atoms are coming from KClO3 so in order to balance O atoms we must multiply KClO3.

Multiply KClO3 by 2

2 KClO3 ---------> KCl + O2

Now multiply KCl by 2

2 KClO3 ---------> 2 KCl + O2

K and Cl atoms are balanced so in order to balance O atoms multiply O2 by 3

2 KClO3 -------> 2 KCl + 3 O2