Explain the following terms with examples:
1. Skeleton equation
2. Balanced equation
3. Thermochemical equation.
What do you mean by 'balancing a chemical equation'? On what principle the balancing of a chemical equation is based?
How are chemical equations balanced? discuss any two.
The methods generally used for balancing equations are:
1. The hit and trial method
2. Partial equation method
3. Oxidation number change method
4. Ion- electron method.
1. The hit and trial method: This method is used to balance simple equations. This method involves the following steps:
(i) Write the symbols and formulae of the reactants and products in the form of skeleton equation.
(ii) Select the element which occurs at the minimum number of places on the two sides. Make number of its atoms equal on both the sides of the equation by multiplying the formula by a suitable number.
(iii) The element which occurs at maximum number of places should be balanced last of all.
(iv) Balance the atoms of elementary gases last of all.
(v) When all the atoms are balanced, make the equation molecular by multiplying the equation by a suitable number.
2. Partial equation method: This method is used for balancing complicated equations. This method involves the following steps:
(i) Split the chemical equation into two or more stages.
(ii) Write simple equation for different stages and balance by hit and trial method. These equations are called partial equations.
(iii) All the step-wise equations (partial equations) are added to get the balanced equation.