What is hit and trial method?

Balancing Chemical Equation

• Stoichiometric coefficients are added to the reactants and products to balance chemical equations.
• It's significant because the principles of mass conservation and constant proportions require a chemical equation to be applied.

Hit and trial method

• The least whole number coefficient is used to balance chemical equations in the hit and trial method.
• Count how many times an element appears on both sides of a reaction.
• A balanced element is one having the lowest frequency of occurrence.
• Metallic elements are matched first because they have the same frequency as two or more other elements.
• Equations containing several reactants and products cannot be balanced using this method.

Example

• When hydrogen $\left({\mathrm{H}}_2\right)$ gas reacts with oxygen $\left({\mathrm{O}}_2\right)$, water molecule $\left({\mathrm{H}}_2\mathrm{O}\right)$ is formed.
• The reaction is as follows:

${\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

• Count number of atoms: In this reaction, two hydrogen atoms and oxygen atoms are on the reactant side and two hydrogen atoms and one oxygen atom are on the product side.
• Balance the oxygen atoms: Multiply ${\mathrm{H}}_2\mathrm{O}$ by $2$ on the product side.
• Balance hydrogen atoms: Multiply ${\mathrm{H}}_2$ by $2$ on the reactant side.
• The balanced reaction by a hit and try method is as follows:

$2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$