Balancing chemical equation refers to balancing the stoichiometric coefficients on the reactants and products side. This must be done as the chemical equation obeys the law of conservation of mass and momentum.
Reaction between lead nitrate and potassium iodide
The reaction between lead nitrate and potassium iodide is an example of a precipitation reaction.
Pb(NO3)2 + 2KI + PbI2 + 2KNO3
Steps to balance chemical equation
Following are the easy steps to balance the equation:
Step 1: Write the Unbalanced Chemical Equation
Let us consider an unbalanced equation
Pb(NO3)2 + KI → PbI2 + KNO3
Step 2: Write Down Number of Atoms
Write down the number of atoms of each element present on both reactant as well as product side
| Atom | Reactant side | Product side |
| Pb | 1 | 1 |
| I | 1 | 2 |
| N | 2 | 1 |
| O | 6 | 3 |
Step 3: Add Coefficients To Balance the Mass in a Chemical Equation
Note that the coefficients that are to be added must be a whole number and one coefficient added applies to all the atoms present in that one particular molecule.
For example: (NO3)2 implies 2 hydrogen atoms and 6 oxygen atoms.
First try to balance the single element o atom and then move n to hydrogen and oxygen.
So here we will first balance lead, nitrogen and oxygen. Go by trial and error method.
Adding 2 iodine-on both sides makes iodine balanced. Then will move to nitrogen and then oxygen. On adding 2 KI and balancing with reactant side makes the equation balanced.
The same trial and error procedure is now followed to balance oxygen 3 O2 then we have 6 oxygen atoms on the reactant side and also 6 oxygen atoms on the product side.
Hence The balanced chemical equation is: Pb(NO3)2 + 2KI → PbI2 + 2KNO3
Answer
The reaction between lead nitrate and potassium iodide is
Pb(NO3)2 + 2KI → PbI2 + 2KNO3
