Question

How to balance this chemical equation?

Potassium metal and chlorine gas combine to form Potassium chloride.

Answer 1

Balancing chemical equation:

The given equation is; $\underset{\mathrm{Potassium}}{\mathrm{K}\left(\mathrm{s}\right)}+\underset{\mathrm{Chlorine}}{{\mathrm{Cl}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Potassium}\mathrm{chloride}}{\mathrm{KCl}\left(\mathrm{s}\right)}$

Steps to balance the equation:

Step 1: Write the unbalanced Chemical Equation

Let us consider the unbalanced equation : $\underset{\mathrm{Potassium}}{\mathrm{K}\left(\mathrm{s}\right)}+\underset{\mathrm{Chlorine}}{{\mathrm{Cl}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Potassium}\mathrm{chloride}}{\mathrm{KCl}\left(\mathrm{s}\right)}$

Step 2: Write down the 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
K	1	1
Cl	2	1

Step 3: Add coefficients to balance mass in a chemical equation

• First balance Chlorine and then Potassium by trial and error method.
• Add a stoichiometric coefficient of 2 on the product side to first balance the Chlorine atoms.
• Then for balancing the K atoms, we have to add a stoichiometric coefficient of 2 on the reactant side and it will balance the whole reaction given by; $2\mathrm{K}\left(\mathrm{s}\right)+{\mathrm{Cl}}_2\left(\mathrm{g}\right)\to 2\mathrm{KCl}\left(\mathrm{s}\right)$

Hence, by balancing the given equation by hit and trial method we will get : $2\mathrm{K}\left(\mathrm{s}\right)+{\mathrm{Cl}}_2\left(\mathrm{g}\right)\to 2\mathrm{KCl}\left(\mathrm{s}\right)$