Question

103. State the type of reaction taking place. Also balance the equation.

$\mathrm{K}+{\mathrm{H}}_2\mathrm{O}\to \mathrm{KOH}+{\mathrm{H}}_2$

Answer 1

Step 1:- List the number of atoms of a different element present in the unbalanced equation

The given chemical equation is as follows:

$\mathrm{K}+{\mathrm{H}}_2\mathrm{O}\to \mathrm{KOH}+{\mathrm{H}}_2$

Element	Number of atoms in reactant	Number of atoms in product
K	1	1
O	1	1
H	2	3

Step 2:- Start balancing with the compound that contains a maximum number of atoms (reactant or product)

• In this KOH (Potassium hydroxide) and H₂O (Water) has maximum no of the atom and after that check which element has a maximum number of atoms.
• There is H₂O that has a maximum number of atoms. check if it is balanced or not.
• Start balancing with hydrogen

Atoms of Hydrogen	In reactant	In product
Initial	(2 in H2O)	(1 in KOH) and (2 in H2) = 3
Final (Balanced)	2 x (2 in H2O)= 4 hydrogen atoms	2 x (1 in KOH)+(2 in H2) =4 hydrogen atoms

Now hydrogen is balanced

Step 3:- Balance the other atoms

• Potassium is automatically balanced when K is multiplied by 2 in reactant

So, the balanced chemical equation is:

$\underset{\mathrm{potassium}}{2\mathrm{K}}+\underset{\mathrm{Water}}{2{\mathrm{H}}_2\mathrm{O}}\to \underset{\mathrm{Potassium}\mathrm{hydroxide}}{2\mathrm{KOH}}+\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2}$

Step 4:- Type of reaction reaction

Displacement reaction is the reaction in which more active element displaces a less active element from its compound. So, in the given reaction, Potassium replaced one hydrogen from water and form potassium hydroxide. Thus, the given r4eaction is a displacement reaction.

$\underset{\mathrm{potassium}}{2\mathrm{K}}+\underset{\mathrm{Water}}{2{\mathrm{H}}_2\mathrm{O}}\to \underset{\mathrm{Potassium}\mathrm{hydroxide}}{2\mathrm{KOH}}+\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2}$ (Displacement reaction)