Question

Balance the given reaction:

Na + H₂O $\to$ NaOH + H₂

Answer 1

Na + H₂O $\to$ NaOH + H₂

• Balancing chemical equations should obey the law of conservation of mass and momentum.

Law of Conservation – Law of conservation of mass governs the balancing of a chemical equation. According to this law,

• mass can neither be created nor be destroyed in a chemical reaction
• the total mass of the elements present on the reactant side should be equal to the total mass of elements present on the product side.
• If the chemical equation is not balanced law of conservation is not applicable.

The rule for the balancing equation –

Step I – Firstly draw boxes around each formula. do not change anything inside the boxes while balancing the equation

[ Na ] + [H₂O] → [NaOH] + [H₂]

Step II — List the number of atoms of different elements present in the unbalanced equation

Atom	Number of atoms in Reactant [ LHS]	Number of atoms in Product [RHS]
Na	1	1
O	1	1
H	2	3

Step III — It is often convenient to start balancing with the compound that contains the maximum number of atoms. it may be a reactant or a product

• After balancing the equation we get the number of reactants and products as given in the table

Atom	Reactant side	Product side
Na	2	2
O	2	2
H	4	4

• Since the number of atoms is equal on both sides of the equations, the given chemical equation is balanced.

Step IV ---- to check the correctness of the balanced equation, we count atoms of each element on both sides of the equation

• Hence the balanced chemical equation is
• 2Na + 2H₂O $\to$ 2NaOH + H₂

Step V — Write symbols of the physical states of the reactant and product are mentioned along with their chemical formulae

• Hence the balanced chemical equation
• 2Na_[s]+ 2H₂O_[l] $\to$ 2NaOH_[aq] + H_2[g]