Question

When sodium is placed in water, sodium hydroxide and hydrogen are formed. How do you write the balanced equation for this reaction?

Answer 1

The balanced equation is given when the number of atoms in the reactant is equal to the number of atoms in the product; let that it be a multi-reactant or multi-product system.
From the above statement it is clear that sodium and water react in definite proportions to form sodium hydroxide and hydrogen as the products.

Complete answer:
Let us see the reaction and try to balance it using some basic rules and properties;
We have given that the;
Sodium is placed in water i.e. sodium and water reacts in the environment to form sodium hydroxide and hydrogen. Knowing their atomic or molecular formulas we can solve the given query.
Sodium – Na
Water - ${{H}_{2}}O$
Sodium hydroxide – NaOH
Hydrogen - ${{H}_{2}}$
We know the rule of balanced equations i.e. the number of atoms in the reactant side is equal to the number of atoms in the product side. So,
The equation representing the above reaction will be,
$Sodium+Water\to Sodium-hydroxide+Hydrogen$ i.e.
$Na+{{H}_{2}}O\to NaOH+\dfrac{1}{2}{{H}_{2}}$.

Note:
Do note that the equation can be balanced as stated above but can be written in the convenient ways as,
$Na+{{H}_{2}}O\to NaOH+\dfrac{1}{2}{{H}_{2}}$ is same to the equation $2Na+2{{H}_{2}}O\to 2NaOH+{{H}_{2}}$ ; for this, we just need to multiply whole equation by 2 (which then is recognised as stoichiometric coefficient).
Also, note that while we balance the equation, we adjust the stoichiometric coefficients (as stated above) and not the suffixes involved.