Question

Write a balanced equation for Aluminium is warmed for $\mathrm{NaOH}$ (Caustic soda) solution.

Answer 1

Balancing of a chemical equation by hit and trial method:

1. The equation in which the number of atoms of all the molecules is equal on both sides of the equation is termed a balanced chemical equation.
2. As the mass can neither be created nor destroyed in a chemical reaction. That is, the total mass of the elements present in the products of a chemical reaction has to be equal to the total mass of the elements present in the reactants.
3. Given the reaction: Zinc and hydrochloric acid react to give zinc chloride and hydrogen gas.

Step: 1: Skeleton equation for the given reaction:

$\underset{\mathrm{Aluminium}}{\mathrm{Al}}+\underset{\mathrm{Sodium}\mathrm{hydroxide}}{\mathrm{NaOH}}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}}\stackrel{\mathrm{Warm}}{\to }\underset{\mathrm{Sodium}\mathrm{aluminate}}{{\mathrm{NaAlO}}_2}+\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2}$

Step: 2: Write the number of atoms on each element of both the sides of the reaction:

Elements	Number of atoms on the reactant side	Number of atoms on the product side
Al	1	1
Na	1	1
H	3	2
O	2	2

Step: 3: Balancing the uneven numbers of atoms on the reactants and product side:

1. Here, all atoms are balanced excluding “H”. So, we need to balance it by adding proper co-efficient.
2. This, can be achieved by multiplying 2 to “Al”, 2 to “NaOH”, 2 to “H₂O” , 2 to “NaAlO₂” and 3 to “H₂”
3. A balanced chemical equation is as follows: $\underset{\mathrm{Aluminium}}{2\mathrm{Al}}+\underset{\mathrm{Sodium}\mathrm{hydroxide}}{2\mathrm{NaOH}}+\underset{\mathrm{Water}}{2{\mathrm{H}}_2\mathrm{O}}\stackrel{\mathrm{Warm}}{\to }\underset{\mathrm{Sodium}\mathrm{aluminate}}{2{\mathrm{NaAlO}}_2}+\underset{\mathrm{Hydrogen}}{3{\mathrm{H}}_2}$
4. Now the number of atoms on both reactant product sides are equal.

Elements	Number of atoms on the reactant side	Number of atoms on the product side
Al	2	2
Na	2	2
H	6	6
O	4	4

As the number of atoms on both sides is equal thus, the equation is called a balanced equation.

Thus, the final balanced equation is : $\underset{\mathrm{Aluminium}}{2\mathrm{Al}}+\underset{\mathrm{Sodium}\mathrm{hydroxide}}{2\mathrm{NaOH}}+\underset{\mathrm{Water}}{2{\mathrm{H}}_2\mathrm{O}}\stackrel{\mathrm{Warm}}{\to }\underset{\mathrm{Sodium}\mathrm{aluminate}}{2{\mathrm{NaAlO}}_2}+\underset{\mathrm{Hydrogen}}{3{\mathrm{H}}_2}$