Question

To which type of reaction, Le Chatelier’s principle can always be applied?
A) Reversible
B) Elementary
C) Synthesis
D) Decomposition
E) Double Replacement

Answer 1

The effect of change in conditions that is temperature, pressure, volume, and concentration on the equilibrium of the reaction is given by using Le Chatelier’s principle. The system adjusts itself in such a way that changes that take place are nullified to maintain the equilibrium in the system.

Complete solution:
Le Chatelier’s principle states that any change in temperature, pressure, concentration, or volume of the system is carried out then opposite and predictable changes are taking place in the system to achieve the new equilibrium state.
A reversible reaction is a reaction where reactant reacts to give products also product molecules react to give reactants molecules also.
The general representation of the reversible reaction is as follows:
$A\, + \,B\, \rightleftharpoons \,C + D$
In the case of the reversible reaction, if any change is carried out on the reactant side then the equilibrium is shifted to the product side then nullifies the effect of the change and vice versa. This is because the reaction is reversible. Thus, in the case of the reversible reaction, Le Chatelier’s principle is always applicable.
Thus, option A) reversible reaction is the correct answer to the question.
The elementary reaction is the reaction in which takes place in the single-step where 2 or more reactants react to give products.
$A\, + \,B\, \to \,products$
As the reaction is not reversible Le Chatelier’s principle is not always followed by such a reaction. Hence, option B) elementary reaction is incorrect.
In a synthesis reaction, different atoms or molecules react and give different product moles and the reaction is not always reversible. Therefore, Le Chatelier’s principle is not always obeyed.
$A\, + \,B\, \to \,C + D$
Hence, option C) synthesis reaction is incorrect.
In a decomposition reaction, the reactant molecule is broken down into simple molecules.
$A\,B\, \to \,A + B$
Here we can see that the decomposition reaction is not always reversible. Therefore, Le Chatelier’s principle is not always an application. Hence, option D) decomposition reaction is incorrect.
In the case of the double replacement reaction combining molecules exchange their ions and form the product molecules.
$AB\, + \,CD \to \,AD + BC$
Here, the reversible reaction may or may not be possible. Therefore, Le Chatelier’s principle is not always an application. Hence, option E) double replacement reaction is incorrect.

Thus, option A) reversible reaction is the correct answer to the question.

Note: Le Chatelier’s principle states that any system which is reversible can maintain the equilibrium by nullifying the effect of stress applied to it. It indicates that to apply Le Chatelier’s principle on any system it must be reversible.