Question

In a reversible chemical reaction, equilibrium is said to have been established when the:
A) Concentration of reactants and products are equal
B) Opposing reaction cease
C) Speeds of opposing reactions become equal
D) Temperature of opposing reactions are equal

Answer 1

Hint: The reversible reaction is a type of reaction in which the reactant and product react together to give the reactants back. This concept can be used to find out the equilibrium meaning in the reversible chemical reaction.

Complete step by step answer:
1) First of all, we will learn about the reversible reaction. In a reversible reaction, the reactants \[A\] and $B$ can react to form $C$ and $D$ the $C$ and $D$ product formed will react to form \[A\] and $B$. The reactions of weak acids and weak bases form a reversible reaction. The general reaction of the reversible reaction is given below.
$xA + yB\overset {\operatorname{Re} versible} \leftrightarrows nC + mD$
Where $x,y,n,m$ indicate the stoichiometric coefficients of the number of reactants and products.
2) The chemical equilibrium in a reaction can be defined as a state in which both reactants and products are present at concentrations that don’t further react to change as per time. In simple words, an equilibrium position can be said to be the point in a chemical reaction where the concentrations of reactants and the products don't change.
3) In a reversible reaction, equilibrium is a state at which the rate of forwarding reaction and the rate of reverse reaction are equal. Therefore there will be no change in the concentration of products and reactants.
4) Hence, by analyzing the above data we came to and conclusion that in reversible chemical reaction equilibrium is said to be have been established when speeds of opposing reaction become equal

So, the correct answer is Option C”.

Note:
Weak acids and weak bases generally give reversible reactions. In a reversible reaction, the equilibrium state has the rate of forwarding reaction and the rate of reverse reaction equal but not zero. Once the equilibrium is obtained in a reaction, then some driving force by using a catalyst is needed to push the reaction towards the desired side to get the product.