Question

If the value of ${K_{eq}}$ is very small, it indicates that equilibrium occurs-
A.At low product concentration
B.At high product concentration
C.After considerable time
D.With the help of catalyst
E.With no forward reaction

Answer 1

Hint: We know that at equilibrium the rate of forward reaction is equal to the rate of backward reaction. So the ratio of these rates is always constant which is called equilibrium constant. The equilibrium constant is the ratio of the concentration of products to the concentration of reactants with the concentration raised to the appropriate stoichiometric coefficient. It is written as-
$ \Rightarrow $${K_{eq}}$=$\dfrac{{\left[ {{\text{Product}}} \right]}}{{\left[ {{\text{Reactant}}} \right]}}$ where $\left[ {} \right]$ is a symbol for concentration

Complete step by step answer:
It is given that the value of ${K_{eq}}$ is very small then we have to find the condition for equilibrium.
${K_{eq}}$ is equilibrium constant which is equal to the rate constant of forward reaction upon the rate constant of backward reaction. In other words it is the ratio of concentration of products to the concentration of reactants with their power raised to the given stoichiometric coefficient.
It can be written as-
$ \Rightarrow $${K_{eq}}$=$\dfrac{{\left[ {{\text{Product}}} \right]}}{{\left[ {{\text{Reactant}}} \right]}}$
Here since the value of equilibrium constant is very small then we can say that-
$ \Rightarrow \left[ {{\text{Product}}} \right] < \left[ {{\text{Reactant}}} \right]$
The concentration of reactants is higher than the concentration of products. So we can say that we achieve equilibrium at low product concentration.
Since the concentration of reactants is higher than products only few molecules of reactants are changed to product and most of the reactant molecules remain unchanged.

Hence the correct answer is option A.

Note:
If the value of equilibrium constant is very large then the concentration of product is greater than the concentration of products and all the reactants are used in the reaction to form products. The equilibrium constants tells us-
The amount of reactant present at equilibrium in the reaction.
Amount of product present at equilibrium in the reaction.